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Informed TDD – Kata “To Roman Numerals”

- by Ralf Westphal

Originally posted on: http://geekswithblogs.net/theArchitectsNapkin/archive/2014/05/28/informed-tdd-ndash-kata-ldquoto-roman-numeralsrdquo.aspxIn a comment on my article on what I call Informed TDD (ITDD) reader gustav asked how this approach would apply to the kata “To Roman Numerals”. And whether ITDD wasn´t a violation of TDD´s principle of leaving out “advanced topics like mocks”. I like to respond with this article to his questions. There´s more to say than fits into a commentary. Mocks and TDD I don´t see in how far TDD is avoiding or opposed to mocks. TDD and mocks are orthogonal. TDD is about pocess, mocks are about structure and costs. Maybe by moving forward in tiny red+green+refactor steps less need arises for mocks. But then… if the functionality you need to implement requires “expensive” resource access you can´t avoid using mocks. Because you don´t want to constantly run all your tests against the real resource. True, in ITDD mocks seem to be in almost inflationary use. That´s not what you usually see in TDD demonstrations. However, there´s a reason for that as I tried to explain. I don´t use mocks as proxies for “expensive” resource. Rather they are stand-ins for functionality not yet implemented. They allow me to get a test green on a high level of abstraction. That way I can move forward in a top-down fashion. But if you think of mocks as “advanced” or if you don´t want to use a tool like JustMock, then you don´t need to use mocks. You just need to stand the sight of red tests for a little longer ;-) Let me show you what I mean by that by doing a kata. ITDD for “To Roman Numerals” gustav asked for the kata “To Roman Numerals”. I won´t explain the requirements again. You can find descriptions and TDD demonstrations all over the internet, like this one from Corey Haines. Now here is, how I would do this kata differently. 1. Analyse A demonstration of TDD should never skip the analysis phase. It should be made explicit. The requirements should be formalized and acceptance test cases should be compiled. “Formalization” in this case to me means describing the API of the required functionality. “[D]esign a program to work with Roman numerals” like written in this “requirement document” is not enough to start software development. Coding should only begin, if the interface between the “system under development” and its context is clear. If this interface is not readily recognizable from the requirements, it has to be developed first. Exploration of interface alternatives might be in order. It might be necessary to show several interface mock-ups to the customer – even if that´s you fellow developer. Designing the interface is a task of it´s own. It should not be mixed with implementing the required functionality behind the interface. Unfortunately, though, this happens quite often in TDD demonstrations. TDD is used to explore the API and implement it at the same time. To me that´s a violation of the Single Responsibility Principle (SRP) which not only should hold for software functional units but also for tasks or activities. In the case of this kata the API fortunately is obvious. Just one function is needed: string ToRoman(int arabic). And it lives in a class ArabicRomanConversions. Now what about acceptance test cases? There are hardly any stated in the kata descriptions. Roman numerals are explained, but no specific test cases from the point of view of a customer. So I just “invent” some acceptance test cases by picking roman numerals from a wikipedia article. They are supposed to be just “typical examples” without special meaning. Given the acceptance test cases I then try to develop an understanding of the problem domain. I´ll spare you that. The domain is trivial and is explain in almost all kata descriptions. How roman numerals are built is not difficult to understand. What´s more difficult, though, might be to find an efficient solution to convert into them automatically. 2. Solve The usual TDD demonstration skips a solution finding phase. Like the interface exploration it´s mixed in with the implementation. But I don´t think this is how it should be done. I even think this is not how it really works for the people demonstrating TDD. They´re simplifying their true software development process because they want to show a streamlined TDD process. I doubt this is helping anybody. Before you code you better have a plan what to code. This does not mean you have to do “Big Design Up-Front”. It just means: Have a clear picture of the logical solution in your head before you start to build a physical solution (code). Evidently such a solution can only be as good as your understanding of the problem. If that´s limited your solution will be limited, too. Fortunately, in the case of this kata your understanding does not need to be limited. Thus the logical solution does not need to be limited or preliminary or tentative. That does not mean you need to know every line of code in advance. It just means you know the rough structure of your implementation beforehand. Because it should mirror the process described by the logical or conceptual solution. Here´s my solution approach: The arabic “encoding” of numbers represents them as an ordered set of powers of 10. Each digit is a factor to multiply a power of ten with. The “encoding” 123 is the short form for a set like this: {1*10^2, 2*10^1, 3*10^0}. And the number is the sum of the set members. The roman “encoding” is different. There is no base (like 10 for arabic numbers), there are just digits of different value, and they have to be written in descending order. The “encoding” XVI is short for [10, 5, 1]. And the number is still the sum of the members of this list. The roman “encoding” thus is simpler than the arabic. Each “digit” can be taken at face value. No multiplication with a base required. But what about IV which looks like a contradiction to the above rule? It is not – if you accept roman “digits” not to be limited to be single characters only. Usually I, V, X, L, C, D, M are viewed as “digits”, and IV, IX etc. are viewed as nuisances preventing a simple solution. All looks different, though, once IV, IX etc. are taken as “digits”. Then MCMLIV is just a sum: M+CM+L+IV which is 1000+900+50+4. Whereas before it would have been understood as M-C+M+L-I+V – which is more difficult because here some “digits” get subtracted. Here´s the list of roman “digits” with their values: {1, I}, {4, IV}, {5, V}, {9, IX}, {10, X}, {40, XL}, {50, L}, {90, XC}, {100, C}, {400, CD}, {500, D}, {900, CM}, {1000, M} Since I take IV, IX etc. as “digits” translating an arabic number becomes trivial. I just need to find the values of the roman “digits” making up the number, e.g. 1954 is made up of 1000, 900, 50, and 4. I call those “digits” factors. If I move from the highest factor (M=1000) to the lowest (I=1) then translation is a two phase process: Find all the factors Translate the factors found Compile the roman representation Translation is just a look-up. Finding, though, needs some calculation: Find the highest remaining factor fitting in the value Remember and subtract it from the value Repeat with remaining value and remaining factors Please note: This is just an algorithm. It´s not code, even though it might be close. Being so close to code in my solution approach is due to the triviality of the problem. In more realistic examples the conceptual solution would be on a higher level of abstraction. With this solution in hand I finally can do what TDD advocates: find and prioritize test cases. As I can see from the small process description above, there are two aspects to test: Test the translation Test the compilation Test finding the factors Testing the translation primarily means to check if the map of factors and digits is comprehensive. That´s simple, even though it might be tedious. Testing the compilation is trivial. Testing factor finding, though, is a tad more complicated. I can think of several steps: First check, if an arabic number equal to a factor is processed correctly (e.g. 1000=M). Then check if an arabic number consisting of two consecutive factors (e.g. 1900=[M,CM]) is processed correctly. Then check, if a number consisting of the same factor twice is processed correctly (e.g. 2000=[M,M]). Finally check, if an arabic number consisting of non-consecutive factors (e.g. 1400=[M,CD]) is processed correctly. I feel I can start an implementation now. If something becomes more complicated than expected I can slow down and repeat this process. 3. Implement First I write a test for the acceptance test cases. It´s red because there´s no implementation even of the API. That´s in conformance with “TDD lore”, I´d say: Next I implement the API: The acceptance test now is formally correct, but still red of course. This will not change even now that I zoom in. Because my goal is not to most quickly satisfy these tests, but to implement my solution in a stepwise manner. That I do by “faking” it: I just “assume” three functions to represent the transformation process of my solution: My hypothesis is that those three functions in conjunction produce correct results on the API-level. I just have to implement them correctly. That´s what I´m trying now – one by one. I start with a simple “detail function”: Translate(). And I start with all the test cases in the obvious equivalence partition: As you can see I dare to test a private method. Yes. That´s a white box test. But as you´ll see it won´t make my tests brittle. It serves a purpose right here and now: it lets me focus on getting one aspect of my solution right. Here´s the implementation to satisfy the test: It´s as simple as possible. Right how TDD wants me to do it: KISS. Now for the second equivalence partition: translating multiple factors. (It´a pattern: if you need to do something repeatedly separate the tests for doing it once and doing it multiple times.) In this partition I just need a single test case, I guess. Stepping up from a single translation to multiple translations is no rocket science: Usually I would have implemented the final code right away. Splitting it in two steps is just for “educational purposes” here. How small your implementation steps are is a matter of your programming competency. Some “see” the final code right away before their mental eye – others need to work their way towards it. Having two tests I find more important. Now for the next low hanging fruit: compilation. It´s even simpler than translation. A single test is enough, I guess. And normally I would not even have bothered to write that one, because the implementation is so simple. I don´t need to test .NET framework functionality. But again: if it serves the educational purpose… Finally the most complicated part of the solution: finding the factors. There are several equivalence partitions. But still I decide to write just a single test, since the structure of the test data is the same for all partitions: Again, I´m faking the implementation first: I focus on just the first test case. No looping yet. Faking lets me stay on a high level of abstraction. I can write down the implementation of the solution without bothering myself with details of how to actually accomplish the feat. That´s left for a drill down with a test of the fake function: There are two main equivalence partitions, I guess: either the first factor is appropriate or some next. The implementation seems easy. Both test cases are green. (Of course this only works on the premise that there´s always a matching factor. Which is the case since the smallest factor is 1.) And the first of the equivalence partitions on the higher level also is satisfied: Great, I can move on. Now for more than a single factor: Interestingly not just one test becomes green now, but all of them. Great! You might say, then I must have done not the simplest thing possible. And I would reply: I don´t care. I did the most obvious thing. But I also find this loop very simple. Even simpler than a recursion of which I had thought briefly during the problem solving phase. And by the way: Also the acceptance tests went green: Mission accomplished. At least functionality wise. Now I´ve to tidy up things a bit. TDD calls for refactoring. Not uch refactoring is needed, because I wrote the code in top-down fashion. I faked it until I made it. I endured red tests on higher levels while lower levels weren´t perfected yet. But this way I saved myself from refactoring tediousness. At the end, though, some refactoring is required. But maybe in a different way than you would expect. That´s why I rather call it “cleanup”. First I remove duplication. There are two places where factors are defined: in Translate() and in Find_factors(). So I factor the map out into a class constant. Which leads to a small conversion in Find_factors(): And now for the big cleanup: I remove all tests of private methods. They are scaffolding tests to me. They only have temporary value. They are brittle. Only acceptance tests need to remain. However, I carry over the single “digit” tests from Translate() to the acceptance test. I find them valuable to keep, since the other acceptance tests only exercise a subset of all roman “digits”. This then is my final test class: And this is the final production code: Test coverage as reported by NCrunch is 100%: Reflexion Is this the smallest possible code base for this kata? Sure not. You´ll find more concise solutions on the internet. But LOC are of relatively little concern – as long as I can understand the code quickly. So called “elegant” code, however, often is not easy to understand. The same goes for KISS code – especially if left unrefactored, as it is often the case. That´s why I progressed from requirements to final code the way I did. I first understood and solved the problem on a conceptual level. Then I implemented it top down according to my design. I also could have implemented it bottom-up, since I knew some bottom of the solution. That´s the leaves of the functional decomposition tree. Where things became fuzzy, since the design did not cover any more details as with Find_factors(), I repeated the process in the small, so to speak: fake some top level, endure red high level tests, while first solving a simpler problem. Using scaffolding tests (to be thrown away at the end) brought two advantages: Encapsulation of the implementation details was not compromised. Naturally private methods could stay private. I did not need to make them internal or public just to be able to test them. I was able to write focused tests for small aspects of the solution. No need to test everything through the solution root, the API. The bottom line thus for me is: Informed TDD produces cleaner code in a systematic way. It conforms to core principles of programming: Single Responsibility Principle and/or Separation of Concerns. Distinct roles in development – being a researcher, being an engineer, being a craftsman – are represented as different phases. First find what, what there is. Then devise a solution. Then code the solution, manifest the solution in code. Writing tests first is a good practice. But it should not be taken dogmatic. And above all it should not be overloaded with purposes. And finally: moving from top to bottom through a design produces refactored code right away. Clean code thus almost is inevitable – and not left to a refactoring step at the end which is skipped often for different reasons. PS: Yes, I have done this kata several times. But that has only an impact on the time needed for phases 1 and 2. I won´t skip them because of that. And there are no shortcuts during implementation because of that.

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Installed SQL Server 2008 and now TFS is broken.

- by johnnycakes

Hi, My W2K3 server was running TFS 2008 SP1, SQL Server 2005 Development edition. I installed SQL Server 2008 Standard. I installed it while leaving SQL Server 2005 alone. Upgrading was not possible due to the differences in editions of the SQL Servers. Now TFS is broken. On a client computer, if I go Team - Connect to Team Foundation Server, I get this error: Team Foundation services are not available from server myserver. Technical information (for administrator): TF30059: Fatal error while initializing web service. So I head on over to my event viewer on the server. Under Application, I see one warning and two errors. First, the warning: Source: SQLSERVERAGENT Event ID: 208 Description: SQL Server Scheduled Job 'TfsWorkItemTracking Process Identities Job' (0x21F395C1F444CA499A63EBF05D717749) - Status: Failed - Invoked on: 2010-04-26 13:30:00 - Message: The job failed. The Job was invoked by Schedule 9 (ProcessIdentitiesSchedule). The last step to run was step 1 (Process Identities). Then the first error: Source: TFS Services Event ID: 3017 Description: TF53010: The following error has occurred in a Team Foundation component or extension: Date (UTC): 4/26/2010 5:36:29 PM Machine: myserver Application Domain: /LM/W3SVC/799623628/Root/Services-2-129167769888923968 Assembly: Microsoft.TeamFoundation.Server, Version=9.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a; v2.0.50727 Process Details: Process Name: w3wp Process Id: 4008 Thread Id: 224 Account name: DOMAIN\TFSService Detailed Message: TF53013: A crash report is being prepared for Microsoft. The following information is included in that report: System Values OS Version Information=Microsoft Windows NT 5.2.3790 Service Pack 2 CLR Version Information=2.0.50727.3053 Machine Name=myserver Processor Count=1 Working Set=34897920 System Directory=C:\WINDOWS\system32 Process Values ExitCode=0 Interactive=False Has Shutdown Started=False Process Environment Variables Path = C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\Program Files\Microsoft SQL Server\80\Tools\Binn\;C:\Program Files\Microsoft SQL Server\90\Tools\binn\;C:\Program Files\Microsoft SQL Server\90\DTS\Binn\;C:\Program Files\Microsoft SQL Server\90\Tools\Binn\VSShell\Common7\IDE\;C:\Program Files\Microsoft Visual Studio 8\Common7\IDE\PrivateAssemblies\;C:\Program Files\Microsoft SQL Server\100\Tools\Binn\;C:\Program Files\Microsoft SQL Server\100\DTS\Binn\;C:\Program Files\Microsoft SQL Server\100\Tools\Binn\VSShell\Common7\IDE\;C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE\PrivateAssemblies\;C:\WINDOWS\system32\WindowsPowerShell\v1.0 PATHEXT = .COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.PSC1 PROCESSOR_ARCHITECTURE = x86 SystemDrive = C: windir = C:\WINDOWS TMP = C:\WINDOWS\TEMP USERPROFILE = C:\Documents and Settings\Default User ProgramFiles = C:\Program Files FP_NO_HOST_CHECK = NO COMPUTERNAME = myserver APP_POOL_ID = Microsoft Team Foundation Server Application Pool NUMBER_OF_PROCESSORS = 1 PROCESSOR_IDENTIFIER = x86 Family 16 Model 5 Stepping 2, AuthenticAMD ClusterLog = C:\WINDOWS\Cluster\cluster.log SystemRoot = C:\WINDOWS ComSpec = C:\WINDOWS\system32\cmd.exe CommonProgramFiles = C:\Program Files\Common Files PROCESSOR_LEVEL = 16 PROCESSOR_REVISION = 0502 lib = C:\Program Files\SQLXML 4.0\bin\ ALLUSERSPROFILE = C:\Documents and Settings\All Users TEMP = C:\WINDOWS\TEMP OS = Windows_NT Request Details Url=http://myserver.domain.local:8080/Services/v1.0/Registration.asmx [method = POST] User Agent=Team Foundation (devenv.exe, 10.0.30128.1) Headers=Content-Length=390&Content-Type=text%2fxml%3b+charset%3dutf-8&Accept-Encoding=gzip%2cgzip%2cgzip&Accept-Language=en-US&Authorization=NTLM+TlRMTVNTUAADAAAAGAAYAIQAAABAAUABnAAAABAAEABYAAAADAAMAGgAAAAQABAAdAAAAAAAAADcAQAABYKIogYBsB0AAAAPN9gzQTXfZIiIFnXDlQrxjUgAWQBQAEUAUgBJAE8ATgBKAG8AaABuAG4AeQBQAEwAQQBUAFkAUABVAFMAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAUrL79KzznBHCSJi2wVjn5QEBAAAAAAAAuhQoBGflygEImxiHPrhZoAAAAAACABAASABZAFAARQBSAEkATwBOAAEACgBUAEkAVABBAE4ABAAcAEgAeQBwAGUAcgBpAG8AbgAuAGwAbwBjAGEAbAADACgAdABpAHQAYQBuAC4ASAB5AHAAZQByAGkAbwBuAC4AbABvAGMAYQBsAAUAHABIAHkAcABlAHIAaQBvAG4ALgBsAG8AYwBhAGwACAAwADAAAAAAAAAAAAAAAAAwAACg0XxPlP8uXycSFhksBJWiwp8oW7iVDqf%2f6h5U30CEXgoAEAAAAAAAAAAAAAAAAAAAAAAACQAyAEgAVABUAFAALwB0AGkAdABhAG4ALgBoAHkAcABlAHIAaQBvAG4ALgBsAG8AYwBhAGwAAAAAAAAAAAA%3d&Expect=100-continue&Host=myserver.domain.local%3a8080&User-Agent=Team+Foundation+(devenv.exe%2c+10.0.30128.1)&X-TFS-Version=1.0.0.0&X-TFS-Session=b7e7fdec-e7ee-48fc-92e8-537d1cd87ea4&SOAPAction=%22http%3a%2f%2fschemas.microsoft.com%2fTeamFoundation%2f2005%2f06%2fServices%2fRegistration%2f03%2fGetRegistrationEntries%22 Path=/Services/v1.0/Registration.asmx Local Request=False User Host Address=10.0.5.78 User=DOMAIN\Johnny [auth = NTLM] Application Provided Information Team Foundation Application Information Event Log Source = TFS Services Configured Team Foundation Server = http://myserver:8080 License Type = WorkgroupLicense Server Culture = en-US Activity Logging Name = Integration Component Name = CS Initialized = No Requests Processed = 0 Exception: TypeInitializationException Message: The type initializer for 'Microsoft.TeamFoundation.Server.IntegrationResourceComponent' threw an exception. Stack Trace: at Microsoft.TeamFoundation.Server.IntegrationResourceComponent.RegisterExceptions() at Microsoft.TeamFoundation.Server.Global.Initialize() at Microsoft.TeamFoundation.Server.TeamFoundationApplication.Init() Inner Exception Details Exception: ReflectionTypeLoadException Message: Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information. Stack Trace: at System.Reflection.Module._GetTypesInternal(StackCrawlMark& stackMark) at System.Reflection.Assembly.GetTypes() at Microsoft.TeamFoundation.Server.SqlResourceComponent.RegisterExceptions(Assembly assembly) at Microsoft.TeamFoundation.Server.IntegrationResourceComponent.RegisterExceptions() at Microsoft.TeamFoundation.Server.IntegrationResourceComponent..cctor() Application Domain Information Assembly Name=mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 Assembly CLR Version=v2.0.50727 Assembly Version=2.0.0.0 Assembly Location=C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\mscorlib.dll Assembly File Version: File: C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\mscorlib.dll InternalName: mscorlib.dll OriginalFilename: mscorlib.dll FileVersion: 2.0.50727.3053 (netfxsp.050727-3000) FileDescription: Microsoft Common Language Runtime Class Library Product: Microsoft® .NET Framework ProductVersion: 2.0.50727.3053 Debug: False Patched: False PreRelease: 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Microsoft.TeamFoundation.Server.dll FileVersion: 9.0.21022.8 FileDescription: Microsoft.TeamFoundation.Server.dll Product: Microsoft (R) Visual Studio (R) 2008 ProductVersion: 9.0.21022.8 Debug: False Patched: False PreRelease: False PrivateBuild: False SpecialBuild: False Language: Language Neutral Assembly Name=Microsoft.TeamFoundation.Common, Version=9.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a Assembly CLR Version=v2.0.50727 Assembly Version=9.0.0.0 Assembly Location=C:\WINDOWS\assembly\GAC_32\Microsoft.TeamFoundation.Common\9.0.0.0__b03f5f7f11d50a3a\Microsoft.TeamFoundation.Common.dll Assembly File Version: File: C:\WINDOWS\assembly\GAC_32\Microsoft.TeamFoundation.Common\9.0.0.0__b03f5f7f11d50a3a\Microsoft.TeamFoundation.Common.dll InternalName: Microsoft.TeamFoundation.Common.dll OriginalFilename: Microsoft.TeamFoundation.Common.dll FileVersion: 9.0.30729.1 FileDescription: Microsoft.TeamFoundation.Common.dll Product: Microsoft (R) Visual Studio (R) 2008 ProductVersion: 9.0.30729.1 Debug: False Patched: False PreRelease: False PrivateBuild: False SpecialBuild: False Language: Language Neutral Assembly Name=Microsoft.TeamFoundation, Version=9.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a Assembly CLR Version=v2.0.50727 Assembly Version=9.0.0.0 Assembly Location=C:\WINDOWS\assembly\GAC_32\Microsoft.TeamFoundation\9.0.0.0__b03f5f7f11d50a3a\Microsoft.TeamFoundation.dll Assembly File Version: File: C:\WINDOWS\assembly\GAC_32\Microsoft.TeamFoundation\9.0.0.0__b03f5f7f11d50a3a\Microsoft.TeamFoundation.dll InternalName: Microsoft.TeamFoundation.dll OriginalFilename: Microsoft.TeamFoundation.dll FileVersion: 9.0.30729.1 FileDescription: Microsoft.TeamFoundation.dll Product: Microsoft (R) Visual Studio (R) 2008 ProductVersion: 9.0.30729.1 Debug: False Patched: False PreRelease: False PrivateBuild: False SpecialBuild: False Language: Language Neutral Assembly Name=System.Security, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a Assembly CLR Version=v2.0.50727 Assembly Version=2.0.0.0 Assembly Location=C:\WINDOWS\assembly\GAC_MSIL\System.Security\2.0.0.0__b03f5f7f11d50a3a\System.Security.dll Assembly File Version: File: C:\WINDOWS\assembly\GAC_MSIL\System.Security\2.0.0.0__b03f5f7f11d50a3a\System.Security.dll InternalName: System.Security.dll OriginalFilename: System.Security.dll FileVersion: 2.0.50727.3053 (netfxsp.050727-3000) FileDescription: System.Security.dll Product: Microsoft® .NET Framework ProductVersion: 2.0.50727.3053 Debug: False Patched: False PreRelease: False PrivateBuild: False SpecialBuild: False Language: English (United States) Assembly Name=System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 Assembly CLR Version=v2.0.50727 Assembly Version=2.0.0.0 Assembly Location=C:\WINDOWS\assembly\GAC_32\System.Data\2.0.0.0__b77a5c561934e089\System.Data.dll Assembly File Version: File: C:\WINDOWS\assembly\GAC_32\System.Data\2.0.0.0__b77a5c561934e089\System.Data.dll InternalName: system.data.dll OriginalFilename: system.data.dll FileVersion: 2.0.50727.3053 (netfxsp.050727-3000) FileDescription: .NET Framework Product: Microsoft® .NET Framework ProductVersion: 2.0.50727.3053 Debug: False Patched: False PreRelease: False PrivateBuild: False SpecialBuild: False Language: English (United States) Assembly Name=Microsoft.TeamFoundation.Common.Library, Version=9.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a Assembly CLR Version=v2.0.50727 Assembly Version=9.0.0.0 Assembly Location=C:\WINDOWS\assembly\GAC_32\Microsoft.TeamFoundation.Common.Library\9.0.0.0__b03f5f7f11d50a3a\Microsoft.TeamFoundation.Common.Library.dll Assembly File Version: File: C:\WINDOWS\assembly\GAC_32\Microsoft.TeamFoundation.Common.Library\9.0.0.0__b03f5f7f11d50a3a\Microsoft.TeamFoundation.Common.Library.dll InternalName: Microsoft.TeamFoundation.Common.Library.dll OriginalFilename: Microsoft.TeamFoundation.Common.Library.dll FileVersion: 9.0.30729.1 FileDescription: Microsoft.TeamFoundation.Common.Library.dll Product: Microsoft (R) Visual Studio (R) 2008 ProductVersion: 9.0.30729.1 Debug: False Patched: False PreRelease: False PrivateBuild: False SpecialBuild: False Language: Language Neutral Assembly Name=System.Web.Mobile, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a Assembly CLR Version=v2.0.50727 Assembly Version=2.0.0.0 Assembly Location=C:\WINDOWS\assembly\GAC_MSIL\System.Web.Mobile\2.0.0.0__b03f5f7f11d50a3a\System.Web.Mobile.dll As And finally, the second error: Source: Team Foundation Error Reporting Event ID: 5000 Description: EventType teamfoundationue, P1 1.0.0.0, P2 tfs, P3 9.0.30729.1, P4 9.0.0.0, P5 general, P6 typeinitializationexcept, P7 4758b22a940fe6d9, P8 d15c14bb, P9 NIL, P10 NIL. Any ideas? Thanks.

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How does Windows 7 DNS client work?

- by Mark Allison

I am using a local DHCP and DNS server on my home network on a linux machine. It is running CentOS 6.3 with dnsmasq 2.48. It's all working fine except for local DNS lookups for Windows machines only. I have a mix of Ubuntu, CentOS and Windows machines on the network, some virtual, some physical. I have a machine called boron and the domain is called localdomain If I ping boron from any linux machine, I get [root@lithium lists]# ping -c3 boron PING boron.localdomain (10.0.0.5) 56(84) bytes of data. 64 bytes from boron.localdomain (10.0.0.5): icmp_seq=1 ttl=64 time=0.740 ms 64 bytes from boron.localdomain (10.0.0.5): icmp_seq=2 ttl=64 time=0.478 ms 64 bytes from boron.localdomain (10.0.0.5): icmp_seq=3 ttl=64 time=0.458 ms --- boron.localdomain ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 2000ms rtt min/avg/max/mdev = 0.458/0.558/0.740/0.131 ms If I do it from my Windows 7 machine, I get: Ping request could not find host boron. Please check the name and try again. If I try ping boron.localdomain I get: Pinging boron.localdomain [67.215.65.132] with 32 bytes of data: Reply from 67.215.65.132: bytes=32 time=16ms TTL=57 Reply from 67.215.65.132: bytes=32 time=188ms TTL=57 Reply from 67.215.65.132: bytes=32 time=15ms TTL=57 Reply from 67.215.65.132: bytes=32 time=14ms TTL=57 Ping statistics for 67.215.65.132: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 14ms, Maximum = 188ms, Average = 58ms which is clearly wrong. Why is it going out to the internet? Why can't my windows machine resolve the boron hostname to a FQDN? My Windows machines and linux machines get their network config from DHCP. UPDATE If I do ipconfig /all in Windows, it looks as I would expect: Windows IP Configuration Host Name . . . . . . . . . . . . : lanthanum Primary Dns Suffix . . . . . . . : Node Type . . . . . . . . . . . . : Hybrid IP Routing Enabled. . . . . . . . : No WINS Proxy Enabled. . . . . . . . : No DNS Suffix Search List. . . . . . : .localdomain Ethernet adapter Local Area Connection: Connection-specific DNS Suffix . : .localdomain Description . . . . . . . . . . . : Realtek PCIe GBE Family Controller Physical Address. . . . . . . . . : 50-E5-49-38-FC-A2 DHCP Enabled. . . . . . . . . . . : Yes Autoconfiguration Enabled . . . . : Yes IPv4 Address. . . . . . . . . . . : 10.0.0.57(Preferred) Subnet Mask . . . . . . . . . . . : 255.255.255.0 Lease Obtained. . . . . . . . . . : 23 August 2012 13:58:45 Lease Expires . . . . . . . . . . : 24 August 2012 07:58:48 Default Gateway . . . . . . . . . : 10.0.0.6 DHCP Server . . . . . . . . . . . : 10.0.0.6 DNS Servers . . . . . . . . . . . : 10.0.0.6 208.67.222.222 208.67.220.220 NetBIOS over Tcpip. . . . . . . . : Enabled When I do an nslookup I get: Server: carbon.localdomain Address: 10.0.0.6 *** carbon.localdomain can't find boron: Unspecified error However if I do ifconfig -a in Linux I get: [root@nitrogen ~]# ifconfig -a eth0 Link encap:Ethernet HWaddr 00:0C:29:AF:EC:2A inet addr:10.0.0.7 Bcast:10.0.0.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:187687 errors:0 dropped:0 overruns:0 frame:0 TX packets:5857 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:23910700 (22.8 MiB) TX bytes:712964 (696.2 KiB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:329894 errors:0 dropped:0 overruns:0 frame:0 TX packets:329894 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:67153143 (64.0 MiB) TX bytes:67153143 (64.0 MiB) and nslookup: [root@nitrogen ~]# nslookup boron Server: 10.0.0.6 Address: 10.0.0.6#53 Name: boron Address: 10.0.0.5 Both machines are on the same network using the same DHCP server. UPDATE 2 I thought the issue was resolved but I am getting intermittent DNS resolving issues but only on my Windows 7 machine. All my linux boxes are fine. This is what happens when I ping and nslookup from Windows to a Windows 2008 Server: C:\Users\mark>nslookup magnesium Server: carbon.localdomain Address: 10.0.0.6 Name: magnesium.localdomain Address: 10.0.0.12 C:\Users\mark>ping magnesium Pinging magnesium.localdomain [67.215.65.132] with 32 bytes of data: Reply from 67.215.65.132: bytes=32 time=267ms TTL=57 Reply from 67.215.65.132: bytes=32 time=162ms TTL=57 Reply from 67.215.65.132: bytes=32 time=510ms TTL=57 Reply from 67.215.65.132: bytes=32 time=146ms TTL=57 Ping statistics for 67.215.65.132: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 146ms, Maximum = 510ms, Average = 271ms And from Linux: [root@beryllium ~]# ping -c4 magnesium PING magnesium.localdomain (10.0.0.12) 56(84) bytes of data. 64 bytes from magnesium.localdomain (10.0.0.12): icmp_seq=1 ttl=128 time=0.176 ms 64 bytes from magnesium.localdomain (10.0.0.12): icmp_seq=2 ttl=128 time=0.634 ms 64 bytes from magnesium.localdomain (10.0.0.12): icmp_seq=3 ttl=128 time=0.685 ms 64 bytes from magnesium.localdomain (10.0.0.12): icmp_seq=4 ttl=128 time=0.263 ms --- magnesium.localdomain ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 3002ms rtt min/avg/max/mdev = 0.176/0.439/0.685/0.223 ms [root@beryllium ~]# nslookup magnesium Server: 10.0.0.6 Address: 10.0.0.6#53 Name: magnesium.localdomain Address: 10.0.0.12 UPDATE 3 I stopped the Windows DNS client on my Windows 7 machine with net stop dnscache and it is now working fine. It would be nice to get DNS working with the DNS client on, but I might be OK without it, what do you think?

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Memory leak involving jQuery Ajax requests

- by Eli Courtwright

I have a webpage that's leaking memory in both IE8 and Firefox; the memory usage displayed in the Windows Process Explorer just keeps growing over time. The following page requests the "unplanned.json" url, which is a static file that never changes (though I do set my Cache-control HTTP header to no-cache to make sure that the Ajax request always goes through). When it gets the results, it clears out an HTML table, loops over the json array it got back from the server, and dynamically adds a row to an HTML table for each entry in the array. Then it waits 2 seconds and repeats this process. Here's the entire webpage: <html> <head> <title>Test Page</title> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3/jquery.min.js"></script> </head> <body> <script type="text/javascript"> function kickoff() { $.getJSON("unplanned.json", resetTable); } function resetTable(rows) { $("#content tbody").empty(); for(var i=0; i<rows.length; i++) { $("<tr>" + "<td>" + rows[i].mpe_name + "</td>" + "<td>" + rows[i].bin + "</td>" + "<td>" + rows[i].request_time + "</td>" + "<td>" + rows[i].filtered_delta + "</td>" + "<td>" + rows[i].failed_delta + "</td>" + "</tr>").appendTo("#content tbody"); } setTimeout(kickoff, 2000); } $(kickoff); </script> <table id="content" border="1" style="width:100% ; text-align:center"> <thead><tr> <th>MPE</th> <th>Bin</th> <th>When</th> <th>Filtered</th> <th>Failed</th> </tr></thead> <tbody></tbody> </table> </body> </html> If it helps, here's an example of the json I'm sending back (it's this exact array wuith thousands of entries instead of just one): [ { mpe_name: "DBOSS-995", request_time: "09/18/2009 11:51:06", bin: 4, filtered_delta: 1, failed_delta: 1 } ] EDIT: I've accepted Toran's extremely helpful answer, but I feel I should post some additional code, since his removefromdom jQuery plugin has some limitations: It only removes individual elements. So you can't give it a query like `$("#content tbody tr")` and expect it to remove all of the elements you've specified. Any element that you remove with it must have an `id` attribute. So if I want to remove my `tbody`, then I must assign an `id` to my `tbody` tag or else it will give an error. It removes the element itself and all of its descendants, so if you simply want to empty that element then you'll have to re-create it afterwards (or modify the plugin to empty instead of remove). So here's my page above modified to use Toran's plugin. For the sake of simplicity I didn't apply any of the general performance advice offered by Peter. Here's the page which now no longer memory leaks: <html> <head> <title>Test Page</title> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3/jquery.min.js"></script> </head> <body> <script type="text/javascript">  </script> <div id="message" style="color:red"></div> <table id="content" border="1" style="width:100% ; text-align:center"> <thead><tr> <th>MPE</th> <th>Bin</th> <th>When</th> <th>Filtered</th> <th>Failed</th> </tr></thead> <tbody id="id_field_required"></tbody> </table> </body> </html> FURTHER EDIT: I'll leave my question unchanged, though it's worth noting that this memory leak has nothing to do with Ajax. In fact, the following code would memory leak just the same and be just as easily solved with Toran's removefromdom jQuery plugin: function resetTable() { $("#content tbody").empty(); for(var i=0; i<1000; i++) { $("#content tbody").append("<tr><td>" + "DBOSS-095" + "</td>" + "<td>" + 4 + "</td>" + "<td>" + "09/18/2009 11:51:06" + "</td>" + "<td>" + 1 + "</td>" + "<td>" + 1 + "</td></tr>"); } setTimeout(resetTable, 2000); } $(resetTable);

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Exception with RubyAMF and Ruby 1.9 although code works

- by Tam

I'm getting an exception with RubyAMF using Ruby 1.9 and Rails 2.3.5. Although code afterward executes normally I'm not very comfortable with seeing such exception in the log file. Do you know what is causing it: >>>>>>>> RubyAMF >>>>>>>>> #<RubyAMF::Actions::PrepareAction:0x0000010139ff48> took: 0.00020 secs >>>>>>>> RubyAMF >>>>>>>>> #<RubyAMF::Actions::RailsInvokeAction:0x0000010139ff10> took: 0.29973 secs You have a nil object when you didn't expect it! You might have expected an instance of Array. The error occurred while evaluating nil.include? /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/activerecord-2.3.5/lib/active_record/attribute_methods.rb:142:in `create_time_zone_conversion_attribute?' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/activerecord-2.3.5/lib/active_record/attribute_methods.rb:75:in `block in define_attribute_methods' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/activerecord-2.3.5/lib/active_record/attribute_methods.rb:71:in `each' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/activerecord-2.3.5/lib/active_record/attribute_methods.rb:71:in `define_attribute_methods' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/activerecord-2.3.5/lib/active_record/attribute_methods.rb:242:in `method_missing' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/activerecord-2.3.5/lib/active_record/base.rb:2832:in `hash' /Users/tammam56/lal/vendor/plugins/ruby_amf/io/amf_serializer.rb:366:in `hash' /Users/tammam56/lal/vendor/plugins/ruby_amf/io/amf_serializer.rb:366:in `hash' /Users/tammam56/lal/vendor/plugins/ruby_amf/io/amf_serializer.rb:366:in `[]=' /Users/tammam56/lal/vendor/plugins/ruby_amf/io/amf_serializer.rb:366:in `store_object' /Users/tammam56/lal/vendor/plugins/ruby_amf/io/amf_serializer.rb:234:in `write_amf3_object' /Users/tammam56/lal/vendor/plugins/ruby_amf/io/amf_serializer.rb:154:in `write_amf3' /Users/tammam56/lal/vendor/plugins/ruby_amf/io/amf_serializer.rb:78:in `write' /Users/tammam56/lal/vendor/plugins/ruby_amf/io/amf_serializer.rb:70:in `block in run' /Users/tammam56/lal/vendor/plugins/ruby_amf/io/amf_serializer.rb:56:in `upto' /Users/tammam56/lal/vendor/plugins/ruby_amf/io/amf_serializer.rb:56:in `run' /Users/tammam56/lal/vendor/plugins/ruby_amf/app/filters.rb:91:in `block in run' /Users/tammam56/.rvm/rubies/ruby-1.9.1-p378/lib/ruby/1.9.1/benchmark.rb:309:in `realtime' /Users/tammam56/lal/vendor/plugins/ruby_amf/app/filters.rb:91:in `run' /Users/tammam56/lal/vendor/plugins/ruby_amf/app/filters.rb:12:in `block in run' /Users/tammam56/lal/vendor/plugins/ruby_amf/app/filters.rb:11:in `each' /Users/tammam56/lal/vendor/plugins/ruby_amf/app/filters.rb:11:in `run' /Users/tammam56/lal/vendor/plugins/ruby_amf/app/rails_gateway.rb:28:in `service' /Users/tammam56/lal/app/controllers/rubyamf_controller.rb:19:in `gateway' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/base.rb:1331:in `perform_action' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/filters.rb:617:in `call_filters' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/filters.rb:610:in `perform_action_with_filters' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/benchmarking.rb:68:in `block in perform_action_with_benchmark' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/activesupport-2.3.5/lib/active_support/core_ext/benchmark.rb:17:in `block in ms' /Users/tammam56/.rvm/rubies/ruby-1.9.1-p378/lib/ruby/1.9.1/benchmark.rb:309:in `realtime' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/activesupport-2.3.5/lib/active_support/core_ext/benchmark.rb:17:in `ms' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/benchmarking.rb:68:in `perform_action_with_benchmark' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/rescue.rb:160:in `perform_action_with_rescue' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/flash.rb:146:in `perform_action_with_flash' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/base.rb:532:in `process' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/filters.rb:606:in `process_with_filters' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/base.rb:391:in `process' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/base.rb:386:in `call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/routing/route_set.rb:437:in `call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/dispatcher.rb:87:in `dispatch' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/dispatcher.rb:121:in `_call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/dispatcher.rb:130:in `block in build_middleware_stack' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/activerecord-2.3.5/lib/active_record/query_cache.rb:29:in `call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/activerecord-2.3.5/lib/active_record/query_cache.rb:29:in `block in call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/query_cache.rb:34:in `cache' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/activerecord-2.3.5/lib/active_record/query_cache.rb:9:in `cache' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/activerecord-2.3.5/lib/active_record/query_cache.rb:28:in `call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/connection_pool.rb:361:in `call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/string_coercion.rb:25:in `call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/rack-1.0.1/lib/rack/head.rb:9:in `call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/rack-1.0.1/lib/rack/methodoverride.rb:24:in `call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/params_parser.rb:15:in `call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/session/cookie_store.rb:93:in `call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/failsafe.rb:26:in `call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/rack-1.0.1/lib/rack/lock.rb:11:in `block in call' <internal:prelude>:8:in `synchronize' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/rack-1.0.1/lib/rack/lock.rb:11:in `call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/dispatcher.rb:114:in `block in call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/reloader.rb:34:in `run' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/actionpack-2.3.5/lib/action_controller/dispatcher.rb:108:in `call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/rails-2.3.5/lib/rails/rack/static.rb:31:in `call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/rack-1.0.1/lib/rack/urlmap.rb:46:in `block in call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/rack-1.0.1/lib/rack/urlmap.rb:40:in `each' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/rack-1.0.1/lib/rack/urlmap.rb:40:in `call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/rails-2.3.5/lib/rails/rack/log_tailer.rb:17:in `call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/rack-1.0.1/lib/rack/content_length.rb:13:in `call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/rack-1.0.1/lib/rack/chunked.rb:15:in `call' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/rack-1.0.1/lib/rack/handler/mongrel.rb:64:in `process' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/mongrel-1.1.5/lib/mongrel.rb:159:in `block in process_client' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/mongrel-1.1.5/lib/mongrel.rb:158:in `each' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/mongrel-1.1.5/lib/mongrel.rb:158:in `process_client' /Users/tammam56/.rvm/gems/ruby-1.9.1-p378/gems/mongrel-1.1.5/lib/mongrel.rb:285:in `block (2 levels) in run '

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Silverlight 4 + WCF RIA - Data Service Design Best Practices

- by Chadd Nervig

Hey all. I realize this is a rather long question, but I'd really appreciate any help from anyone experienced with RIA services. Thanks! I'm working on a Silverlight 4 app that views data from the server. I'm relatively inexperienced with RIA Services, so have been working through the tasks of getting the data I need down to the client, but every new piece I add to the puzzle seems to be more and more problematic. I feel like I'm missing some basic concepts here, and it seems like I'm just 'hacking' pieces on, in time-consuming ways, each one breaking the previous ones as I try to add them. I'd love to get the feedback of developers experienced with RIA services, to figure out the intended way to do what I'm trying to do. Let me lay out what I'm trying to do: First, the data. The source of this data is a variety of sources, primarily created by a shared library which reads data from our database, and exposes it as POCOs (Plain Old CLR Objects). I'm creating my own POCOs to represent the different types of data I need to pass between server and client. DataA - This app is for viewing a certain type of data, lets call DataA, in near-realtime. Every 3 minutes, the client should pull data down from the server, of all the new DataA since the last time it requested data. DataB - Users can view the DataA objects in the app, and may select one of them from the list, which displays additional details about that DataA. I'm bringing these extra details down from the server as DataB. DataC - One of the things that DataB contains is a history of a couple important values over time. I'm calling each data point of this history a DataC object, and each DataB object contains many DataCs. The Data Model - On the server side, I have a single DomainService: [EnableClientAccess] public class MyDomainService : DomainService { public IEnumerable<DataA> GetDataA(DateTime? startDate) { /*Pieces together the DataAs that have been created since startDate, and returns them*/ } public DataB GetDataB(int dataAID) { /*Looks up the extended info for that dataAID, constructs a new DataB with that DataA's data, plus the extended info (with multiple DataCs in a List<DataC> property on the DataB), and returns it*/ } //Not exactly sure why these are here, but I think it //wouldn't compile without them for some reason? The data //is entirely read-only, so I don't need to update. public void UpdateDataA(DataA dataA) { throw new NotSupportedException(); } public void UpdateDataB(DataB dataB) { throw new NotSupportedException(); } } The classes for DataA/B/C look like this: [KnownType(typeof(DataB))] public partial class DataA { [Key] [DataMember] public int DataAID { get; set; } [DataMember] public decimal MyDecimalA { get; set; } [DataMember] public string MyStringA { get; set; } [DataMember] public DataTime MyDateTimeA { get; set; } } public partial class DataB : DataA { [Key] [DataMember] public int DataAID { get; set; } [DataMember] public decimal MyDecimalB { get; set; } [DataMember] public string MyStringB { get; set; } [Include] //I don't know which of these, if any, I need? [Composition] [Association("DataAToC","DataAID","DataAID")] public List<DataC> DataCs { get; set; } } public partial class DataC { [Key] [DataMember] public int DataAID { get; set; } [Key] [DataMember] public DateTime Timestamp { get; set; } [DataMember] public decimal MyHistoricDecimal { get; set; } } I guess a big question I have here is... Should I be using Entities instead of POCOs? Are my classes constructed correctly to be able to pass the data down correctly? Should I be using Invoke methods instead of Query (Get) methods on the DomainService? On the client side, I'm having a number of issues. Surprisingly, one of my biggest ones has been threading. I didn't expect there to be so many threading issues with MyDomainContext. What I've learned is that you only seem to be able to create MyDomainContextObjects on the UI thread, all of the queries you can make are done asynchronously only, and that if you try to fake doing it synchronously by blocking the calling thread until the LoadOperation finishes, you have to do so on a background thread, since it uses the UI thread to make the query. So here's what I've got so far. The app should display a stream of the DataA objects, spreading each 3min chunk of them over the next 3min (so they end up displayed 3min after the occurred, looking like a continuous stream, but only have to be downloaded in 3min bursts). To do this, the main form initializes, creates a private MyDomainContext, and starts up a background worker, which continuously loops in a while(true). On each loop, it checks if it has any DataAs left over to display. If so, it displays that Data, and Thread.Sleep()s until the next DataA is scheduled to be displayed. If it's out of data, it queries for more, using the following methods: public DataA[] GetDataAs(DateTime? startDate) { _loadOperationGetDataACompletion = new AutoResetEvent(false); LoadOperation<DataA> loadOperationGetDataA = null; loadOperationGetDataA = _context.Load(_context.GetDataAQuery(startDate), System.ServiceModel.DomainServices.Client.LoadBehavior.RefreshCurrent, false); loadOperationGetDataA.Completed += new EventHandler(loadOperationGetDataA_Completed); _loadOperationGetDataACompletion.WaitOne(); List<DataA> dataAs = new List<DataA>(); foreach (var dataA in loadOperationGetDataA.Entities) dataAs.Add(dataA); return dataAs.ToArray(); } private static AutoResetEvent _loadOperationGetDataACompletion; private static void loadOperationGetDataA_Completed(object sender, EventArgs e) { _loadOperationGetDataACompletion.Set(); } Seems kind of clunky trying to force it into being synchronous, but since this already is on a background thread, I think this is OK? So far, everything actually works, as much of a hack as it seems like it may be. It's important to note that if I try to run that code on the UI thread, it locks, because it waits on the WaitOne() forever, locking the thread, so it can't make the Load request to the server. So once the data is displayed, users can click on one as it goes by to fill a details pane with the full DataB data about that object. To do that, I have the the details pane user control subscribing to a selection event I have setup, which gets fired when the selection changes (on the UI thread). I use a similar technique there, to get the DataB object: void SelectionService_SelectedDataAChanged(object sender, EventArgs e) { DataA dataA = /*Get the selected DataA*/; MyDomainContext context = new MyDomainContext(); var loadOperationGetDataB = context.Load(context.GetDataBQuery(dataA.DataAID), System.ServiceModel.DomainServices.Client.LoadBehavior.RefreshCurrent, false); loadOperationGetDataB.Completed += new EventHandler(loadOperationGetDataB_Completed); } private void loadOperationGetDataB_Completed(object sender, EventArgs e) { this.DataContext = ((LoadOperation<DataB>)sender).Entities.SingleOrDefault(); } Again, it seems kinda hacky, but it works... except on the DataB that it loads, the DataCs list is empty. I've tried all kinds of things there, and I don't see what I'm doing wrong to allow the DataCs to come down with the DataB. I'm about ready to make a 3rd query for the DataCs, but that's screaming even more hackiness to me. It really feels like I'm fighting against the grain here, like I'm doing this in an entirely unintended way. If anyone could offer any assistance, and point out what I'm doing wrong here, I'd very much appreciate it! Thanks!

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Need help with workflow in Alfresco

- by Scott Gartner

Hello SO community, I haven't had any luck getting help in the Alfresco forums, and I'm hoping for more here. We are building an application based on Alfresco and jBPM and I have defined a workflow, but I have either defined it wrong or am missing something or there are bugs in Alfresco integration with jBPM and I need help figuring out which and fixing it. Here is the problem: I have an advanced workflow and I am trying to launch it from JavaScript. Here is the code I'm using to start the workflow: var nodeId = args.nodeid; var document = search.findNode("workspace://SpacesStore/" + nodeId); var workflowAction = actions.create("start-workflow"); workflowAction.parameters.workflowName = "jbpm$nmwf:MyWorkflow"; workflowAction.parameters["bpm:workflowDescription"] = "Please edit: " + document.name; workflowAction.parameters["bpm:assignees"] = [people.getPerson("admin"), people.getPerson("andyg")]; var futureDate = new Date(); futureDate.setDate(futureDate.getDate() + 7); workflowAction.parameters["bpm:workflowDueDate"] = futureDate; workflowAction.execute(document); This runs fine and e-mail sent from the start node's default transition fires just fine. However, when I go looking for the workflow in my task list it is not there, but it is in my completed task list. The default transition (the only transition) from the start node points at a task node which has four transitions. There are 8 tasks and 22 transitions in the workflow. When I use the workflow console to start the workflow and end the start task, it properly follows the default start node transition to the next task. The new task shows up in "show tasks" but does not show up in "show my tasks" (apparently because the task was marked completed for some reason, though it is not in the "end" node). The task is: task id: jbpm$111 , name: nmwf:submitInEditing , properties: 18 If I do "show transitions" it looks just as I would expect: path: jbpm$62-@ , node: In Editing , active: true task id: jbpm$111 , name: nmwf:submitInEditing, title: submitInEditing title , desc: submitInEditing description , properties: 18 transition id: Submit for Approval , title: Submit for Approval transition id: Request Copyediting Review , title: Request Copyediting Review transition id: Request Legal Review , title: Request Legal Review transition id: Request Review , title: Request Review I don't want to post the entire workflow as it's large, but here are the first two nodes: First the swimlanes: <swimlane name="initiator"></swimlane> <swimlane name="Content Providers"> <assignment actor-id="Content Providers"> <actor>#{bpm_assignees}</actor> </assignment> </swimlane> Now the nodes: <start-state name="start"> <task name="nmwf:submitTask" swimlane="initiator"/> <transition name="" to="In Editing"> <action> <runas>admin</runas> <script> /* Code to send e-mail that a new workflow was started. I get this e-mail. */ </script> </action> </transition> </start-state> <task-node name="In Editing"> <task name="nmwf:submitInEditing" swimlane="Content Providers" />  <transition to="In Approval" name="Submit for Approval"></transition> <transition to="In Copyediting" name="Request Copyediting Review"></transition> <transition to="In Legal Review" name="Request Legal Review"></transition> <transition to="In Review" name="Request Review"></transition> </task-node> Here is the model for these two nodes: <type name="nmwf:submitTask"> <parent>bpm:startTask</parent> <mandatory-aspects> <aspect>bpm:assignees</aspect> </mandatory-aspects> </type> <type name="nmwf:submitInEditing"> <parent>bpm:workflowTask</parent> <mandatory-aspects> <aspect>bpm:assignees</aspect> </mandatory-aspects> </type> Here is a pseudo-log of running the workflow in the workflow console: :: deploy alfresco/extension/workflow/processdefinition.xml deployed definition id: jbpm$69 , name: jbpm$nmwf:MyWorkflow , title: nmwf:MyWorkflow , version: 28 :: var bpm:assignees* person admin,andyg set var {http://www.alfresco.org/model/bpm/1.0}assignees = [workspace://SpacesStore/73cf1b28-21aa-40ca-9dde-1cff492d0268, workspace://SpacesStore/03297e91-0b89-4db6-b764-5ada2d167424] :: var bpm:package package 1 set var {http://www.alfresco.org/model/bpm/1.0}package = workspace://SpacesStore/6e2bbbbd-b728-4403-be37-dfce55a83641 :: start bpm:assignees bpm:package started workflow id: jbpm$63 , def: nmwf:MyWorkflow path: jbpm$63-@ , node: start , active: true task id: jbpm$112 , name: nmwf:submitTask, title: submitTask title , desc: submitTask description , properties: 16 transition id: [default] , title: Task Done :: show transitions path: jbpm$63-@ , node: start , active: true task id: jbpm$112 , name: nmwf:submitTask, title: submitTask title , desc: submitTask description , properties: 17 transition id: [default] , title: Task Done :: end task jbpm$112 signal sent - path id: jbpm$63-@ path: jbpm$63-@ , node: In Editing , active: true task id: jbpm$113 , name: nmwf:submitInEditing, title: submitInEditing title , desc: submitInEditing description , properties: 17 transition id: Submit for Approval , title: Submit for Approval transition id: Request Copyediting Review , title: Request Copyediting Review transition id: Request Legal Review , title: Request Legal Review transition id: Request Review , title: Request Review :: show tasks task id: jbpm$113 , name: nmwf:submitInEditing , properties: 18 :: show my tasks admin: [there is no output here] I have been making the assumption that the bpm:assignees that I am setting before starting the workflow initially are getting passed to the first task node "In Editing". Clearly the assignees are on the task object and not on the workflow object. I added the assignees aspect to the start-state task so that it could hold them (after I had a problem; initially they were not there) and possibly they are still sitting there, but the start-state has ended before I even get control back from the web script (not that it would help if it wasn't ended, I need it to be in "In Editing" as the start-state is only used to log that the workflow was started). It has always confused me that the properties that I need to set on each task need to be requested before the task is entered (when you choose a transition you must provide the data for the next task before you can actually move to the next task as you have to validate that you have all of the required data first and then signal the transition). However, the code to start the workflow is asynchronous and therefore does not return either the started workflow or the current task (which in my case would be "In Editing"). So, either way you cannot set variables such as bpm:assignees and bpm:dueDate. I wonder if this is the problem with the user task list. I'm setting the assignees in the property list, but maybe those assignees are going to the start-state task and are not getting passed to the "In Editing" task? Note that this is my first jBPM workflow, so please don't assume I know what I'm doing. If you see something that looks off, it probably is and I just don't know it. Thanks in advance for any advice or help,

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Implementing an async "read all currently available data from stream" operation

- by Jon

I recently provided an answer to this question: C# - Realtime console output redirection. As often happens, explaining stuff (here "stuff" was how I tackled a similar problem) leads you to greater understanding and/or, as is the case here, "oops" moments. I realized that my solution, as implemented, has a bug. The bug has little practical importance, but it has an extremely large importance to me as a developer: I can't rest easy knowing that my code has the potential to blow up. Squashing the bug is the purpose of this question. I apologize for the long intro, so let's get dirty. I wanted to build a class that allows me to receive input from a console's standard output Stream. Console output streams are of type FileStream; the implementation can cast to that, if needed. There is also an associated StreamReader already present to leverage. There is only one thing I need to implement in this class to achieve my desired functionality: an async "read all the data available this moment" operation. Reading to the end of the stream is not viable because the stream will not end unless the process closes the console output handle, and it will not do that because it is interactive and expecting input before continuing. I will be using that hypothetical async operation to implement event-based notification, which will be more convenient for my callers. The public interface of the class is this: public class ConsoleAutomator { public event EventHandler<ConsoleOutputReadEventArgs> StandardOutputRead; public void StartSendingEvents(); public void StopSendingEvents(); } StartSendingEvents and StopSendingEvents do what they advertise; for the purposes of this discussion, we can assume that events are always being sent without loss of generality. The class uses these two fields internally: protected readonly StringBuilder inputAccumulator = new StringBuilder(); protected readonly byte[] buffer = new byte[256]; The functionality of the class is implemented in the methods below. To get the ball rolling: public void StartSendingEvents(); { this.stopAutomation = false; this.BeginReadAsync(); } To read data out of the Stream without blocking, and also without requiring a carriage return char, BeginRead is called: protected void BeginReadAsync() { if (!this.stopAutomation) { this.StandardOutput.BaseStream.BeginRead( this.buffer, 0, this.buffer.Length, this.ReadHappened, null); } } The challenging part: BeginRead requires using a buffer. This means that when reading from the stream, it is possible that the bytes available to read ("incoming chunk") are larger than the buffer. Remember that the goal here is to read all of the chunk and call event subscribers exactly once for each chunk. To this end, if the buffer is full after EndRead, we don't send its contents to subscribers immediately but instead append them to a StringBuilder. The contents of the StringBuilder are only sent back whenever there is no more to read from the stream. private void ReadHappened(IAsyncResult asyncResult) { var bytesRead = this.StandardOutput.BaseStream.EndRead(asyncResult); if (bytesRead == 0) { this.OnAutomationStopped(); return; } var input = this.StandardOutput.CurrentEncoding.GetString( this.buffer, 0, bytesRead); this.inputAccumulator.Append(input); if (bytesRead < this.buffer.Length) { this.OnInputRead(); // only send back if we 're sure we got it all } this.BeginReadAsync(); // continue "looping" with BeginRead } After any read which is not enough to fill the buffer (in which case we know that there was no more data to be read during the last read operation), all accumulated data is sent to the subscribers: private void OnInputRead() { var handler = this.StandardOutputRead; if (handler == null) { return; } handler(this, new ConsoleOutputReadEventArgs(this.inputAccumulator.ToString())); this.inputAccumulator.Clear(); } (I know that as long as there are no subscribers the data gets accumulated forever. This is a deliberate decision). The good This scheme works almost perfectly: Async functionality without spawning any threads Very convenient to the calling code (just subscribe to an event) Never more than one event for each time data is available to be read Is almost agnostic to the buffer size The bad That last almost is a very big one. Consider what happens when there is an incoming chunk with length exactly equal to the size of the buffer. The chunk will be read and buffered, but the event will not be triggered. This will be followed up by a BeginRead that expects to find more data belonging to the current chunk in order to send it back all in one piece, but... there will be no more data in the stream. In fact, as long as data is put into the stream in chunks with length exactly equal to the buffer size, the data will be buffered and the event will never be triggered. This scenario may be highly unlikely to occur in practice, especially since we can pick any number for the buffer size, but the problem is there. Solution? Unfortunately, after checking the available methods on FileStream and StreamReader, I can't find anything which lets me peek into the stream while also allowing async methods to be used on it. One "solution" would be to have a thread wait on a ManualResetEvent after the "buffer filled" condition is detected. If the event is not signaled (by the async callback) in a small amount of time, then more data from the stream will not be forthcoming and the data accumulated so far should be sent to subscribers. However, this introduces the need for another thread, requires thread synchronization, and is plain inelegant. Specifying a timeout for BeginRead would also suffice (call back into my code every now and then so I can check if there's data to be sent back; most of the time there will not be anything to do, so I expect the performance hit to be negligible). But it looks like timeouts are not supported in FileStream. Since I imagine that async calls with timeouts are an option in bare Win32, another approach might be to PInvoke the hell out of the problem. But this is also undesirable as it will introduce complexity and simply be a pain to code. Is there an elegant way to get around the problem? Thanks for being patient enough to read all of this. Update: I definitely did not communicate the scenario well in my initial writeup. I have since revised the writeup quite a bit, but to be extra sure: The question is about how to implement an async "read all the data available this moment" operation. My apologies to the people who took the time to read and answer without me making my intent clear enough.

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Storage model for various user setting and attributes in database?

- by dvd

I'm currently trying to upgrade a user management system for one web application. This web application is used to provide remote access to various networking equipment for educational purposes. All equipment is assigned to various pods, which users can book for periods of time. The current system is very simple - just 2 user types: administrators and students. All their security and other attributes are mostly hardcoded. I want to change this to something like the following model: user <-- (1..n)profile <--- (1..n) attributes. I.e. user can be assigned several profiles and each profile can have multiple attributes. At runtime all profiles and attributes are merged into single active profile. Some examples of attributes i'm planning to implement: EXPIRATION_DATE - single value, value type: date, specifies when user account will expire; ACCESS_POD - single value, value type: ref to object of Pod class, specifies which pod the user is allowed to book, user profile can have multiple such attributes with different values; TIME_QUOTA - single value, value type: integer, specifies maximum length of time for which student can reserve equipment. CREDIT_CHARGING - multi valued, specifies how much credits will be assigned to user over period of time. (Reservation of devices will cost credits, which will regenerate over time); Security permissions and user preferences can end up as profile or user attributes too: i.e CAN_CREATE_USERS, CAN_POST_NEWS, CAN_EDIT_DEVICES, FONT_SIZE, etc.. This way i could have, for example: students of course A will have profiles STUDENT (with basic attributes) and PROFILE A (wich grants acces to pod A). Students of course B will have profiles: STUDENT, PROFILE B(wich grants to pod B and have increased time quotas). I'm using Spring and Hibernate frameworks for this application and MySQL for database. For this web application i would like to stay within boundaries of these tools. The problem is, that i can't figure out how to best represent all these attributes in database. I also want to create some kind of unified way of retrieveing these attributes and their values. Here is the model i've come up with. Base classes. public abstract class Attribute{ private Long id; Attribute() {} abstract public String getName(); public Long getId() {return id; } void setId(Long id) {this.id = id;} } public abstract class SimpleAttribute extends Attribute{ public abstract Serializable getValue(); abstract void setValue(Serializable s); @Override public boolean equals(Object obj) { ... } @Override public int hashCode() { ... } } Simple attributes can have only one value of any type (including object and enum). Here are more specific attributes: public abstract class IntAttribute extends SimpleAttribute { private Integer value; public Integer getValue() { return value; } void setValue(Integer value) { this.value = value;} void setValue(Serializable s) { setValue((Integer)s); } } public class MaxOrdersAttribute extends IntAttribute { public String getName() { return "Maximum outstanding orders"; } } public final class CreditRateAttribute extends IntAttribute { public String getName() { return "Credit Regeneration Rate"; } } All attributes stored stored using Hibenate variant "table per class hierarchy". Mapping: <class name="ru.mirea.rea.model.abac.Attribute" table="ATTRIBUTES" abstract="true" > <id name="id" column="id"> <generator class="increment" /> </id> <discriminator column="attributeType" type="string"/> <subclass name="ru.mirea.rea.model.abac.SimpleAttribute" abstract="true"> <subclass name="ru.mirea.rea.model.abac.IntAttribute" abstract="true" > <property name="value" column="intVal" type="integer"/> <subclass name="ru.mirea.rea.model.abac.CreditRateAttribute" discriminator-value="CreditRate" /> <subclass name="ru.mirea.rea.model.abac.MaxOrdersAttribute" discriminator-value="MaxOrders" /> </subclass> <subclass name="ru.mirea.rea.model.abac.DateAttribute" abstract="true" > <property name="value" column="dateVal" type="timestamp"/> <subclass name="ru.mirea.rea.model.abac.ExpirationDateAttribute" discriminator-value="ExpirationDate" /> </subclass> <subclass name="ru.mirea.rea.model.abac.PodAttribute" abstract="true" > <many-to-one name="value" column="podVal" class="ru.mirea.rea.model.pods.Pod"/> <subclass name="ru.mirea.rea.model.abac.PodAccessAttribute" discriminator-value="PodAccess" lazy="false"/> </subclass> <subclass name="ru.mirea.rea.model.abac.SecurityPermissionAttribute" discriminator-value="SecurityPermission" lazy="false"> <property name="value" column="spVal" type="ru.mirea.rea.db.hibernate.customTypes.SecurityPermissionType"/> </subclass> </subclass> </class> SecurityPermissionAttribute uses enumeration of various permissions as it's value. Several types of attributes imlement GrantedAuthority interface and can be used with Spring Security for authentication and authorization. Attributes can be created like this: public final class AttributeManager { public <T extends SimpleAttribute> T createSimpleAttribute(Class<T> c, Serializable value) { Session session = HibernateUtil.getCurrentSession(); T att = null; ... att = c.newInstance(); att.setValue(value); session.save(att); session.flush(); ... return att; } public <T extends SimpleAttribute> List<T> findSimpleAttributes(Class<T> c) { List<T> result = new ArrayList<T>(); Session session = HibernateUtil.getCurrentSession(); List<T> temp = session.createCriteria(c).list(); result.addAll(temp); return result; } } And retrieved through User Profiles to which they are assigned. I do not expect that there would be very large amount of rows in the ATTRIBUTES table, but are there any serious drawbacks of such design?

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Wikipedia API: list=alllinks confusion

- by Chris Salij

I'm doing a research project for the summer and I've got to use get some data from Wikipedia, store it and then do some analysis on it. I'm using the Wikipedia API to gather the data and I've got that down pretty well. What my questions is in regards to the links-alllinks option in the API doc here After reading the description, both there and in the API itself (it's down and bit and I can't link directly to the section), I think I understand what it's supposed to return. However when I ran a query it gave me back something I didn't expect. Here's the query I ran: http://en.wikipedia.org/w/api.php?action=query&prop=revisions&titles=google&rvprop=ids|timestamp|user|comment|content&rvlimit=1&list=alllinks&alunique&allimit=40&format=xml Which in essence says: Get the last revision of the Google page, include the id, timestamp, user, comment and content of each revision, and return it in XML format. The allinks (I thought) should give me back a list of wikipedia pages which point to the google page (In this case the first 40 unique ones). I'm not sure what the policy is on swears, but this is the result I got back exactly: <?xml version="1.0"?> <api> <query><normalized> <n from="google" to="Google" /> </normalized> <pages> <page pageid="1092923" ns="0" title="Google"> <revisions> <rev revid="366826294" parentid="366673948" user="Citation bot" timestamp="2010-06-08T17:18:31Z" comment="Citations: [161]Tweaked: url. [[User:Mono|Mono]]" xml:space="preserve">  </rev> </revisions> </page> </pages> <alllinks> <l ns="0" title="!" /> <l ns="0" title="!!" /> <l ns="0" title="!!!" /> <l ns="0" title="!!!!" /> <l ns="0" title="!!!!!!!!!!!!!!!!!!!!!" /> <l ns="0" title="!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!" /> <l ns="0" title="!!!!!!!!!!!!!!!!!!!!*was up all u hater just stopingby to show u some love*!!!!!!!!!!!!!!!!!!!!!!!!!!!" /> <l ns="0" title="!!!!!!!!!!!!&&&&&&&&&&&********(( )))))F/W///CHRYSLER/FUCKING/FUCKING/FUCKING/I HATE THE QUEEN!!!/I AM HORRID HENRY/Chrysler Cirrus/php" /> <l ns="0" title="!!!!!Hephaestos IS A FUCKING WHINY GUY!!!!!!" /> <l ns="0" title="!!!!Do you really want to see this article on your default search?" /> <l ns="0" title="!!!!Legal!!!!" /> <l ns="0" title="!!!!YOU ARE A COCKSUCKING WHINY GREASER!!!!" /> <l ns="0" title="!!!BESQUERKAN!!!" /> <l ns="0" title="!!!Fuck You!!!" /> <l ns="0" title="!!!Fuck You!!! And Then Some" /> <l ns="0" title="!!!Fuck You!!! And Then some" /> <l ns="0" title="!!!Fuck You!!! And then Some" /> <l ns="0" title="!!!Fuck You!!! and Then Some" /> <l ns="0" title="!!!Three !!! Amigos!!!" /> <l ns="0" title="!!! (album)" /> <l ns="0" title="!!! (band)" /> <l ns="0" title="!!1" /> <l ns="0" title="!!BOSS!!" /> <l ns="0" title="!!Destroy-Oh-Boy!!" /> <l ns="0" title="!!Fuck you!!" /> <l ns="0" title="!!M" /> <l ns="0" title="!!Que Corra La Voz!!" /> <l ns="0" title="!! (chess)" /> <l ns="0" title="!! (disambiguation)" /> <l ns="0" title="!! 6- -.4rtist.com" /> <l ns="0" title="!!m" /> <l ns="0" title="!!suck my balls!!" /> <l ns="0" title="!!~~YOU WIN~~!!" /> <l ns="0" title="!'O-!khung language" /> <l ns="0" title="!(1)Full Name:(2)Age:(3)Sex:(4)Occupation:(5)Phone Number: (6)Delivery Address:(7)Country of Residence:. Dr.John Aboh" /> <l ns="0" title="!-" /> <l ns="0" title="!-My Degrassi Top 10 Episodes" /> <l ns="0" title="!10 Show" /> <l ns="0" title="!2005" /> <l ns="0" title="!2006" /> </alllinks> </query> <query-continue> <revisions rvstartid="366673948" /> <alllinks alfrom="!2009" /> </query-continue> </api> As you can see if you look at the <alllinks> part, its just a load of random gobbledy-gook. No nearly what I thought I'd get. I've done a fair bit of searching but I can't seem to find a direct answer to my question. What should the list=alllinks option return? Why am I getting this crap in there? Thanks for your help

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Generic Aggregation of C++ Objects by Attribute When Attribute Name is Unknown at Runtime

- by stretch

I'm currently implementing a system with a number of class's representing objects such as client, business, product etc. Standard business logic. As one might expect each class has a number of standard attributes. I have a long list of essentially identical requirements such as: the ability to retrieve all business' whose industry is manufacturing. the ability to retrieve all clients based in London Class business has attribute sector and client has attribute location. Clearly this a relational problem and in pseudo SQL would look something like: SELECT ALL business in business' WHERE sector == manufacturing Unfortunately plugging into a DB is not an option. What I want to do is have a single generic aggregation function whose signature would take the form: vector<generic> genericAggregation(class, attribute, value); Where class is the class of object I want to aggregate, attribute and value being the class attribute and value of interest. In my example I've put vector as return type, but this wouldn't work. Probably better to declare a vector of relevant class type and pass it as an argument. But this isn't the main problem. How can I accept arguments in string form for class, attribute and value and then map these in a generic object aggregation function? Since it's rude not to post code, below is a dummy program which creates a bunch of objects of imaginatively named classes. Included is a specific aggregation function which returns a vector of B objects whose A object is equal to an id specified at the command line e.g. .. $ ./aggregations 5 which returns all B's whose A objects 'i' attribute is equal to 5. See below: #include <iostream> #include <cstring> #include <sstream> #include <vector> using namespace std; //First imaginativly names dummy class class A { private: int i; double d; string s; public: A(){} A(int i, double d, string s) { this->i = i; this->d = d; this->s = s; } ~A(){} int getInt() {return i;} double getDouble() {return d;} string getString() {return s;} }; //second imaginativly named dummy class class B { private: int i; double d; string s; A *a; public: B(int i, double d, string s, A *a) { this->i = i; this->d = d; this->s = s; this->a = a; } ~B(){} int getInt() {return i;} double getDouble() {return d;} string getString() {return s;} A* getA() {return a;} }; //Containers for dummy class objects vector<A> a_vec (10); vector<B> b_vec;//100 //Util function, not important.. string int2string(int number) { stringstream ss; ss << number; return ss.str(); } //Example function that returns a new vector containing on B objects //whose A object i attribute is equal to 'id' vector<B> getBbyA(int id) { vector<B> result; for(int i = 0; i < b_vec.size(); i++) { if(b_vec.at(i).getA()->getInt() == id) { result.push_back(b_vec.at(i)); } } return result; } int main(int argc, char** argv) { //Create some A's and B's, each B has an A... //Each of the 10 A's are associated with 10 B's. for(int i = 0; i < 10; ++i) { A a(i, (double)i, int2string(i)); a_vec.at(i) = a; for(int j = 0; j < 10; j++) { B b((i * 10) + j, (double)j, int2string(i), &a_vec.at(i)); b_vec.push_back(b); } } //Got some objects so lets do some aggregation //Call example aggregation function to return all B objects //whose A object has i attribute equal to argv[1] vector<B> result = getBbyA(atoi(argv[1])); //If some B's were found print them, else don't... if(result.size() != 0) { for(int i = 0; i < result.size(); i++) { cout << result.at(i).getInt() << " " << result.at(i).getA()->getInt() << endl; } } else { cout << "No B's had A's with attribute i equal to " << argv[1] << endl; } return 0; } Compile with: g++ -o aggregations aggregations.cpp If you wish :) Instead of implementing a separate aggregation function (i.e. getBbyA() in the example) I'd like to have a single generic aggregation function which accounts for all possible class attribute pairs such that all aggregation requirements are met.. and in the event additional attributes are added later, or additional aggregation requirements, these will automatically be accounted for. So there's a few issues here but the main one I'm seeking insight into is how to map a runtime argument to a class attribute. I hope I've provided enough detail to adequately describe what I'm trying to do...

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Implementing a robust async stream reader

- by Jon

I recently provided an answer to this question: C# - Realtime console output redirection. As often happens, explaining stuff (here "stuff" was how I tackled a similar problem) leads you to greater understanding and/or, as is the case here, "oops" moments. I realized that my solution, as implemented, has a bug. The bug has little practical importance, but it has an extremely large importance to me as a developer: I can't rest easy knowing that my code has the potential to blow up. Squashing the bug is the purpose of this question. I apologize for the long intro, so let's get dirty. I wanted to build a class that allows me to receive input from a Stream in an event-based manner. The stream, in my scenario, is guaranteed to be a FileStream and there is also an associated StreamReader already present to leverage. The public interface of the class is this: public class MyStreamManager { public event EventHandler<ConsoleOutputReadEventArgs> StandardOutputRead; public void StartSendingEvents(); public void StopSendingEvents(); } Obviously this specific scenario has to do with a console's standard output, but that is a detail and does not play an important role. StartSendingEvents and StopSendingEvents do what they advertise; for the purposes of this discussion, we can assume that events are always being sent without loss of generality. The class uses these two fields internally: protected readonly StringBuilder inputAccumulator = new StringBuilder(); protected readonly byte[] buffer = new byte[256]; The functionality of the class is implemented in the methods below. To get the ball rolling: public void StartSendingEvents(); { this.stopAutomation = false; this.BeginReadAsync(); } To read data out of the Stream without blocking, and also without requiring a carriage return char, BeginRead is called: protected void BeginReadAsync() { if (!this.stopAutomation) { this.StandardOutput.BaseStream.BeginRead( this.buffer, 0, this.buffer.Length, this.ReadHappened, null); } } The challenging part: BeginRead requires using a buffer. This means that when reading from the stream, it is possible that the bytes available to read ("incoming chunk") are larger than the buffer. Since we are only handing off data from the stream to a consumer, and that consumer may well have inside knowledge about the size and/or format of these chunks, I want to call event subscribers exactly once for each chunk. Otherwise the abstraction breaks down and the subscribers have to buffer the incoming data and reconstruct the chunks themselves using said knowledge. This is much less convenient to the calling code, and detracts from the usefulness of my class. To this end, if the buffer is full after EndRead, we don't send its contents to subscribers immediately but instead append them to a StringBuilder. The contents of the StringBuilder are only sent back whenever there is no more to read from the stream (thus preserving the chunks). private void ReadHappened(IAsyncResult asyncResult) { var bytesRead = this.StandardOutput.BaseStream.EndRead(asyncResult); if (bytesRead == 0) { this.OnAutomationStopped(); return; } var input = this.StandardOutput.CurrentEncoding.GetString( this.buffer, 0, bytesRead); this.inputAccumulator.Append(input); if (bytesRead < this.buffer.Length) { this.OnInputRead(); // only send back if we 're sure we got it all } this.BeginReadAsync(); // continue "looping" with BeginRead } After any read which is not enough to fill the buffer, all accumulated data is sent to the subscribers: private void OnInputRead() { var handler = this.StandardOutputRead; if (handler == null) { return; } handler(this, new ConsoleOutputReadEventArgs(this.inputAccumulator.ToString())); this.inputAccumulator.Clear(); } (I know that as long as there are no subscribers the data gets accumulated forever. This is a deliberate decision). The good This scheme works almost perfectly: Async functionality without spawning any threads Very convenient to the calling code (just subscribe to an event) Maintains the "chunkiness" of the data; this allows the calling code to use inside knowledge of the data without doing any extra work Is almost agnostic to the buffer size (it will work correctly with any size buffer irrespective of the data being read) The bad That last almost is a very big one. Consider what happens when there is an incoming chunk with length exactly equal to the size of the buffer. The chunk will be read and buffered, but the event will not be triggered. This will be followed up by a BeginRead that expects to find more data belonging to the current chunk in order to send it back all in one piece, but... there will be no more data in the stream. In fact, as long as data is put into the stream in chunks with length exactly equal to the buffer size, the data will be buffered and the event will never be triggered. This scenario may be highly unlikely to occur in practice, especially since we can pick any number for the buffer size, but the problem is there. Solution? Unfortunately, after checking the available methods on FileStream and StreamReader, I can't find anything which lets me peek into the stream while also allowing async methods to be used on it. One "solution" would be to have a thread wait on a ManualResetEvent after the "buffer filled" condition is detected. If the event is not signaled (by the async callback) in a small amount of time, then more data from the stream will not be forthcoming and the data accumulated so far should be sent to subscribers. However, this introduces the need for another thread, requires thread synchronization, and is plain inelegant. Specifying a timeout for BeginRead would also suffice (call back into my code every now and then so I can check if there's data to be sent back; most of the time there will not be anything to do, so I expect the performance hit to be negligible). But it looks like timeouts are not supported in FileStream. Since I imagine that async calls with timeouts are an option in bare Win32, another approach might be to PInvoke the hell out of the problem. But this is also undesirable as it will introduce complexity and simply be a pain to code. Is there an elegant way to get around the problem? Thanks for being patient enough to read all of this.

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Setting an XAML Window always on top (but no TopMost property)

- by Brian Scherady

I am developing an application based on OptiTrack SDK (from NaturalPoint). I need to run the application window as "Always on Top". The window is designed in XAML and is controled in the class "CameraView" but it does not seem to include a "TopMost" property or equivalent. Attached are the code of "CameraView.xaml.cs" and the code of "CameraView.xaml" that are part of OptiTrack SDK (NaturalPoint) called "Single_Camera_CSharp_.NET_3.0". One could expect the class CameraView to contain properties or members to set the position of the window on the screen or to set it to TopMost but as far as searched I found nothing. I wonder what I should do. Thank you, Brian ================ "CameraView.xaml.cs" using System; using System.IO; using System.Net; using System.Windows; using System.Windows.Controls; using System.Windows.Data; using System.Windows.Media; using System.Windows.Media.Animation; using System.Windows.Navigation; using System.Drawing.Imaging; using System.Drawing.Drawing2D; using System.Windows.Threading; namespace TestProject { public partial class CameraView { private const int NP_OPTION_OBJECT_COLOR_OPTION = 3; private const int NP_OPTION_VIDEO_TYPE = 48; private const int NP_OPTION_NUMERIC_DISPLAY_ON = 71; private const int NP_OPTION_NUMERIC_DISPLAY_OFF = 72; private const int NP_OPTION_FETCH_RLE = 73; private const int NP_OPTION_FETCH_GRAYSCALE = 74; private const int NP_OPTION_FRAME_DECIMATION = 52; private const int NP_OPTION_INTENSITY = 50; private const int NP_OPTION_SEND_EMPTY_FRAMES = 41; private const int NP_OPTION_THRESHOLD = 5; private const int NP_OPTION_EXPOSURE = 46; private const int NP_OPTION_SEND_FRAME_MASK = 73; private const int NP_OPTION_TEXT_OVERLAY_OPTION = 74; // public delegate void OnCameraViewCreate(CameraView camera); // public static OnCameraViewCreate onCameraViewCreate; private System.Drawing.Bitmap raw = new System.Drawing.Bitmap(353, 288, System.Drawing.Imaging.PixelFormat.Format32bppArgb); private int mFrameCounter; private int mDisplayCounter; private DispatcherTimer timer1 = new DispatcherTimer(); private bool mVideoFrameAvailable = false; private int mNumeric = -1; private bool mGreyscale = false; private bool mOverlay = true; public CameraView() { this.InitializeComponent(); timer1.Interval = new TimeSpan(0, 0, 0, 0, 10); timer1.Tick += new EventHandler(timer1_Tick); } public int Numeric { get { return mNumeric; } set { mNumeric = value % 100; if (mNumeric = 0) { if (Camera != null) Camera.SetOption(NP_OPTION_NUMERIC_DISPLAY_ON, value % 100); } } } private bool CameraRunning = false; private OptiTrack.NPCamera mCamera; public OptiTrack.NPCamera Camera { get { return mCamera; } set { if (mCamera == value) return; //== Don't do anything if you're assigning the same camera == if (mCamera != null) { //== Shut the selected camera down ==<< if (CameraRunning) { CameraRunning = false; mCamera.Stop(); mCamera.FrameAvailable -= FrameAvailable; } } mCamera = value; if (mCamera == null) { mNumeric = -1; } else { serialLabel.Content = "Camera "+mCamera.SerialNumber.ToString(); //mNumeric.ToString(); } } } private void FrameAvailable(OptiTrack.NPCamera Camera) { mFrameCounter++; try { OptiTrack.NPCameraFrame frame = Camera.GetFrame(0); int id = frame.Id; if (CameraRunning) { GetFrameData(Camera, frame); } frame.Free(); } catch (Exception) { int r = 0; r++; } } private void GetFrameData(OptiTrack.NPCamera camera, OptiTrack.NPCameraFrame frame) { BitmapData bmData = raw.LockBits(new System.Drawing.Rectangle(0, 0, raw.Width, raw.Height), ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format32bppArgb); int stride = bmData.Stride; System.IntPtr bufferPtr = bmData.Scan0; unsafe { byte* buffer = (byte*)(void*)bufferPtr; camera.GetFrameImage(frame, bmData.Width, bmData.Height, bmData.Stride, 32, ref buffer[0]); } raw.UnlockBits(bmData); mVideoFrameAvailable = true; } private void timer1_Tick(object sender, EventArgs e) { if (CameraRunning && mVideoFrameAvailable) { mVideoFrameAvailable = false; cameraImage.Source = Img(raw); mDisplayCounter++; } } private System.Windows.Media.ImageSource Img(System.Drawing.Bitmap img) { System.Drawing.Imaging.BitmapData bmData = img.LockBits(new System.Drawing.Rectangle(0, 0, img.Width, img.Height), System.Drawing.Imaging.ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format32bppPArgb); System.Windows.Media.Imaging.BitmapSource bitmap = System.Windows.Media.Imaging.BitmapSource.Create( img.Width, img.Height, 96, 96, PixelFormats.Bgra32, System.Windows.Media.Imaging.BitmapPalettes.WebPalette, bmData.Scan0, bmData.Stride * bmData.Height, bmData.Stride); img.UnlockBits(bmData); return bitmap; } private void startStopButton_Click(object sender, RoutedEventArgs e) { if (CameraRunning) StopCamera(); else StartCamera(); } public void StartCamera() { if (Camera != null) { mFrameCounter = 0; mDisplayCounter = 0; Camera.FrameAvailable += FrameAvailable; Camera.SetOption(NP_OPTION_VIDEO_TYPE, 0); Camera.SetOption(NP_OPTION_FRAME_DECIMATION, 1); Camera.SetOption(NP_OPTION_INTENSITY, 0); Camera.SetOption(NP_OPTION_EXPOSURE, 10); Camera.SetOption(NP_OPTION_THRESHOLD, 50); Camera.SetOption(NP_OPTION_OBJECT_COLOR_OPTION, 0); SetOverlayOption(); SetGreyscaleOption(); timer1.Start(); Camera.Start(); CameraRunning = true; this.Numeric = mNumeric; startStopButton.Content = "Stop Camera"; } } private void SetGreyscaleOption() { if(mGreyscale) Camera.SetOption(NP_OPTION_VIDEO_TYPE, 1); else Camera.SetOption(NP_OPTION_VIDEO_TYPE, 0); } private void SetOverlayOption() { if(mOverlay) Camera.SetOption(NP_OPTION_TEXT_OVERLAY_OPTION, 255); else Camera.SetOption(NP_OPTION_TEXT_OVERLAY_OPTION, 0); } public void StopCamera() { if (Camera != null) { Camera.Stop(); timer1.Stop(); CameraRunning = false; Camera.FrameAvailable -= FrameAvailable; Camera.SetOption(NP_OPTION_NUMERIC_DISPLAY_OFF, 0); startStopButton.Content = "Start Camera"; } } private void greyscaleButton_Click(object sender, RoutedEventArgs e) { if(mGreyscale) mGreyscale = false; else mGreyscale = true; SetGreyscaleOption(); } private void OverlayButton_Click(object sender, RoutedEventArgs e) { if(mOverlay) mOverlay = false; else mOverlay = true; SetOverlayOption(); } private void exposureSlider_ValueChanged(object sender, RoutedEventArgs e) { if (mCamera!=null) { mCamera.SetOption(NP_OPTION_EXPOSURE, (int) this.exposureSlider.Value); } } private void thresholdSlider_ValueChanged(object sender, RoutedEventArgs e) { if (mCamera != null) { mCamera.SetOption(NP_OPTION_THRESHOLD, (int)this.thresholdSlider.Value); } } private void optionsButton_Click(object sender, RoutedEventArgs e) { if (!propertyPanel.IsVisible) propertyPanel.Visibility = Visibility.Visible; else propertyPanel.Visibility = Visibility.Collapsed; } } } ================ "CameraView.xaml"

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C++ simple logging class with UTF-8 output [code example]

- by Andrew

Hello everyone, I was working on one of my academic projects and for the first time I needed pure C++ without GUI. After googling for a while, I did not find any simple and easy to use implementation for logging and created my own. This is a simple implementation with iostreams that logs messages to screen and to the file simultaneously. I was thinking of using templates but then I realized that I do not expect any changes and removed that. It is modified std::wostream with two added modifiers: 1. TimeStamp - prints time-stamp 2. LogMode(LogModes) - switches output: file only, screen only, file+screen. *Boost::utf8_codecvt_facet* is used for UTF-8 output. // ############################################################################ // # Name: MyLog.h # // # Purpose: Logging Class Header # // # Author: Andrew Drach # // # Modified by: <somebody> # // # Created: 03/21/10 # // # SVN-ID: $Id$ # // # Copyright: (c) 2010 Andrew Drach # // # Licence: <license> # // ############################################################################ #ifndef INCLUDED_MYLOG_H #define INCLUDED_MYLOG_H // headers -------------------------------------------------------------------- #include <string> #include <iostream> #include <fstream> #include <exception> #include <boost/program_options/detail/utf8_codecvt_facet.hpp> using namespace std; // definitions ---------------------------------------------------------------- // ---------------------------------------------------------------------------- // DblBuf class // Splits up output stream into two // Inspired by http://wordaligned.org/articles/cpp-streambufs // ---------------------------------------------------------------------------- class DblBuf : public wstreambuf { private: // private member declarations DblBuf(); wstreambuf *bf1; wstreambuf *bf2; virtual int_type overflow(int_type ch) { int_type eof = traits_type::eof(); int_type not_eof = !eof; if ( traits_type::eq_int_type(ch,eof) ) return not_eof; else { char_type ch1 = traits_type::to_char_type(ch); int_type r1( bf1on ? bf1->sputc(ch1) : not_eof ); int_type r2( bf2on ? bf2->sputc(ch1) : not_eof ); return (traits_type::eq_int_type(r1,eof) || traits_type::eq_int_type(r2,eof) ) ? eof : ch; } } virtual int sync() { int r1( bf1on ? bf1->pubsync() : NULL ); int r2( bf2on ? bf2->pubsync() : NULL ); return (r1 == 0 && r2 == 0) ? 0 : -1; } public: // public member declarations explicit DblBuf(wstreambuf *bf1, wstreambuf *bf2) : bf1(bf1), bf2(bf2) { if (bf1) bf1on = true; else bf1on = false; if (bf2) bf2on = true; else bf2on = false; } bool bf1on; bool bf2on; }; // ---------------------------------------------------------------------------- // logstream class // Wrapper for a standard wostream with access to modified buffer // ---------------------------------------------------------------------------- class logstream : public wostream { private: // private member declarations logstream(); public: // public member declarations DblBuf *buf; explicit logstream(wstreambuf *StrBuf, bool isStd = false) : wostream(StrBuf, isStd), buf((DblBuf*)StrBuf) {} }; // ---------------------------------------------------------------------------- // Logging mode Class // ---------------------------------------------------------------------------- enum LogModes{LogToFile=1, LogToScreen, LogToBoth}; class LogMode { private: // private member declarations LogMode(); short mode; public: // public member declarations LogMode(short mode1) : mode(mode1) {} logstream& operator()(logstream &stream1) { switch(mode) { case LogToFile: stream1.buf->bf1on = true; stream1.buf->bf2on = false; break; case LogToScreen: stream1.buf->bf1on = false; stream1.buf->bf2on = true; break; case LogToBoth: stream1.buf->bf1on = true; stream1.buf->bf2on = true; } return stream1; } }; logstream& operator<<(logstream &out, LogMode mode) { return mode(out); } wostream& TimeStamp1(wostream &out1) { time_t time1; struct tm timeinfo; wchar_t timestr[512]; // Get current time and convert it to a string time(&time1); localtime_s (&timeinfo, &time1); wcsftime(timestr, 512,L"[%Y-%b-%d %H:%M:%S %p] ",&timeinfo); return out1 << timestr; } // ---------------------------------------------------------------------------- // MyLog class // Logs events to both file and screen // ---------------------------------------------------------------------------- class MyLog { private: // private member declarations MyLog(); auto_ptr<DblBuf> buf; string mErrorMsg1; string mErrorMsg2; string mErrorMsg3; string mErrorMsg4; public: // public member declarations explicit MyLog(string FileName1, wostream *ScrLog1, locale utf8locale1); ~MyLog(); void NewEvent(wstring str1, bool TimeStamp = true); string FileName; wostream *ScrLog; wofstream File; auto_ptr<logstream> Log; locale utf8locale; }; // ---------------------------------------------------------------------------- // MyLog constructor // ---------------------------------------------------------------------------- MyLog::MyLog(string FileName1, wostream *ScrLog1, locale utf8locale1) : // ctors mErrorMsg1("Failed to open file for application logging! []"), mErrorMsg2("Failed to write BOM! []"), mErrorMsg3("Failed to write to file! []"), mErrorMsg4("Failed to close file! []"), FileName(FileName1), ScrLog(ScrLog1), utf8locale(utf8locale1), File(FileName1.c_str()) { // Adjust error strings mErrorMsg1.insert(mErrorMsg1.length()-1,FileName1); mErrorMsg2.insert(mErrorMsg2.length()-1,FileName1); mErrorMsg3.insert(mErrorMsg3.length()-1,FileName1); mErrorMsg4.insert(mErrorMsg4.length()-1,FileName1); // check for file open errors if ( !File ) throw ofstream::failure(mErrorMsg1); // write UTF-8 BOM File << wchar_t(0xEF) << wchar_t(0xBB) << wchar_t(0xBF); // switch locale to UTF-8 File.imbue(utf8locale); // check for write errors if ( File.bad() ) throw ofstream::failure(mErrorMsg2); buf.reset( new DblBuf(File.rdbuf(),ScrLog->rdbuf()) ); Log.reset( new logstream(&*buf) ); } // ---------------------------------------------------------------------------- // MyLog destructor // ---------------------------------------------------------------------------- MyLog::~MyLog() { *Log << TimeStamp1 << "Log finished." << endl; // clean up objects Log.reset(); buf.reset(); File.close(); // check for file close errors if ( File.bad() ) throw ofstream::failure(mErrorMsg4); } //--------------------------------------------------------------------------- #endif // INCLUDED_MYLOG_H Tested on MSVC 2008, boost 1.42. I do not know if this is the right place to share it. Hope it helps anybody. Feel free to make it better.

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Implementing a robust async stream reader for a console

- by Jon

I recently provided an answer to this question: C# - Realtime console output redirection. As often happens, explaining stuff (here "stuff" was how I tackled a similar problem) leads you to greater understanding and/or, as is the case here, "oops" moments. I realized that my solution, as implemented, has a bug. The bug has little practical importance, but it has an extremely large importance to me as a developer: I can't rest easy knowing that my code has the potential to blow up. Squashing the bug is the purpose of this question. I apologize for the long intro, so let's get dirty. I wanted to build a class that allows me to receive input from a Stream in an event-based manner. The stream, in my scenario, is guaranteed to be a FileStream and there is also an associated StreamReader already present to leverage. The public interface of the class is this: public class MyStreamManager { public event EventHandler<ConsoleOutputReadEventArgs> StandardOutputRead; public void StartSendingEvents(); public void StopSendingEvents(); } Obviously this specific scenario has to do with a console's standard output. StartSendingEvents and StopSendingEvents do what they advertise; for the purposes of this discussion, we can assume that events are always being sent without loss of generality. The class uses these two fields internally: protected readonly StringBuilder inputAccumulator = new StringBuilder(); protected readonly byte[] buffer = new byte[256]; The functionality of the class is implemented in the methods below. To get the ball rolling: public void StartSendingEvents(); { this.stopAutomation = false; this.BeginReadAsync(); } To read data out of the Stream without blocking, and also without requiring a carriage return char, BeginRead is called: protected void BeginReadAsync() { if (!this.stopAutomation) { this.StandardOutput.BaseStream.BeginRead( this.buffer, 0, this.buffer.Length, this.ReadHappened, null); } } The challenging part: BeginRead requires using a buffer. This means that when reading from the stream, it is possible that the bytes available to read ("incoming chunk") are larger than the buffer. Since we are only handing off data from the stream to a consumer, and that consumer may well have inside knowledge about the size and/or format of these chunks, I want to call event subscribers exactly once for each chunk. Otherwise the abstraction breaks down and the subscribers have to buffer the incoming data and reconstruct the chunks themselves using said knowledge. This is much less convenient to the calling code, and detracts from the usefulness of my class. Edit: There are comments below correctly stating that since the data is coming from a stream, there is absolutely nothing that the receiver can infer about the structure of the data unless it is fully prepared to parse it. What I am trying to do here is leverage the "flush the output" "structure" that the owner of the console imparts while writing on it. I am prepared to assume (better: allow my caller to have the option to assume) that the OS will pass me the data written between two flushes of the stream in exactly one piece. To this end, if the buffer is full after EndRead, we don't send its contents to subscribers immediately but instead append them to a StringBuilder. The contents of the StringBuilder are only sent back whenever there is no more to read from the stream (thus preserving the chunks). private void ReadHappened(IAsyncResult asyncResult) { var bytesRead = this.StandardOutput.BaseStream.EndRead(asyncResult); if (bytesRead == 0) { this.OnAutomationStopped(); return; } var input = this.StandardOutput.CurrentEncoding.GetString( this.buffer, 0, bytesRead); this.inputAccumulator.Append(input); if (bytesRead < this.buffer.Length) { this.OnInputRead(); // only send back if we 're sure we got it all } this.BeginReadAsync(); // continue "looping" with BeginRead } After any read which is not enough to fill the buffer, all accumulated data is sent to the subscribers: private void OnInputRead() { var handler = this.StandardOutputRead; if (handler == null) { return; } handler(this, new ConsoleOutputReadEventArgs(this.inputAccumulator.ToString())); this.inputAccumulator.Clear(); } (I know that as long as there are no subscribers the data gets accumulated forever. This is a deliberate decision). The good This scheme works almost perfectly: Async functionality without spawning any threads Very convenient to the calling code (just subscribe to an event) Maintains the "chunkiness" of the data; this allows the calling code to use inside knowledge of the data without doing any extra work Is almost agnostic to the buffer size (it will work correctly with any size buffer irrespective of the data being read) The bad That last almost is a very big one. Consider what happens when there is an incoming chunk with length exactly equal to the size of the buffer. The chunk will be read and buffered, but the event will not be triggered. This will be followed up by a BeginRead that expects to find more data belonging to the current chunk in order to send it back all in one piece, but... there will be no more data in the stream. In fact, as long as data is put into the stream in chunks with length exactly equal to the buffer size, the data will be buffered and the event will never be triggered. This scenario may be highly unlikely to occur in practice, especially since we can pick any number for the buffer size, but the problem is there. Solution? Unfortunately, after checking the available methods on FileStream and StreamReader, I can't find anything which lets me peek into the stream while also allowing async methods to be used on it. One "solution" would be to have a thread wait on a ManualResetEvent after the "buffer filled" condition is detected. If the event is not signaled (by the async callback) in a small amount of time, then more data from the stream will not be forthcoming and the data accumulated so far should be sent to subscribers. However, this introduces the need for another thread, requires thread synchronization, and is plain inelegant. Specifying a timeout for BeginRead would also suffice (call back into my code every now and then so I can check if there's data to be sent back; most of the time there will not be anything to do, so I expect the performance hit to be negligible). But it looks like timeouts are not supported in FileStream. Since I imagine that async calls with timeouts are an option in bare Win32, another approach might be to PInvoke the hell out of the problem. But this is also undesirable as it will introduce complexity and simply be a pain to code. Is there an elegant way to get around the problem? Thanks for being patient enough to read all of this.

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Linked List manipulation, issues retrieving data c++

- by floatfil

I'm trying to implement some functions to manipulate a linked list. The implementation is a template typename T and the class is 'List' which includes a 'head' pointer and also a struct: struct Node { // the node in a linked list T* data; // pointer to actual data, operations in T Node* next; // pointer to a Node }; Since it is a template, and 'T' can be any data, how do I go about checking the data of a list to see if it matches the data input into the function? The function is called 'retrieve' and takes two parameters, the data and a pointer: bool retrieve(T target, T*& ptr); // This is the prototype we need to use for the project "bool retrieve : similar to remove, but not removed from list. If there are duplicates in the list, the first one encountered is retrieved. Second parameter is unreliable if return value is false. E.g., " Employee target("duck", "donald"); success = company1.retrieve(target, oneEmployee); if (success) { cout << "Found in list: " << *oneEmployee << endl; } And the function is called like this: company4.retrieve(emp3, oneEmployee) So that when you cout *oneEmployee, you'll get the data of that pointer (in this case the data is of type Employee). (Also, this is assuming all data types have the apropriate overloaded operators) I hope this makes sense so far, but my issue is in comparing the data in the parameter and the data while going through the list. (The data types that we use all include overloads for equality operators, so oneData == twoData is valid) This is what I have so far: template <typename T> bool List<T>::retrieve(T target , T*& ptr) { List<T>::Node* dummyPtr = head; // point dummy pointer to what the list's head points to for(;;) { if (*dummyPtr->data == target) { // EDIT: it now compiles, but it breaks here and I get an Access Violation error. ptr = dummyPtr->data; // set the parameter pointer to the dummy pointer return true; // return true } else { dummyPtr = dummyPtr->next; // else, move to the next data node } } return false; } Here is the implementation for the Employee class: //-------------------------- constructor ----------------------------------- Employee::Employee(string last, string first, int id, int sal) { idNumber = (id >= 0 && id <= MAXID? id : -1); salary = (sal >= 0 ? sal : -1); lastName = last; firstName = first; } //-------------------------- destructor ------------------------------------ // Needed so that memory for strings is properly deallocated Employee::~Employee() { } //---------------------- copy constructor ----------------------------------- Employee::Employee(const Employee& E) { lastName = E.lastName; firstName = E.firstName; idNumber = E.idNumber; salary = E.salary; } //-------------------------- operator= --------------------------------------- Employee& Employee::operator=(const Employee& E) { if (&E != this) { idNumber = E.idNumber; salary = E.salary; lastName = E.lastName; firstName = E.firstName; } return *this; } //----------------------------- setData ------------------------------------ // set data from file bool Employee::setData(ifstream& inFile) { inFile >> lastName >> firstName >> idNumber >> salary; return idNumber >= 0 && idNumber <= MAXID && salary >= 0; } //------------------------------- < ---------------------------------------- // < defined by value of name bool Employee::operator<(const Employee& E) const { return lastName < E.lastName || (lastName == E.lastName && firstName < E.firstName); } //------------------------------- <= ---------------------------------------- // < defined by value of inamedNumber bool Employee::operator<=(const Employee& E) const { return *this < E || *this == E; } //------------------------------- > ---------------------------------------- // > defined by value of name bool Employee::operator>(const Employee& E) const { return lastName > E.lastName || (lastName == E.lastName && firstName > E.firstName); } //------------------------------- >= ---------------------------------------- // < defined by value of name bool Employee::operator>=(const Employee& E) const { return *this > E || *this == E; } //----------------- operator == (equality) ---------------- // if name of calling and passed object are equal, // return true, otherwise false // bool Employee::operator==(const Employee& E) const { return lastName == E.lastName && firstName == E.firstName; } //----------------- operator != (inequality) ---------------- // return opposite value of operator== bool Employee::operator!=(const Employee& E) const { return !(*this == E); } //------------------------------- << --------------------------------------- // display Employee object ostream& operator<<(ostream& output, const Employee& E) { output << setw(4) << E.idNumber << setw(7) << E.salary << " " << E.lastName << " " << E.firstName << endl; return output; } I will include a check for NULL pointer but I just want to get this working and will test it on a list that includes the data I am checking. Thanks to whoever can help and as usual, this is for a course so I don't expect or want the answer, but any tips as to what might be going wrong will help immensely!

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What's New in ASP.NET 4

- by Navaneeth

The .NET Framework version 4 includes enhancements for ASP.NET 4 in targeted areas. Visual Studio 2010 and Microsoft Visual Web Developer Express also include enhancements and new features for improved Web development. This document provides an overview of many of the new features that are included in the upcoming release. This topic contains the following sections: ASP.NET Core Services ASP.NET Web Forms ASP.NET MVC Dynamic Data ASP.NET Chart Control Visual Web Developer Enhancements Web Application Deployment with Visual Studio 2010 Enhancements to ASP.NET Multi-Targeting ASP.NET Core Services ASP.NET 4 introduces many features that improve core ASP.NET services such as output caching and session state storage. Extensible Output Caching Since the time that ASP.NET 1.0 was released, output caching has enabled developers to store the generated output of pages, controls, and HTTP responses in memory. On subsequent Web requests, ASP.NET can serve content more quickly by retrieving the generated output from memory instead of regenerating the output from scratch. However, this approach has a limitation — generated content always has to be stored in memory. On servers that experience heavy traffic, the memory requirements for output caching can compete with memory requirements for other parts of a Web application. ASP.NET 4 adds extensibility to output caching that enables you to configure one or more custom output-cache providers. Output-cache providers can use any storage mechanism to persist HTML content. These storage options can include local or remote disks, cloud storage, and distributed cache engines. Output-cache provider extensibility in ASP.NET 4 lets you design more aggressive and more intelligent output-caching strategies for Web sites. For example, you can create an output-cache provider that caches the "Top 10" pages of a site in memory, while caching pages that get lower traffic on disk. Alternatively, you can cache every vary-by combination for a rendered page, but use a distributed cache so that the memory consumption is offloaded from front-end Web servers. You create a custom output-cache provider as a class that derives from the OutputCacheProvider type. You can then configure the provider in the Web.config file by using the new providers subsection of the outputCache element For more information and for examples that show how to configure the output cache, see outputCache Element for caching (ASP.NET Settings Schema). For more information about the classes that support caching, see the documentation for the OutputCache and OutputCacheProvider classes. By default, in ASP.NET 4, all HTTP responses, rendered pages, and controls use the in-memory output cache. The defaultProvider attribute for ASP.NET is AspNetInternalProvider. You can change the default output-cache provider used for a Web application by specifying a different provider name for defaultProvider attribute. In addition, you can select different output-cache providers for individual control and for individual requests and programmatically specify which provider to use. For more information, see the HttpApplication.GetOutputCacheProviderName(HttpContext) method. The easiest way to choose a different output-cache provider for different Web user controls is to do so declaratively by using the new providerName attribute in a page or control directive, as shown in the following example: <%@ OutputCache Duration="60" VaryByParam="None" providerName="DiskCache" %> Preloading Web Applications Some Web applications must load large amounts of data or must perform expensive initialization processing before serving the first request. In earlier versions of ASP.NET, for these situations you had to devise custom approaches to "wake up" an ASP.NET application and then run initialization code during the Application_Load method in the Global.asax file. To address this scenario, a new application preload manager (autostart feature) is available when ASP.NET 4 runs on IIS 7.5 on Windows Server 2008 R2. The preload feature provides a controlled approach for starting up an application pool, initializing an ASP.NET application, and then accepting HTTP requests. It lets you perform expensive application initialization prior to processing the first HTTP request. For example, you can use the application preload manager to initialize an application and then signal a load-balancer that the application was initialized and ready to accept HTTP traffic. To use the application preload manager, an IIS administrator sets an application pool in IIS 7.5 to be automatically started by using the following configuration in the applicationHost.config file: <applicationPools> <add name="MyApplicationPool" startMode="AlwaysRunning" /> </applicationPools> Because a single application pool can contain multiple applications, you specify individual applications to be automatically started by using the following configuration in the applicationHost.config file: <sites> <site name="MySite" id="1"> <application path="/" serviceAutoStartEnabled="true" serviceAutoStartProvider="PrewarmMyCache" >  </application> </site> </sites>  <serviceAutoStartProviders> <add name="PrewarmMyCache" type="MyNamespace.CustomInitialization, MyLibrary" /> </serviceAutoStartProviders> When an IIS 7.5 server is cold-started or when an individual application pool is recycled, IIS 7.5 uses the information in the applicationHost.config file to determine which Web applications have to be automatically started. For each application that is marked for preload, IIS7.5 sends a request to ASP.NET 4 to start the application in a state during which the application temporarily does not accept HTTP requests. When it is in this state, ASP.NET instantiates the type defined by the serviceAutoStartProvider attribute (as shown in the previous example) and calls into its public entry point. You create a managed preload type that has the required entry point by implementing the IProcessHostPreloadClient interface, as shown in the following example: public class CustomInitialization : System.Web.Hosting.IProcessHostPreloadClient { public void Preload(string[] parameters) { // Perform initialization. } } After your initialization code runs in the Preload method and after the method returns, the ASP.NET application is ready to process requests. Permanently Redirecting a Page Content in Web applications is often moved over the lifetime of the application. This can lead to links to be out of date, such as the links that are returned by search engines. In ASP.NET, developers have traditionally handled requests to old URLs by using the Redirect method to forward a request to the new URL. However, the Redirect method issues an HTTP 302 (Found) response (which is used for a temporary redirect). This results in an extra HTTP round trip. ASP.NET 4 adds a RedirectPermanent helper method that makes it easy to issue HTTP 301 (Moved Permanently) responses, as in the following example: RedirectPermanent("/newpath/foroldcontent.aspx"); Search engines and other user agents that recognize permanent redirects will store the new URL that is associated with the content, which eliminates the unnecessary round trip made by the browser for temporary redirects. Session State Compression By default, ASP.NET provides two options for storing session state across a Web farm. The first option is a session state provider that invokes an out-of-process session state server. The second option is a session state provider that stores data in a Microsoft SQL Server database. Because both options store state information outside a Web application's worker process, session state has to be serialized before it is sent to remote storage. If a large amount of data is saved in session state, the size of the serialized data can become very large. ASP.NET 4 introduces a new compression option for both kinds of out-of-process session state providers. By using this option, applications that have spare CPU cycles on Web servers can achieve substantial reductions in the size of serialized session state data. You can set this option using the new compressionEnabled attribute of the sessionState element in the configuration file. When the compressionEnabled configuration option is set to true, ASP.NET compresses (and decompresses) serialized session state by using the .NET Framework GZipStreamclass. The following example shows how to set this attribute. <sessionState mode="SqlServer" sqlConnectionString="data source=dbserver;Initial Catalog=aspnetstate" allowCustomSqlDatabase="true" compressionEnabled="true" /> ASP.NET Web Forms Web Forms has been a core feature in ASP.NET since the release of ASP.NET 1.0. Many enhancements have been in this area for ASP.NET 4, such as the following: The ability to set meta tags. More control over view state. Support for recently introduced browsers and devices. Easier ways to work with browser capabilities. Support for using ASP.NET routing with Web Forms. More control over generated IDs. The ability to persist selected rows in data controls. More control over rendered HTML in the FormView and ListView controls. Filtering support for data source controls. Enhanced support for Web standards and accessibility Setting Meta Tags with the Page.MetaKeywords and Page.MetaDescription Properties Two properties have been added to the Page class: MetaKeywords and MetaDescription. These two properties represent corresponding meta tags in the HTML rendered for a page, as shown in the following example: <head id="Head1" runat="server"> <title>Untitled Page</title> <meta name="keywords" content="keyword1, keyword2' /> <meta name="description" content="Description of my page" /> </head> These two properties work like the Title property does, and they can be set in the @ Page directive. For more information, see Page.MetaKeywords and Page.MetaDescription. Enabling View State for Individual Controls A new property has been added to the Control class: ViewStateMode. You can use this property to disable view state for all controls on a page except those for which you explicitly enable view state. View state data is included in a page's HTML and increases the amount of time it takes to send a page to the client and post it back. Storing more view state than is necessary can cause significant decrease in performance. In earlier versions of ASP.NET, you could reduce the impact of view state on a page's performance by disabling view state for specific controls. But sometimes it is easier to enable view state for a few controls that need it instead of disabling it for many that do not need it. For more information, see Control.ViewStateMode. Support for Recently Introduced Browsers and Devices ASP.NET includes a feature that is named browser capabilities that lets you determine the capabilities of the browser that a user is using. Browser capabilities are represented by the HttpBrowserCapabilities object which is stored in the HttpRequest.Browser property. Information about a particular browser's capabilities is defined by a browser definition file. In ASP.NET 4, these browser definition files have been updated to contain information about recently introduced browsers and devices such as Google Chrome, Research in Motion BlackBerry smart phones, and Apple iPhone. Existing browser definition files have also been updated. For more information, see How to: Upgrade an ASP.NET Web Application to ASP.NET 4 and ASP.NET Web Server Controls and Browser Capabilities. The browser definition files that are included with ASP.NET 4 are shown in the following list: •blackberry.browser •chrome.browser •Default.browser •firefox.browser •gateway.browser •generic.browser •ie.browser •iemobile.browser •iphone.browser •opera.browser •safari.browser A New Way to Define Browser Capabilities ASP.NET 4 includes a new feature referred to as browser capabilities providers. As the name suggests, this lets you build a provider that in turn lets you write custom code to determine browser capabilities. In ASP.NET version 3.5 Service Pack 1, you define browser capabilities in an XML file. This file resides in a machine-level folder or an application-level folder. Most developers do not need to customize these files, but for those who do, the provider approach can be easier than dealing with complex XML syntax. The provider approach makes it possible to simplify the process by implementing a common browser definition syntax, or a database that contains up-to-date browser definitions, or even a Web service for such a database. For more information about the new browser capabilities provider, see the What's New for ASP.NET 4 White Paper. Routing in ASP.NET 4 ASP.NET 4 adds built-in support for routing with Web Forms. Routing is a feature that was introduced with ASP.NET 3.5 SP1 and lets you configure an application to use URLs that are meaningful to users and to search engines because they do not have to specify physical file names. This can make your site more user-friendly and your site content more discoverable by search engines. For example, the URL for a page that displays product categories in your application might look like the following example: http://website/products.aspx?categoryid=12 By using routing, you can use the following URL to render the same information: http://website/products/software The second URL lets the user know what to expect and can result in significantly improved rankings in search engine results. the new features include the following: The PageRouteHandler class is a simple HTTP handler that you use when you define routes. You no longer have to write a custom route handler. The HttpRequest.RequestContext and Page.RouteData properties make it easier to access information that is passed in URL parameters. The RouteUrl expression provides a simple way to create a routed URL in markup. The RouteValue expression provides a simple way to extract URL parameter values in markup. The RouteParameter class makes it easier to pass URL parameter values to a query for a data source control (similar to FormParameter). You no longer have to change the Web.config file to enable routing. For more information about routing, see the following topics: ASP.NET Routing Walkthrough: Using ASP.NET Routing in a Web Forms Application How to: Define Routes for Web Forms Applications How to: Construct URLs from Routes How to: Access URL Parameters in a Routed Page Setting Client IDs The new ClientIDMode property makes it easier to write client script that references HTML elements rendered for server controls. Increasing use of Microsoft Ajax makes the need to do this more common. For example, you may have a data control that renders a long list of products with prices and you want to use client script to make a Web service call and update individual prices in the list as they change without refreshing the entire page. Typically you get a reference to an HTML element in client script by using the document.GetElementById method. You pass to this method the value of the id attribute of the HTML element you want to reference. In the case of elements that are rendered for ASP.NET server controls earlier versions of ASP.NET could make this difficult or impossible. You were not always able to predict what id values ASP.NET would generate, or ASP.NET could generate very long id values. The problem was especially difficult for data controls that would generate multiple rows for a single instance of the control in your markup. ASP.NET 4 adds two new algorithms for generating id attributes. These algorithms can generate id attributes that are easier to work with in client script because they are more predictable and that are easier to work with because they are simpler. For more information about how to use the new algorithms, see the following topics: ASP.NET Web Server Control Identification Walkthrough: Making Data-Bound Controls Easier to Access from JavaScript Walkthrough: Making Controls Located in Web User Controls Easier to Access from JavaScript How to: Access Controls from JavaScript by ID Persisting Row Selection in Data Controls The GridView and ListView controls enable users to select a row. In previous versions of ASP.NET, row selection was based on the row index on the page. For example, if you select the third item on page 1 and then move to page 2, the third item on page 2 is selected. In most cases, is more desirable not to select any rows on page 2. ASP.NET 4 supports Persisted Selection, a new feature that was initially supported only in Dynamic Data projects in the .NET Framework 3.5 SP1. When this feature is enabled, the selected item is based on the row data key. This means that if you select the third row on page 1 and move to page 2, nothing is selected on page 2. When you move back to page 1, the third row is still selected. This is a much more natural behavior than the behavior in earlier versions of ASP.NET. Persisted selection is now supported for the GridView and ListView controls in all projects. You can enable this feature in the GridView control, for example, by setting the EnablePersistedSelection property, as shown in the following example: <asp:GridView id="GridView2" runat="server" PersistedSelection="true"> </asp:GridView> FormView Control Enhancements The FormView control is enhanced to make it easier to style the content of the control with CSS. In previous versions of ASP.NET, the FormView control rendered it contents using an item template. This made styling more difficult in the markup because unexpected table row and table cell tags were rendered by the control. The FormView control supports RenderOuterTable, a property in ASP.NET 4. When this property is set to false, as show in the following example, the table tags are not rendered. This makes it easier to apply CSS style to the contents of the control. <asp:FormView ID="FormView1" runat="server" RenderTable="false"> For more information, see FormView Web Server Control Overview. ListView Control Enhancements The ListView control, which was introduced in ASP.NET 3.5, has all the functionality of the GridView control while giving you complete control over the output. This control has been made easier to use in ASP.NET 4. The earlier version of the control required that you specify a layout template that contained a server control with a known ID. The following markup shows a typical example of how to use the ListView control in ASP.NET 3.5. <asp:ListView ID="ListView1" runat="server"> <LayoutTemplate> <asp:PlaceHolder ID="ItemPlaceHolder" runat="server"></asp:PlaceHolder> </LayoutTemplate> <ItemTemplate> <% Eval("LastName")%> </ItemTemplate> </asp:ListView> In ASP.NET 4, the ListView control does not require a layout template. The markup shown in the previous example can be replaced with the following markup: <asp:ListView ID="ListView1" runat="server"> <ItemTemplate> <% Eval("LastName")%> </ItemTemplate> </asp:ListView> For more information, see ListView Web Server Control Overview. Filtering Data with the QueryExtender Control A very common task for developers who create data-driven Web pages is to filter data. This traditionally has been performed by building Where clauses in data source controls. This approach can be complicated, and in some cases the Where syntax does not let you take advantage of the full functionality of the underlying database. To make filtering easier, a new QueryExtender control has been added in ASP.NET 4. This control can be added to EntityDataSource or LinqDataSource controls in order to filter the data returned by these controls. Because the QueryExtender control relies on LINQ, but you do not to need to know how to write LINQ queries to use the query extender. The QueryExtender control supports a variety of filter options. The following lists QueryExtender filter options. Term Definition SearchExpression Searches a field or fields for string values and compares them to a specified string value. RangeExpression Searches a field or fields for values in a range specified by a pair of values. PropertyExpression Compares a specified value to a property value in a field. If the expression evaluates to true, the data that is being examined is returned. OrderByExpression Sorts data by a specified column and sort direction. CustomExpression Calls a function that defines custom filter in the page. For more information, see QueryExtenderQueryExtender Web Server Control Overview. Enhanced Support for Web Standards and Accessibility Earlier versions of ASP.NET controls sometimes render markup that does not conform to HTML, XHTML, or accessibility standards. ASP.NET 4 eliminates most of these exceptions. For details about how the HTML that is rendered by each control meets accessibility standards, see ASP.NET Controls and Accessibility. CSS for Controls that Can be Disabled In ASP.NET 3.5, when a control is disabled (see WebControl.Enabled), a disabled attribute is added to the rendered HTML element. For example, the following markup creates a Label control that is disabled: <asp:Label id="Label1" runat="server" Text="Test" Enabled="false" /> In ASP.NET 3.5, the previous control settings generate the following HTML: <span id="Label1" disabled="disabled">Test</span> In HTML 4.01, the disabled attribute is not considered valid on span elements. It is valid only on input elements because it specifies that they cannot be accessed. On display-only elements such as span elements, browsers typically support rendering for a disabled appearance, but a Web page that relies on this non-standard behavior is not robust according to accessibility standards. For display-only elements, you should use CSS to indicate a disabled visual appearance. Therefore, by default ASP.NET 4 generates the following HTML for the control settings shown previously: <span id="Label1" class="aspNetDisabled">Test</span> You can change the value of the class attribute that is rendered by default when a control is disabled by setting the DisabledCssClass property. CSS for Validation Controls In ASP.NET 3.5, validation controls render a default color of red as an inline style. For example, the following markup creates a RequiredFieldValidator control: <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ErrorMessage="Required Field" ControlToValidate="RadioButtonList1" /> ASP.NET 3.5 renders the following HTML for the validator control: <span id="RequiredFieldValidator1" style="color:Red;visibility:hidden;">RequiredFieldValidator</span> By default, ASP.NET 4 does not render an inline style to set the color to red. An inline style is used only to hide or show the validator, as shown in the following example: <span id="RequiredFieldValidator1" style"visibility:hidden;">RequiredFieldValidator</span> Therefore, ASP.NET 4 does not automatically show error messages in red. For information about how to use CSS to specify a visual style for a validation control, see Validating User Input in ASP.NET Web Pages. CSS for the Hidden Fields Div Element ASP.NET uses hidden fields to store state information such as view state and control state. These hidden fields are contained by a div element. In ASP.NET 3.5, this div element does not have a class attribute or an id attribute. Therefore, CSS rules that affect all div elements could unintentionally cause this div to be visible. To avoid this problem, ASP.NET 4 renders the div element for hidden fields with a CSS class that you can use to differentiate the hidden fields div from others. The new classvalue is shown in the following example: <div class="aspNetHidden"> CSS for the Table, Image, and ImageButton Controls By default, in ASP.NET 3.5, some controls set the border attribute of rendered HTML to zero (0). The following example shows HTML that is generated by the Table control in ASP.NET 3.5: <table id="Table2" border="0"> The Image control and the ImageButton control also do this. Because this is not necessary and provides visual formatting information that should be provided by using CSS, the attribute is not generated in ASP.NET 4. CSS for the UpdatePanel and UpdateProgress Controls In ASP.NET 3.5, the UpdatePanel and UpdateProgress controls do not support expando attributes. This makes it impossible to set a CSS class on the HTMLelements that they render. In ASP.NET 4 these controls have been changed to accept expando attributes, as shown in the following example: <asp:UpdatePanel runat="server" class="myStyle"> </asp:UpdatePanel> The following HTML is rendered for this markup: <div id="ctl00_MainContent_UpdatePanel1" class="expandoclass"> </div> Eliminating Unnecessary Outer Tables In ASP.NET 3.5, the HTML that is rendered for the following controls is wrapped in a table element whose purpose is to apply inline styles to the entire control: FormView Login PasswordRecovery ChangePassword If you use templates to customize the appearance of these controls, you can specify CSS styles in the markup that you provide in the templates. In that case, no extra outer table is required. In ASP.NET 4, you can prevent the table from being rendered by setting the new RenderOuterTable property to false. Layout Templates for Wizard Controls In ASP.NET 3.5, the Wizard and CreateUserWizard controls generate an HTML table element that is used for visual formatting. In ASP.NET 4 you can use a LayoutTemplate element to specify the layout. If you do this, the HTML table element is not generated. In the template, you create placeholder controls to indicate where items should be dynamically inserted into the control. (This is similar to how the template model for the ListView control works.) For more information, see the Wizard.LayoutTemplate property. New HTML Formatting Options for the CheckBoxList and RadioButtonList Controls ASP.NET 3.5 uses HTML table elements to format the output for the CheckBoxList and RadioButtonList controls. To provide an alternative that does not use tables for visual formatting, ASP.NET 4 adds two new options to the RepeatLayout enumeration: UnorderedList. This option causes the HTML output to be formatted by using ul and li elements instead of a table. OrderedList. This option causes the HTML output to be formatted by using ol and li elements instead of a table. For examples of HTML that is rendered for the new options, see the RepeatLayout enumeration. Header and Footer Elements for the Table Control In ASP.NET 3.5, the Table control can be configured to render thead and tfoot elements by setting the TableSection property of the TableHeaderRow class and the TableFooterRow class. In ASP.NET 4 these properties are set to the appropriate values by default. CSS and ARIA Support for the Menu Control In ASP.NET 3.5, the Menu control uses HTML table elements for visual formatting, and in some configurations it is not keyboard-accessible. ASP.NET 4 addresses these problems and improves accessibility in the following ways: The generated HTML is structured as an unordered list (ul and li elements). CSS is used for visual formatting. The menu behaves in accordance with ARIA standards for keyboard access. You can use arrow keys to navigate menu items. (For information about ARIA, see Accessibility in Visual Studio and ASP.NET.) ARIA role and property attributes are added to the generated HTML. (Attributes are added by using JavaScript instead of included in the HTML, to avoid generating HTML that would cause markup validation errors.) Styles for the Menu control are rendered in a style block at the top of the page, instead of inline with the rendered HTML elements. If you want to use a separate CSS file so that you can modify the menu styles, you can set the Menu control's new IncludeStyleBlock property to false, in which case the style block is not generated. Valid XHTML for the HtmlForm Control In ASP.NET 3.5, the HtmlForm control (which is created implicitly by the <form runat="server"> tag) renders an HTML form element that has both name and id attributes. The name attribute is deprecated in XHTML 1.1. Therefore, this control does not render the name attribute in ASP.NET 4. Maintaining Backward Compatibility in Control Rendering An existing ASP.NET Web site might have code in it that assumes that controls are rendering HTML the way they do in ASP.NET 3.5. To avoid causing backward compatibility problems when you upgrade the site to ASP.NET 4, you can have ASP.NET continue to generate HTML the way it does in ASP.NET 3.5 after you upgrade the site. To do so, you can set the controlRenderingCompatibilityVersion attribute of the pages element to "3.5" in the Web.config file of an ASP.NET 4 Web site, as shown in the following example: <system.web> <pages controlRenderingCompatibilityVersion="3.5"/> </system.web> If this setting is omitted, the default value is the same as the version of ASP.NET that the Web site targets. (For information about multi-targeting in ASP.NET, see .NET Framework Multi-Targeting for ASP.NET Web Projects.) ASP.NET MVC ASP.NET MVC helps Web developers build compelling standards-based Web sites that are easy to maintain because it decreases the dependency among application layers by using the Model-View-Controller (MVC) pattern. MVC provides complete control over the page markup. It also improves testability by inherently supporting Test Driven Development (TDD). Web sites created using ASP.NET MVC have a modular architecture. This allows members of a team to work independently on the various modules and can be used to improve collaboration. For example, developers can work on the model and controller layers (data and logic), while the designer work on the view (presentation). For tutorials, walkthroughs, conceptual content, code samples, and a complete API reference, see ASP.NET MVC 2. Dynamic Data Dynamic Data was introduced in the .NET Framework 3.5 SP1 release in mid-2008. This feature provides many enhancements for creating data-driven applications, such as the following: A RAD experience for quickly building a data-driven Web site. Automatic validation that is based on constraints defined in the data model. The ability to easily change the markup that is generated for fields in the GridView and DetailsView controls by using field templates that are part of your Dynamic Data project. For ASP.NET 4, Dynamic Data has been enhanced to give developers even more power for quickly building data-driven Web sites. For more information, see ASP.NET Dynamic Data Content Map. Enabling Dynamic Data for Individual Data-Bound Controls in Existing Web Applications You can use Dynamic Data features in existing ASP.NET Web applications that do not use scaffolding by enabling Dynamic Data for individual data-bound controls. Dynamic Data provides the presentation and data layer support for rendering these controls. When you enable Dynamic Data for data-bound controls, you get the following benefits: Setting default values for data fields. Dynamic Data enables you to provide default values at run time for fields in a data control. Interacting with the database without creating and registering a data model. Automatically validating the data that is entered by the user without writing any code. For more information, see Walkthrough: Enabling Dynamic Data in ASP.NET Data-Bound Controls. New Field Templates for URLs and E-mail Addresses ASP.NET 4 introduces two new built-in field templates, EmailAddress.ascx and Url.ascx. These templates are used for fields that are marked as EmailAddress or Url using the DataTypeAttribute attribute. For EmailAddress objects, the field is displayed as a hyperlink that is created by using the mailto: protocol. When users click the link, it opens the user's e-mail client and creates a skeleton message. Objects typed as Url are displayed as ordinary hyperlinks. The following example shows how to mark fields. [DataType(DataType.EmailAddress)] public object HomeEmail { get; set; } [DataType(DataType.Url)] public object Website { get; set; } Creating Links with the DynamicHyperLink Control Dynamic Data uses the new routing feature that was added in the .NET Framework 3.5 SP1 to control the URLs that users see when they access the Web site. The new DynamicHyperLink control makes it easy to build links to pages in a Dynamic Data site. For information, see How to: Create Table Action Links in Dynamic Data Support for Inheritance in the Data Model Both the ADO.NET Entity Framework and LINQ to SQL support inheritance in their data models. An example of this might be a database that has an InsurancePolicy table. It might also contain CarPolicy and HousePolicy tables that have the same fields as InsurancePolicy and then add more fields. Dynamic Data has been modified to understand inherited objects in the data model and to support scaffolding for the inherited tables. For more information, see Walkthrough: Mapping Table-per-Hierarchy Inheritance in Dynamic Data. Support for Many-to-Many Relationships (Entity Framework Only) The Entity Framework has rich support for many-to-many relationships between tables, which is implemented by exposing the relationship as a collection on an Entity object. New field templates (ManyToMany.ascx and ManyToMany_Edit.ascx) have been added to provide support for displaying and editing data that is involved in many-to-many relationships. For more information, see Working with Many-to-Many Data Relationships in Dynamic Data. New Attributes to Control Display and Support Enumerations The DisplayAttribute has been added to give you additional control over how fields are displayed. The DisplayNameAttribute attribute in earlier versions of Dynamic Data enabled you to change the name that is used as a caption for a field. The new DisplayAttribute class lets you specify more options for displaying a field, such as the order in which a field is displayed and whether a field will be used as a filter. The attribute also provides independent control of the name that is used for the labels in a GridView control, the name that is used in a DetailsView control, the help text for the field, and the watermark used for the field (if the field accepts text input). The EnumDataTypeAttribute class has been added to let you map fields to enumerations. When you apply this attribute to a field, you specify an enumeration type. Dynamic Data uses the new Enumeration.ascx field template to create UI for displaying and editing enumeration values. The template maps the values from the database to the names in the enumeration. Enhanced Support for Filters Dynamic Data 1.0 had built-in filters for Boolean columns and foreign-key columns. The filters did not let you specify the order in which they were displayed. The new DisplayAttribute attribute addresses this by giving you control over whether a column appears as a filter and in what order it will be displayed. An additional enhancement is that filtering support has been rewritten to use the new QueryExtender feature of Web Forms. This lets you create filters without requiring knowledge of the data source control that the filters will be used with. Along with these extensions, filters have also been turned into template controls, which lets you add new ones. Finally, the DisplayAttribute class mentioned earlier allows the default filter to be overridden, in the same way that UIHint allows the default field template for a column to be overridden. For more information, see Walkthrough: Filtering Rows in Tables That Have a Parent-Child Relationship and QueryableFilterRepeater. ASP.NET Chart Control The ASP.NET chart server control enables you to create ASP.NET pages applications that have simple, intuitive charts for complex statistical or financial analysis. The chart control supports the following features: Data series, chart areas, axes, legends, labels, titles, and more. Data binding. Data manipulation, such as copying, splitting, merging, alignment, grouping, sorting, searching, and filtering. Statistical formulas and financial formulas. Advanced chart appearance, such as 3-D, anti-aliasing, lighting, and perspective. Events and customizations. Interactivity and Microsoft Ajax. Support for the Ajax Content Delivery Network (CDN), which provides an optimized way for you to add Microsoft Ajax Library and jQuery scripts to your Web applications. For more information, see Chart Web Server Control Overview. Visual Web Developer Enhancements The following sections provide information about enhancements and new features in Visual Studio 2010 and Visual Web Developer Express. The Web page designer in Visual Studio 2010 has been enhanced for better CSS compatibility, includes additional support for HTML and ASP.NET markup snippets, and features a redesigned version of IntelliSense for JScript. Improved CSS Compatibility The Visual Web Developer designer in Visual Studio 2010 has been updated to improve CSS 2.1 standards compliance. The designer better preserves HTML source code and is more robust than in previous versions of Visual Studio. HTML and JScript Snippets In the HTML editor, IntelliSense auto-completes tag names. The IntelliSense Snippets feature auto-completes whole tags and more. In Visual Studio 2010, IntelliSense snippets are supported for JScript, alongside C# and Visual Basic, which were supported in earlier versions of Visual Studio. Visual Studio 2010 includes over 200 snippets that help you auto-complete common ASP.NET and HTML tags, including required attributes (such as runat="server") and common attributes specific to a tag (such as ID, DataSourceID, ControlToValidate, and Text). You can download additional snippets, or you can write your own snippets that encapsulate the blocks of markup that you or your team use for common tasks. For more information on HTML snippets, see Walkthrough: Using HTML Snippets. JScript IntelliSense Enhancements In Visual 2010, JScript IntelliSense has been redesigned to provide an even richer editing experience. IntelliSense now recognizes objects that have been dynamically generated by methods such as registerNamespace and by similar techniques used by other JavaScript frameworks. Performance has been improved to analyze large libraries of script and to display IntelliSense with little or no processing delay. Compatibility has been significantly increased to support almost all third-party libraries and to support diverse coding styles. Documentation comments are now parsed as you type and are immediately leveraged by IntelliSense. Web Application Deployment with Visual Studio 2010 For Web application projects, Visual Studio now provides tools that work with the IIS Web Deployment Tool (Web Deploy) to automate many processes that had to be done manually in earlier versions of ASP.NET. For example, the following tasks can now be automated: Creating an IIS application on the destination computer and configuring IIS settings. Copying files to the destination computer. Changing Web.config settings that must be different in the destination environment. Propagating changes to data or data structures in SQL Server databases that are used by the Web application. For more information about Web application deployment, see ASP.NET Deployment Content Map. Enhancements to ASP.NET Multi-Targeting ASP.NET 4 adds new features to the multi-targeting feature to make it easier to work with projects that target earlier versions of the .NET Framework. Multi-targeting was introduced in ASP.NET 3.5 to enable you to use the latest version of Visual Studio without having to upgrade existing Web sites or Web services to the latest version of the .NET Framework. In Visual Studio 2008, when you work with a project targeted for an earlier version of the .NET Framework, most features of the development environment adapt to the targeted version. However, IntelliSense displays language features that are available in the current version, and property windows display properties available in the current version. In Visual Studio 2010, only language features and properties available in the targeted version of the .NET Framework are shown. For more information about multi-targeting, see the following topics: .NET Framework Multi-Targeting for ASP.NET Web Projects ASP.NET Side-by-Side Execution Overview How to: Host Web Applications That Use Different Versions of the .NET Framework on the Same Server How to: Deploy Web Site Projects Targeted for Earlier Versions of the .NET Framework

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An Introduction to ASP.NET Web API

- by Rick Strahl

Microsoft recently released ASP.NET MVC 4.0 and .NET 4.5 and along with it, the brand spanking new ASP.NET Web API. Web API is an exciting new addition to the ASP.NET stack that provides a new, well-designed HTTP framework for creating REST and AJAX APIs (API is Microsoft’s new jargon for a service, in case you’re wondering). Although Web API ships and installs with ASP.NET MVC 4, you can use Web API functionality in any ASP.NET project, including WebForms, WebPages and MVC or just a Web API by itself. And you can also self-host Web API in your own applications from Console, Desktop or Service applications. If you're interested in a high level overview on what ASP.NET Web API is and how it fits into the ASP.NET stack you can check out my previous post: Where does ASP.NET Web API fit? In the following article, I'll focus on a practical, by example introduction to ASP.NET Web API. All the code discussed in this article is available in GitHub: https://github.com/RickStrahl/AspNetWebApiArticle [republished from my Code Magazine Article and updated for RTM release of ASP.NET Web API] Getting Started To start I’ll create a new empty ASP.NET application to demonstrate that Web API can work with any kind of ASP.NET project. Although you can create a new project based on the ASP.NET MVC/Web API template to quickly get up and running, I’ll take you through the manual setup process, because one common use case is to add Web API functionality to an existing ASP.NET application. This process describes the steps needed to hook up Web API to any ASP.NET 4.0 application. Start by creating an ASP.NET Empty Project. Then create a new folder in the project called Controllers. Add a Web API Controller Class Once you have any kind of ASP.NET project open, you can add a Web API Controller class to it. Web API Controllers are very similar to MVC Controller classes, but they work in any kind of project. Add a new item to this folder by using the Add New Item option in Visual Studio and choose Web API Controller Class, as shown in Figure 1. Figure 1: This is how you create a new Controller Class in Visual Studio Make sure that the name of the controller class includes Controller at the end of it, which is required in order for Web API routing to find it. Here, the name for the class is AlbumApiController. For this example, I’ll use a Music Album model to demonstrate basic behavior of Web API. The model consists of albums and related songs where an album has properties like Name, Artist and YearReleased and a list of songs with a SongName and SongLength as well as an AlbumId that links it to the album. You can find the code for the model (and the rest of these samples) on Github. To add the file manually, create a new folder called Model, and add a new class Album.cs and copy the code into it. There’s a static AlbumData class with a static CreateSampleAlbumData() method that creates a short list of albums on a static .Current that I’ll use for the examples. Before we look at what goes into the controller class though, let’s hook up routing so we can access this new controller. Hooking up Routing in Global.asax To start, I need to perform the one required configuration task in order for Web API to work: I need to configure routing to the controller. Like MVC, Web API uses routing to provide clean, extension-less URLs to controller methods. Using an extension method to ASP.NET’s static RouteTable class, you can use the MapHttpRoute() (in the System.Web.Http namespace) method to hook-up the routing during Application_Start in global.asax.cs shown in Listing 1.using System; using System.Web.Routing; using System.Web.Http; namespace AspNetWebApi { public class Global : System.Web.HttpApplication { protected void Application_Start(object sender, EventArgs e) { RouteTable.Routes.MapHttpRoute( name: "AlbumVerbs", routeTemplate: "albums/{title}", defaults: new { symbol = RouteParameter.Optional, controller="AlbumApi" } ); } } } This route configures Web API to direct URLs that start with an albums folder to the AlbumApiController class. Routing in ASP.NET is used to create extensionless URLs and allows you to map segments of the URL to specific Route Value parameters. A route parameter, with a name inside curly brackets like {name}, is mapped to parameters on the controller methods. Route parameters can be optional, and there are two special route parameters – controller and action – that determine the controller to call and the method to activate respectively. HTTP Verb Routing Routing in Web API can route requests by HTTP Verb in addition to standard {controller},{action} routing. For the first examples, I use HTTP Verb routing, as shown Listing 1. Notice that the route I’ve defined does not include an {action} route value or action value in the defaults. Rather, Web API can use the HTTP Verb in this route to determine the method to call the controller, and a GET request maps to any method that starts with Get. So methods called Get() or GetAlbums() are matched by a GET request and a POST request maps to a Post() or PostAlbum(). Web API matches a method by name and parameter signature to match a route, query string or POST values. In lieu of the method name, the [HttpGet,HttpPost,HttpPut,HttpDelete, etc] attributes can also be used to designate the accepted verbs explicitly if you don’t want to follow the verb naming conventions. Although HTTP Verb routing is a good practice for REST style resource APIs, it’s not required and you can still use more traditional routes with an explicit {action} route parameter. When {action} is supplied, the HTTP verb routing is ignored. I’ll talk more about alternate routes later. When you’re finished with initial creation of files, your project should look like Figure 2. Figure 2: The initial project has the new API Controller Album model Creating a small Album Model Now it’s time to create some controller methods to serve data. For these examples, I’ll use a very simple Album and Songs model to play with, as shown in Listing 2. public class Song { public string AlbumId { get; set; } [Required, StringLength(80)] public string SongName { get; set; } [StringLength(5)] public string SongLength { get; set; } } public class Album { public string Id { get; set; } [Required, StringLength(80)] public string AlbumName { get; set; } [StringLength(80)] public string Artist { get; set; } public int YearReleased { get; set; } public DateTime Entered { get; set; } [StringLength(150)] public string AlbumImageUrl { get; set; } [StringLength(200)] public string AmazonUrl { get; set; } public virtual List<Song> Songs { get; set; } public Album() { Songs = new List<Song>(); Entered = DateTime.Now; // Poor man's unique Id off GUID hash Id = Guid.NewGuid().GetHashCode().ToString("x"); } public void AddSong(string songName, string songLength = null) { this.Songs.Add(new Song() { AlbumId = this.Id, SongName = songName, SongLength = songLength }); } } Once the model has been created, I also added an AlbumData class that generates some static data in memory that is loaded onto a static .Current member. The signature of this class looks like this and that's what I'll access to retrieve the base data:public static class AlbumData { // sample data - static list public static List<Album> Current = CreateSampleAlbumData(); /// <summary> /// Create some sample data /// </summary> /// <returns></returns> public static List<Album> CreateSampleAlbumData() { … }} You can check out the full code for the data generation online. Creating an AlbumApiController Web API shares many concepts of ASP.NET MVC, and the implementation of your API logic is done by implementing a subclass of the System.Web.Http.ApiController class. Each public method in the implemented controller is a potential endpoint for the HTTP API, as long as a matching route can be found to invoke it. The class name you create should end in Controller, which is how Web API matches the controller route value to figure out which class to invoke. Inside the controller you can implement methods that take standard .NET input parameters and return .NET values as results. Web API’s binding tries to match POST data, route values, form values or query string values to your parameters. Because the controller is configured for HTTP Verb based routing (no {action} parameter in the route), any methods that start with Getxxxx() are called by an HTTP GET operation. You can have multiple methods that match each HTTP Verb as long as the parameter signatures are different and can be matched by Web API. In Listing 3, I create an AlbumApiController with two methods to retrieve a list of albums and a single album by its title .public class AlbumApiController : ApiController { public IEnumerable<Album> GetAlbums() { var albums = AlbumData.Current.OrderBy(alb => alb.Artist); return albums; } public Album GetAlbum(string title) { var album = AlbumData.Current .SingleOrDefault(alb => alb.AlbumName.Contains(title)); return album; }} To access the first two requests, you can use the following URLs in your browser: http://localhost/aspnetWebApi/albumshttp://localhost/aspnetWebApi/albums/Dirty%20Deeds Note that you’re not specifying the actions of GetAlbum or GetAlbums in these URLs. Instead Web API’s routing uses HTTP GET verb to route to these methods that start with Getxxx() with the first mapping to the parameterless GetAlbums() method and the latter to the GetAlbum(title) method that receives the title parameter mapped as optional in the route. Content Negotiation When you access any of the URLs above from a browser, you get either an XML or JSON result returned back. The album list result for Chrome 17 and Internet Explorer 9 is shown Figure 3. Figure 3: Web API responses can vary depending on the browser used, demonstrating Content Negotiation in action as these two browsers send different HTTP Accept headers. Notice that the results are not the same: Chrome returns an XML response and IE9 returns a JSON response. Whoa, what’s going on here? Shouldn’t we see the same result in both browsers? Actually, no. Web API determines what type of content to return based on Accept headers. HTTP clients, like browsers, use Accept headers to specify what kind of content they’d like to see returned. Browsers generally ask for HTML first, followed by a few additional content types. Chrome (and most other major browsers) ask for: Accept: text/html, application/xhtml+xml,application/xml; q=0.9,*/*;q=0.8 IE9 asks for: Accept: text/html, application/xhtml+xml, */* Note that Chrome’s Accept header includes application/xml, which Web API finds in its list of supported media types and returns an XML response. IE9 does not include an Accept header type that works on Web API by default, and so it returns the default format, which is JSON. This is an important and very useful feature that was missing from any previous Microsoft REST tools: Web API automatically switches output formats based on HTTP Accept headers. Nowhere in the server code above do you have to explicitly specify the output format. Rather, Web API determines what format the client is requesting based on the Accept headers and automatically returns the result based on the available formatters. This means that a single method can handle both XML and JSON results.. Using this simple approach makes it very easy to create a single controller method that can return JSON, XML, ATOM or even OData feeds by providing the appropriate Accept header from the client. By default you don’t have to worry about the output format in your code. Note that you can still specify an explicit output format if you choose, either globally by overriding the installed formatters, or individually by returning a lower level HttpResponseMessage instance and setting the formatter explicitly. More on that in a minute. Along the same lines, any content sent to the server via POST/PUT is parsed by Web API based on the HTTP Content-type of the data sent. The same formats allowed for output are also allowed on input. Again, you don’t have to do anything in your code – Web API automatically performs the deserialization from the content. Accessing Web API JSON Data with jQuery A very common scenario for Web API endpoints is to retrieve data for AJAX calls from the Web browser. Because JSON is the default format for Web API, it’s easy to access data from the server using jQuery and its getJSON() method. This example receives the albums array from GetAlbums() and databinds it into the page using knockout.js.$.getJSON("albums/", function (albums) { // make knockout template visible $(".album").show(); // create view object and attach array var view = { albums: albums }; ko.applyBindings(view); }); Figure 4 shows this and the next example’s HTML output. You can check out the complete HTML and script code at http://goo.gl/Ix33C (.html) and http://goo.gl/tETlg (.js). Figu Figure 4: The Album Display sample uses JSON data loaded from Web API. The result from the getJSON() call is a JavaScript object of the server result, which comes back as a JavaScript array. In the code, I use knockout.js to bind this array into the UI, which as you can see, requires very little code, instead using knockout’s data-bind attributes to bind server data to the UI. Of course, this is just one way to use the data – it’s entirely up to you to decide what to do with the data in your client code. Along the same lines, I can retrieve a single album to display when the user clicks on an album. The response returns the album information and a child array with all the songs. The code to do this is very similar to the last example where we pulled the albums array:$(".albumlink").live("click", function () { var id = $(this).data("id"); // title $.getJSON("albums/" + id, function (album) { ko.applyBindings(album, $("#divAlbumDialog")[0]); $("#divAlbumDialog").show(); }); }); Here the URL looks like this: /albums/Dirty%20Deeds, where the title is the ID captured from the clicked element’s data ID attribute. Explicitly Overriding Output Format When Web API automatically converts output using content negotiation, it does so by matching Accept header media types to the GlobalConfiguration.Configuration.Formatters and the SupportedMediaTypes of each individual formatter. You can add and remove formatters to globally affect what formats are available and it’s easy to create and plug in custom formatters.The example project includes a JSONP formatter that can be plugged in to provide JSONP support for requests that have a callback= querystring parameter. Adding, removing or replacing formatters is a global option you can use to manipulate content. It’s beyond the scope of this introduction to show how it works, but you can review the sample code or check out my blog entry on the subject (http://goo.gl/UAzaR). If automatic processing is not desirable in a particular Controller method, you can override the response output explicitly by returning an HttpResponseMessage instance. HttpResponseMessage is similar to ActionResult in ASP.NET MVC in that it’s a common way to return an abstract result message that contains content. HttpResponseMessage s parsed by the Web API framework using standard interfaces to retrieve the response data, status code, headers and so on[MS2] . Web API turns every response – including those Controller methods that return static results – into HttpResponseMessage instances. Explicitly returning an HttpResponseMessage instance gives you full control over the output and lets you mostly bypass WebAPI’s post-processing of the HTTP response on your behalf. HttpResponseMessage allows you to customize the response in great detail. Web API’s attention to detail in the HTTP spec really shows; many HTTP options are exposed as properties and enumerations with detailed IntelliSense comments. Even if you’re new to building REST-based interfaces, the API guides you in the right direction for returning valid responses and response codes. For example, assume that I always want to return JSON from the GetAlbums() controller method and ignore the default media type content negotiation. To do this, I can adjust the output format and headers as shown in Listing 4.public HttpResponseMessage GetAlbums() { var albums = AlbumData.Current.OrderBy(alb => alb.Artist); // Create a new HttpResponse with Json Formatter explicitly var resp = new HttpResponseMessage(HttpStatusCode.OK); resp.Content = new ObjectContent<IEnumerable<Album>>( albums, new JsonMediaTypeFormatter()); // Get Default Formatter based on Content Negotiation //var resp = Request.CreateResponse<IEnumerable<Album>>(HttpStatusCode.OK, albums); resp.Headers.ConnectionClose = true; resp.Headers.CacheControl = new CacheControlHeaderValue(); resp.Headers.CacheControl.Public = true; return resp; } This example returns the same IEnumerable<Album> value, but it wraps the response into an HttpResponseMessage so you can control the entire HTTP message result including the headers, formatter and status code. In Listing 4, I explicitly specify the formatter using the JsonMediaTypeFormatter to always force the content to JSON. If you prefer to use the default content negotiation with HttpResponseMessage results, you can create the Response instance using the Request.CreateResponse method:var resp = Request.CreateResponse<IEnumerable<Album>>(HttpStatusCode.OK, albums); This provides you an HttpResponse object that's pre-configured with the default formatter based on Content Negotiation. Once you have an HttpResponse object you can easily control most HTTP aspects on this object. What's sweet here is that there are many more detailed properties on HttpResponse than the core ASP.NET Response object, with most options being explicitly configurable with enumerations that make it easy to pick the right headers and response codes from a list of valid codes. It makes HTTP features available much more discoverable even for non-hardcore REST/HTTP geeks. Non-Serialized Results The output returned doesn’t have to be a serialized value but can also be raw data, like strings, binary data or streams. You can use the HttpResponseMessage.Content object to set a number of common Content classes. Listing 5 shows how to return a binary image using the ByteArrayContent class from a Controller method. [HttpGet] public HttpResponseMessage AlbumArt(string title) { var album = AlbumData.Current.FirstOrDefault(abl => abl.AlbumName.StartsWith(title)); if (album == null) { var resp = Request.CreateResponse<ApiMessageError>( HttpStatusCode.NotFound, new ApiMessageError("Album not found")); return resp; } // kinda silly - we would normally serve this directly // but hey - it's a demo. var http = new WebClient(); var imageData = http.DownloadData(album.AlbumImageUrl); // create response and return var result = new HttpResponseMessage(HttpStatusCode.OK); result.Content = new ByteArrayContent(imageData); result.Content.Headers.ContentType = new MediaTypeHeaderValue("image/jpeg"); return result; } The image retrieval from Amazon is contrived, but it shows how to return binary data using ByteArrayContent. It also demonstrates that you can easily return multiple types of content from a single controller method, which is actually quite common. If an error occurs - such as a resource can’t be found or a validation error – you can return an error response to the client that’s very specific to the error. In GetAlbumArt(), if the album can’t be found, we want to return a 404 Not Found status (and realistically no error, as it’s an image). Note that if you are not using HTTP Verb-based routing or not accessing a method that starts with Get/Post etc., you have to specify one or more HTTP Verb attributes on the method explicitly. Here, I used the [HttpGet] attribute to serve the image. Another option to handle the error could be to return a fixed placeholder image if no album could be matched or the album doesn’t have an image. When returning an error code, you can also return a strongly typed response to the client. For example, you can set the 404 status code and also return a custom error object (ApiMessageError is a class I defined) like this:return Request.CreateResponse<ApiMessageError>( HttpStatusCode.NotFound, new ApiMessageError("Album not found") ); If the album can be found, the image will be returned. The image is downloaded into a byte[] array, and then assigned to the result’s Content property. I created a new ByteArrayContent instance and assigned the image’s bytes and the content type so that it displays properly in the browser. There are other content classes available: StringContent, StreamContent, ByteArrayContent, MultipartContent, and ObjectContent are at your disposal to return just about any kind of content. You can create your own Content classes if you frequently return custom types and handle the default formatter assignments that should be used to send the data out . Although HttpResponseMessage results require more code than returning a plain .NET value from a method, it allows much more control over the actual HTTP processing than automatic processing. It also makes it much easier to test your controller methods as you get a response object that you can check for specific status codes and output messages rather than just a result value. Routing Again Ok, let’s get back to the image example. Using the original routing we have setup using HTTP Verb routing there's no good way to serve the image. In order to return my album art image I’d like to use a URL like this: http://localhost/aspnetWebApi/albums/Dirty%20Deeds/image In order to create a URL like this, I have to create a new Controller because my earlier routes pointed to the AlbumApiController using HTTP Verb routing. HTTP Verb based routing is great for representing a single set of resources such as albums. You can map operations like add, delete, update and read easily using HTTP Verbs. But you cannot mix action based routing into a an HTTP Verb routing controller - you can only map HTTP Verbs and each method has to be unique based on parameter signature. You can't have multiple GET operations to methods with the same signature. So GetImage(string id) and GetAlbum(string title) are in conflict in an HTTP GET routing scenario. In fact, I was unable to make the above Image URL work with any combination of HTTP Verb plus Custom routing using the single Albums controller. There are number of ways around this, but all involve additional controllers. Personally, I think it’s easier to use explicit Action routing and then add custom routes if you need to simplify your URLs further. So in order to accommodate some of the other examples, I created another controller – AlbumRpcApiController – to handle all requests that are explicitly routed via actions (/albums/rpc/AlbumArt) or are custom routed with explicit routes defined in the HttpConfiguration. I added the AlbumArt() method to this new AlbumRpcApiController class. For the image URL to work with the new AlbumRpcApiController, you need a custom route placed before the default route from Listing 1.RouteTable.Routes.MapHttpRoute( name: "AlbumRpcApiAction", routeTemplate: "albums/rpc/{action}/{title}", defaults: new { title = RouteParameter.Optional, controller = "AlbumRpcApi", action = "GetAblums" } ); Now I can use either of the following URLs to access the image: Custom route: (/albums/rpc/{title}/image)http://localhost/aspnetWebApi/albums/PowerAge/image Action route: (/albums/rpc/action/{title})http://localhost/aspnetWebAPI/albums/rpc/albumart/PowerAge Sending Data to the Server To send data to the server and add a new album, you can use an HTTP POST operation. Since I’m using HTTP Verb-based routing in the original AlbumApiController, I can implement a method called PostAlbum()to accept a new album from the client. Listing 6 shows the Web API code to add a new album.public HttpResponseMessage PostAlbum(Album album) { if (!this.ModelState.IsValid) { // my custom error class var error = new ApiMessageError() { message = "Model is invalid" }; // add errors into our client error model for client foreach (var prop in ModelState.Values) { var modelError = prop.Errors.FirstOrDefault(); if (!string.IsNullOrEmpty(modelError.ErrorMessage)) error.errors.Add(modelError.ErrorMessage); else error.errors.Add(modelError.Exception.Message); } return Request.CreateResponse<ApiMessageError>(HttpStatusCode.Conflict, error); } // update song id which isn't provided foreach (var song in album.Songs) song.AlbumId = album.Id; // see if album exists already var matchedAlbum = AlbumData.Current .SingleOrDefault(alb => alb.Id == album.Id || alb.AlbumName == album.AlbumName); if (matchedAlbum == null) AlbumData.Current.Add(album); else matchedAlbum = album; // return a string to show that the value got here var resp = Request.CreateResponse(HttpStatusCode.OK, string.Empty); resp.Content = new StringContent(album.AlbumName + " " + album.Entered.ToString(), Encoding.UTF8, "text/plain"); return resp; } The PostAlbum() method receives an album parameter, which is automatically deserialized from the POST buffer the client sent. The data passed from the client can be either XML or JSON. Web API automatically figures out what format it needs to deserialize based on the content type and binds the content to the album object. Web API uses model binding to bind the request content to the parameter(s) of controller methods. Like MVC you can check the model by looking at ModelState.IsValid. If it’s not valid, you can run through the ModelState.Values collection and check each binding for errors. Here I collect the error messages into a string array that gets passed back to the client via the result ApiErrorMessage object. When a binding error occurs, you’ll want to return an HTTP error response and it’s best to do that with an HttpResponseMessage result. In Listing 6, I used a custom error class that holds a message and an array of detailed error messages for each binding error. I used this object as the content to return to the client along with my Conflict HTTP Status Code response. If binding succeeds, the example returns a string with the name and date entered to demonstrate that you captured the data. Normally, a method like this should return a Boolean or no response at all (HttpStatusCode.NoConent). The sample uses a simple static list to hold albums, so once you’ve added the album using the Post operation, you can hit the /albums/ URL to see that the new album was added. The client jQuery code to call the POST operation from the client with jQuery is shown in Listing 7. var id = new Date().getTime().toString(); var album = { "Id": id, "AlbumName": "Power Age", "Artist": "AC/DC", "YearReleased": 1977, "Entered": "2002-03-11T18:24:43.5580794-10:00", "AlbumImageUrl": http://ecx.images-amazon.com/images/…, "AmazonUrl": http://www.amazon.com/…, "Songs": [ { "SongName": "Rock 'n Roll Damnation", "SongLength": 3.12}, { "SongName": "Downpayment Blues", "SongLength": 4.22 }, { "SongName": "Riff Raff", "SongLength": 2.42 } ] } $.ajax( { url: "albums/", type: "POST", contentType: "application/json", data: JSON.stringify(album), processData: false, beforeSend: function (xhr) { // not required since JSON is default output xhr.setRequestHeader("Accept", "application/json"); }, success: function (result) { // reload list of albums page.loadAlbums(); }, error: function (xhr, status, p3, p4) { var err = "Error"; if (xhr.responseText && xhr.responseText[0] == "{") err = JSON.parse(xhr.responseText).message; alert(err); } }); The code in Listing 7 creates an album object in JavaScript to match the structure of the .NET Album class. This object is passed to the $.ajax() function to send to the server as POST. The data is turned into JSON and the content type set to application/json so that the server knows what to convert when deserializing in the Album instance. The jQuery code hooks up success and failure events. Success returns the result data, which is a string that’s echoed back with an alert box. If an error occurs, jQuery returns the XHR instance and status code. You can check the XHR to see if a JSON object is embedded and if it is, you can extract it by de-serializing it and accessing the .message property. REST standards suggest that updates to existing resources should use PUT operations. REST standards aside, I’m not a big fan of separating out inserts and updates so I tend to have a single method that handles both. But if you want to follow REST suggestions, you can create a PUT method that handles updates by forwarding the PUT operation to the POST method:public HttpResponseMessage PutAlbum(Album album) { return PostAlbum(album); } To make the corresponding $.ajax() call, all you have to change from Listing 7 is the type: from POST to PUT. Model Binding with UrlEncoded POST Variables In the example in Listing 7 I used JSON objects to post a serialized object to a server method that accepted an strongly typed object with the same structure, which is a common way to send data to the server. However, Web API supports a number of different ways that data can be received by server methods. For example, another common way is to use plain UrlEncoded POST values to send to the server. Web API supports Model Binding that works similar (but not the same) as MVC's model binding where POST variables are mapped to properties of object parameters of the target method. This is actually quite common for AJAX calls that want to avoid serialization and the potential requirement of a JSON parser on older browsers. For example, using jQUery you might use the $.post() method to send a new album to the server (albeit one without songs) using code like the following:$.post("albums/",{AlbumName: "Dirty Deeds", YearReleased: 1976 … },albumPostCallback); Although the code looks very similar to the client code we used before passing JSON, here the data passed is URL encoded values (AlbumName=Dirty+Deeds&YearReleased=1976 etc.). Web API then takes this POST data and maps each of the POST values to the properties of the Album object in the method's parameter. Although the client code is different the server can both handle the JSON object, or the UrlEncoded POST values. Dynamic Access to POST Data There are also a few options available to dynamically access POST data, if you know what type of data you're dealing with. If you have POST UrlEncoded values, you can dynamically using a FormsDataCollection:[HttpPost] public string PostAlbum(FormDataCollection form) { return string.Format("{0} - released {1}", form.Get("AlbumName"),form.Get("RearReleased")); } The FormDataCollection is a very simple object, that essentially provides the same functionality as Request.Form[] in ASP.NET. Request.Form[] still works if you're running hosted in an ASP.NET application. However as a general rule, while ASP.NET's functionality is always available when running Web API hosted inside of an ASP.NET application, using the built in classes specific to Web API makes it possible to run Web API applications in a self hosted environment outside of ASP.NET. If your client is sending JSON to your server, and you don't want to map the JSON to a strongly typed object because you only want to retrieve a few simple values, you can also accept a JObject parameter in your API methods:[HttpPost] public string PostAlbum(JObject jsonData) { dynamic json = jsonData; JObject jalbum = json.Album; JObject juser = json.User; string token = json.UserToken; var album = jalbum.ToObject<Album>(); var user = juser.ToObject<User>(); return String.Format("{0} {1} {2}", album.AlbumName, user.Name, token); } There quite a few options available to you to receive data with Web API, which gives you more choices for the right tool for the job. Unfortunately one shortcoming of Web API is that POST data is always mapped to a single parameter. This means you can't pass multiple POST parameters to methods that receive POST data. It's possible to accept multiple parameters, but only one can map to the POST content - the others have to come from the query string or route values. I have a couple of Blog POSTs that explain what works and what doesn't here: Passing multiple POST parameters to Web API Controller Methods Mapping UrlEncoded POST Values in ASP.NET Web API Handling Delete Operations Finally, to round out the server API code of the album example we've been discussin, here’s the DELETE verb controller method that allows removal of an album by its title:public HttpResponseMessage DeleteAlbum(string title) { var matchedAlbum = AlbumData.Current.Where(alb => alb.AlbumName == title) .SingleOrDefault(); if (matchedAlbum == null) return new HttpResponseMessage(HttpStatusCode.NotFound); AlbumData.Current.Remove(matchedAlbum); return new HttpResponseMessage(HttpStatusCode.NoContent); } To call this action method using jQuery, you can use:$(".removeimage").live("click", function () { var $el = $(this).parent(".album"); var txt = $el.find("a").text(); $.ajax({ url: "albums/" + encodeURIComponent(txt), type: "Delete", success: function (result) { $el.fadeOut().remove(); }, error: jqError }); } Note the use of the DELETE verb in the $.ajax() call, which routes to DeleteAlbum on the server. DELETE is a non-content operation, so you supply a resource ID (the title) via route value or the querystring. Routing Conflicts In all requests with the exception of the AlbumArt image example shown so far, I used HTTP Verb routing that I set up in Listing 1. HTTP Verb Routing is a recommendation that is in line with typical REST access to HTTP resources. However, it takes quite a bit of effort to create REST-compliant API implementations based only on HTTP Verb routing only. You saw one example that didn’t really fit – the return of an image where I created a custom route albums/{title}/image that required creation of a second controller and a custom route to work. HTTP Verb routing to a controller does not mix with custom or action routing to the same controller because of the limited mapping of HTTP verbs imposed by HTTP Verb routing. To understand some of the problems with verb routing, let’s look at another example. Let’s say you create a GetSortableAlbums() method like this and add it to the original AlbumApiController accessed via HTTP Verb routing:[HttpGet] public IQueryable<Album> SortableAlbums() { var albums = AlbumData.Current; // generally should be done only on actual queryable results (EF etc.) // Done here because we're running with a static list but otherwise might be slow return albums.AsQueryable(); } If you compile this code and try to now access the /albums/ link, you get an error: Multiple Actions were found that match the request. HTTP Verb routing only allows access to one GET operation per parameter/route value match. If more than one method exists with the same parameter signature, it doesn’t work. As I mentioned earlier for the image display, the only solution to get this method to work is to throw it into another controller. Because I already set up the AlbumRpcApiController I can add the method there. First, I should rename the method to SortableAlbums() so I’m not using a Get prefix for the method. This also makes the action parameter look cleaner in the URL - it looks less like a method and more like a noun. I can then create a new route that handles direct-action mapping:RouteTable.Routes.MapHttpRoute( name: "AlbumRpcApiAction", routeTemplate: "albums/rpc/{action}/{title}", defaults: new { title = RouteParameter.Optional, controller = "AlbumRpcApi", action = "GetAblums" } ); As I am explicitly adding a route segment – rpc – into the route template, I can now reference explicit methods in the Web API controller using URLs like this: http://localhost/AspNetWebApi/rpc/SortableAlbums Error Handling I’ve already done some minimal error handling in the examples. For example in Listing 6, I detected some known-error scenarios like model validation failing or a resource not being found and returning an appropriate HttpResponseMessage result. But what happens if your code just blows up or causes an exception? If you have a controller method, like this:[HttpGet] public void ThrowException() { throw new UnauthorizedAccessException("Unauthorized Access Sucka"); } You can call it with this: http://localhost/AspNetWebApi/albums/rpc/ThrowException The default exception handling displays a 500-status response with the serialized exception on the local computer only. When you connect from a remote computer, Web API throws back a 500 HTTP Error with no data returned (IIS then adds its HTML error page). The behavior is configurable in the GlobalConfiguration:GlobalConfiguration .Configuration .IncludeErrorDetailPolicy = IncludeErrorDetailPolicy.Never; If you want more control over your error responses sent from code, you can throw explicit error responses yourself using HttpResponseException. When you throw an HttpResponseException the response parameter is used to generate the output for the Controller action. [HttpGet] public void ThrowError() { var resp = Request.CreateResponse<ApiMessageError>( HttpStatusCode.BadRequest, new ApiMessageError("Your code stinks!")); throw new HttpResponseException(resp); } Throwing an HttpResponseException stops the processing of the controller method and immediately returns the response you passed to the exception. Unlike other Exceptions fired inside of WebAPI, HttpResponseException bypasses the Exception Filters installed and instead just outputs the response you provide. In this case, the serialized ApiMessageError result string is returned in the default serialization format – XML or JSON. You can pass any content to HttpResponseMessage, which includes creating your own exception objects and consistently returning error messages to the client. Here’s a small helper method on the controller that you might use to send exception info back to the client consistently:private void ThrowSafeException(string message, HttpStatusCode statusCode = HttpStatusCode.BadRequest) { var errResponse = Request.CreateResponse<ApiMessageError>(statusCode, new ApiMessageError() { message = message }); throw new HttpResponseException(errResponse); } You can then use it to output any captured errors from code:[HttpGet] public void ThrowErrorSafe() { try { List<string> list = null; list.Add("Rick"); } catch (Exception ex) { ThrowSafeException(ex.Message); } } Exception Filters Another more global solution is to create an Exception Filter. Filters in Web API provide the ability to pre- and post-process controller method operations. An exception filter looks at all exceptions fired and then optionally creates an HttpResponseMessage result. Listing 8 shows an example of a basic Exception filter implementation.public class UnhandledExceptionFilter : ExceptionFilterAttribute { public override void OnException(HttpActionExecutedContext context) { HttpStatusCode status = HttpStatusCode.InternalServerError; var exType = context.Exception.GetType(); if (exType == typeof(UnauthorizedAccessException)) status = HttpStatusCode.Unauthorized; else if (exType == typeof(ArgumentException)) status = HttpStatusCode.NotFound; var apiError = new ApiMessageError() { message = context.Exception.Message }; // create a new response and attach our ApiError object // which now gets returned on ANY exception result var errorResponse = context.Request.CreateResponse<ApiMessageError>(status, apiError); context.Response = errorResponse; base.OnException(context); } } Exception Filter Attributes can be assigned to an ApiController class like this:[UnhandledExceptionFilter] public class AlbumRpcApiController : ApiController or you can globally assign it to all controllers by adding it to the HTTP Configuration's Filters collection:GlobalConfiguration.Configuration.Filters.Add(new UnhandledExceptionFilter()); The latter is a great way to get global error trapping so that all errors (short of hard IIS errors and explicit HttpResponseException errors) return a valid error response that includes error information in the form of a known-error object. Using a filter like this allows you to throw an exception as you normally would and have your filter create a response in the appropriate output format that the client expects. For example, an AJAX application can on failure expect to see a JSON error result that corresponds to the real error that occurred rather than a 500 error along with HTML error page that IIS throws up. You can even create some custom exceptions so you can differentiate your own exceptions from unhandled system exceptions - you often don't want to display error information from 'unknown' exceptions as they may contain sensitive system information or info that's not generally useful to users of your application/site. This is just one example of how ASP.NET Web API is configurable and extensible. Exception filters are just one example of how you can plug-in into the Web API request flow to modify output. Many more hooks exist and I’ll take a closer look at extensibility in Part 2 of this article in the future. Summary Web API is a big improvement over previous Microsoft REST and AJAX toolkits. The key features to its usefulness are its ease of use with simple controller based logic, familiar MVC-style routing, low configuration impact, extensibility at all levels and tight attention to exposing and making HTTP semantics easily discoverable and easy to use. Although none of the concepts used in Web API are new or radical, Web API combines the best of previous platforms into a single framework that’s highly functional, easy to work with, and extensible to boot. I think that Microsoft has hit a home run with Web API. Related Resources Where does ASP.NET Web API fit? Sample Source Code on GitHub Passing multiple POST parameters to Web API Controller Methods Mapping UrlEncoded POST Values in ASP.NET Web API Creating a JSONP Formatter for ASP.NET Web API Removing the XML Formatter from ASP.NET Web API Applications© Rick Strahl, West Wind Technologies, 2005-2012Posted in Web Api Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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Localhost not working after installing PHP on Mountain Lion

- by zen

I've installed php using brew install php54 --with-mysql, I've set up all the path correctly. which php will give me /usr/local/bin/php php -v will give me PHP 5.4.8 (cli) (built: Nov 20 2012 09:29:31) php --ini will give me: Configuration File (php.ini) Path: /usr/local/etc/php/5.4 Loaded Configuration File: /usr/local/etc/php/5.4/php.ini Scan for additional .ini files in: /usr/local/etc/php/5.4/conf.d Additional .ini files parsed: (none) apachectl -V | grep httpd.conf will give me -D SERVER_CONFIG_FILE="/private/etc/apache2/httpd.conf" I believe everything is correct, but after I restarted my apache I keep getting error Service Temporarily Unavailable The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later. This is my httpd.conf file: # # This is the main Apache HTTP server configuration file. It contains the # configuration directives that give the server its instructions. # See <URL:http://httpd.apache.org/docs/2.2> for detailed information. # In particular, see # <URL:http://httpd.apache.org/docs/2.2/mod/directives.html> # for a discussion of each configuration directive. # # Do NOT simply read the instructions in here without understanding # what they do. They're here only as hints or reminders. If you are unsure # consult the online docs. You have been warned. # # Configuration and logfile names: If the filenames you specify for many # of the server's control files begin with "/" (or "drive:/" for Win32), the # server will use that explicit path. If the filenames do *not* begin # with "/", the value of ServerRoot is prepended -- so "log/foo_log" # with ServerRoot set to "/usr" will be interpreted by the # server as "/usr/log/foo_log". # # ServerRoot: The top of the directory tree under which the server's # configuration, error, and log files are kept. # # Do not add a slash at the end of the directory path. If you point # ServerRoot at a non-local disk, be sure to point the LockFile directive # at a local disk. If you wish to share the same ServerRoot for multiple # httpd daemons, you will need to change at least LockFile and PidFile. # ServerRoot "/usr" # # Listen: Allows you to bind Apache to specific IP addresses and/or # ports, instead of the default. See also the <VirtualHost> # directive. # # Change this to Listen on specific IP addresses as shown below to # prevent Apache from glomming onto all bound IP addresses. # #Listen 12.34.56.78:80 Listen 127.0.0.1:80 # # Dynamic Shared Object (DSO) Support # # To be able to use the functionality of a module which was built as a DSO you # have to place corresponding `LoadModule' lines at this location so the # directives contained in it are actually available _before_ they are used. # Statically compiled modules (those listed by `httpd -l') do not need # to be loaded here. # # Example: # LoadModule foo_module modules/mod_foo.so # LoadModule authn_file_module libexec/apache2/mod_authn_file.so LoadModule authn_dbm_module libexec/apache2/mod_authn_dbm.so LoadModule authn_anon_module libexec/apache2/mod_authn_anon.so LoadModule authn_dbd_module libexec/apache2/mod_authn_dbd.so LoadModule authn_default_module libexec/apache2/mod_authn_default.so LoadModule authz_host_module libexec/apache2/mod_authz_host.so LoadModule authz_groupfile_module libexec/apache2/mod_authz_groupfile.so LoadModule authz_user_module libexec/apache2/mod_authz_user.so LoadModule authz_dbm_module libexec/apache2/mod_authz_dbm.so LoadModule authz_owner_module libexec/apache2/mod_authz_owner.so LoadModule authz_default_module libexec/apache2/mod_authz_default.so LoadModule auth_basic_module libexec/apache2/mod_auth_basic.so LoadModule auth_digest_module libexec/apache2/mod_auth_digest.so LoadModule cache_module libexec/apache2/mod_cache.so LoadModule disk_cache_module libexec/apache2/mod_disk_cache.so LoadModule mem_cache_module libexec/apache2/mod_mem_cache.so LoadModule dbd_module libexec/apache2/mod_dbd.so LoadModule dumpio_module libexec/apache2/mod_dumpio.so LoadModule reqtimeout_module libexec/apache2/mod_reqtimeout.so LoadModule ext_filter_module libexec/apache2/mod_ext_filter.so LoadModule include_module libexec/apache2/mod_include.so LoadModule filter_module libexec/apache2/mod_filter.so LoadModule substitute_module libexec/apache2/mod_substitute.so LoadModule deflate_module libexec/apache2/mod_deflate.so LoadModule log_config_module libexec/apache2/mod_log_config.so LoadModule log_forensic_module libexec/apache2/mod_log_forensic.so LoadModule logio_module libexec/apache2/mod_logio.so LoadModule env_module libexec/apache2/mod_env.so LoadModule mime_magic_module libexec/apache2/mod_mime_magic.so LoadModule cern_meta_module libexec/apache2/mod_cern_meta.so LoadModule expires_module libexec/apache2/mod_expires.so LoadModule headers_module libexec/apache2/mod_headers.so LoadModule ident_module libexec/apache2/mod_ident.so LoadModule usertrack_module libexec/apache2/mod_usertrack.so #LoadModule unique_id_module libexec/apache2/mod_unique_id.so LoadModule setenvif_module libexec/apache2/mod_setenvif.so LoadModule version_module libexec/apache2/mod_version.so LoadModule proxy_module libexec/apache2/mod_proxy.so LoadModule proxy_connect_module libexec/apache2/mod_proxy_connect.so LoadModule proxy_ftp_module libexec/apache2/mod_proxy_ftp.so LoadModule proxy_http_module libexec/apache2/mod_proxy_http.so LoadModule proxy_scgi_module libexec/apache2/mod_proxy_scgi.so LoadModule proxy_ajp_module libexec/apache2/mod_proxy_ajp.so LoadModule proxy_balancer_module libexec/apache2/mod_proxy_balancer.so LoadModule ssl_module libexec/apache2/mod_ssl.so LoadModule mime_module libexec/apache2/mod_mime.so LoadModule dav_module libexec/apache2/mod_dav.so LoadModule status_module libexec/apache2/mod_status.so LoadModule autoindex_module libexec/apache2/mod_autoindex.so LoadModule asis_module libexec/apache2/mod_asis.so LoadModule info_module libexec/apache2/mod_info.so LoadModule cgi_module libexec/apache2/mod_cgi.so LoadModule dav_fs_module libexec/apache2/mod_dav_fs.so LoadModule vhost_alias_module libexec/apache2/mod_vhost_alias.so LoadModule negotiation_module libexec/apache2/mod_negotiation.so LoadModule dir_module libexec/apache2/mod_dir.so LoadModule imagemap_module libexec/apache2/mod_imagemap.so LoadModule actions_module libexec/apache2/mod_actions.so LoadModule speling_module libexec/apache2/mod_speling.so LoadModule userdir_module libexec/apache2/mod_userdir.so LoadModule alias_module libexec/apache2/mod_alias.so LoadModule rewrite_module libexec/apache2/mod_rewrite.so #LoadModule perl_module libexec/apache2/mod_perl.so LoadModule php5_module local/Cellar/php54/5.4.8/libexec/apache2/libphp5.so #LoadModule hfs_apple_module libexec/apache2/mod_hfs_apple.so <IfModule !mpm_netware_module> <IfModule !mpm_winnt_module> # # If you wish httpd to run as a different user or group, you must run # httpd as root initially and it will switch. # # User/Group: The name (or #number) of the user/group to run httpd as. # It is usually good practice to create a dedicated user and group for # running httpd, as with most system services. # User _www Group _www </IfModule> </IfModule> # 'Main' server configuration # # The directives in this section set up the values used by the 'main' # server, which responds to any requests that aren't handled by a # <VirtualHost> definition. These values also provide defaults for # any <VirtualHost> containers you may define later in the file. # # All of these directives may appear inside <VirtualHost> containers, # in which case these default settings will be overridden for the # virtual host being defined. # # # ServerAdmin: Your address, where problems with the server should be # e-mailed. This address appears on some server-generated pages, such # as error documents. e.g. [email protected] # ServerAdmin [email protected] # # ServerName gives the name and port that the server uses to identify itself. # This can often be determined automatically, but we recommend you specify # it explicitly to prevent problems during startup. # # If your host doesn't have a registered DNS name, enter its IP address here. # #ServerName www.example.com:80 # # DocumentRoot: The directory out of which you will serve your # documents. By default, all requests are taken from this directory, but # symbolic links and aliases may be used to point to other locations. # DocumentRoot "/Library/WebServer/Documents" # # Each directory to which Apache has access can be configured with respect # to which services and features are allowed and/or disabled in that # directory (and its subdirectories). # # First, we configure the "default" to be a very restrictive set of # features. # <Directory /> Options FollowSymLinks AllowOverride None Order deny,allow Deny from all </Directory> # # Note that from this point forward you must specifically allow # particular features to be enabled - so if something's not working as # you might expect, make sure that you have specifically enabled it # below. # # # This should be changed to whatever you set DocumentRoot to. # <Directory "/Library/WebServer/Documents"> # # Possible values for the Options directive are "None", "All", # or any combination of: # Indexes Includes FollowSymLinks SymLinksifOwnerMatch ExecCGI MultiViews # # Note that "MultiViews" must be named *explicitly* --- "Options All" # doesn't give it to you. # # The Options directive is both complicated and important. Please see # http://httpd.apache.org/docs/2.2/mod/core.html#options # for more information. # Options Indexes FollowSymLinks MultiViews # # AllowOverride controls what directives may be placed in .htaccess files. # It can be "All", "None", or any combination of the keywords: # Options FileInfo AuthConfig Limit # AllowOverride None # # Controls who can get stuff from this server. # Order allow,deny Allow from all </Directory> # # DirectoryIndex: sets the file that Apache will serve if a directory # is requested. # <IfModule dir_module> DirectoryIndex index.html </IfModule> # # The following lines prevent .htaccess and .htpasswd files from being # viewed by Web clients. # <FilesMatch "^\.([Hh][Tt]|[Dd][Ss]_[Ss])"> Order allow,deny Deny from all Satisfy All </FilesMatch> # # Apple specific filesystem protection. # <Files "rsrc"> Order allow,deny Deny from all Satisfy All </Files> <DirectoryMatch ".*\.\.namedfork"> Order allow,deny Deny from all Satisfy All </DirectoryMatch> # # ErrorLog: The location of the error log file. # If you do not specify an ErrorLog directive within a <VirtualHost> # container, error messages relating to that virtual host will be # logged here. If you *do* define an error logfile for a <VirtualHost> # container, that host's errors will be logged there and not here. # ErrorLog "/private/var/log/apache2/error_log" # # LogLevel: Control the number of messages logged to the error_log. # Possible values include: debug, info, notice, warn, error, crit, # alert, emerg. # LogLevel warn <IfModule log_config_module> # # The following directives define some format nicknames for use with # a CustomLog directive (see below). # LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" combined LogFormat "%h %l %u %t \"%r\" %>s %b" common <IfModule logio_module> # You need to enable mod_logio.c to use %I and %O LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\" %I %O" combinedio </IfModule> # # The location and format of the access logfile (Common Logfile Format). # If you do not define any access logfiles within a <VirtualHost> # container, they will be logged here. Contrariwise, if you *do* # define per-<VirtualHost> access logfiles, transactions will be # logged therein and *not* in this file. # CustomLog "/private/var/log/apache2/access_log" common # # If you prefer a logfile with access, agent, and referer information # (Combined Logfile Format) you can use the following directive. # #CustomLog "/private/var/log/apache2/access_log" combined </IfModule> <IfModule alias_module> # # Redirect: Allows you to tell clients about documents that used to # exist in your server's namespace, but do not anymore. The client # will make a new request for the document at its new location. # Example: # Redirect permanent /foo http://www.example.com/bar # # Alias: Maps web paths into filesystem paths and is used to # access content that does not live under the DocumentRoot. # Example: # Alias /webpath /full/filesystem/path # # If you include a trailing / on /webpath then the server will # require it to be present in the URL. You will also likely # need to provide a <Directory> section to allow access to # the filesystem path. # # ScriptAlias: This controls which directories contain server scripts. # ScriptAliases are essentially the same as Aliases, except that # documents in the target directory are treated as applications and # run by the server when requested rather than as documents sent to the # client. The same rules about trailing "/" apply to ScriptAlias # directives as to Alias. # ScriptAliasMatch ^/cgi-bin/((?!(?i:webobjects)).*$) "/Library/WebServer/CGI-Executables/$1" </IfModule> <IfModule cgid_module> # # ScriptSock: On threaded servers, designate the path to the UNIX # socket used to communicate with the CGI daemon of mod_cgid. # #Scriptsock /private/var/run/cgisock </IfModule> # # "/Library/WebServer/CGI-Executables" should be changed to whatever your ScriptAliased # CGI directory exists, if you have that configured. # <Directory "/Library/WebServer/CGI-Executables"> AllowOverride None Options None Order allow,deny Allow from all </Directory> # # DefaultType: the default MIME type the server will use for a document # if it cannot otherwise determine one, such as from filename extensions. # If your server contains mostly text or HTML documents, "text/plain" is # a good value. If most of your content is binary, such as applications # or images, you may want to use "application/octet-stream" instead to # keep browsers from trying to display binary files as though they are # text. # DefaultType text/plain <IfModule mime_module> # # TypesConfig points to the file containing the list of mappings from # filename extension to MIME-type. # TypesConfig /private/etc/apache2/mime.types # # AddType allows you to add to or override the MIME configuration # file specified in TypesConfig for specific file types. # #AddType application/x-gzip .tgz # # AddEncoding allows you to have certain browsers uncompress # information on the fly. Note: Not all browsers support this. # #AddEncoding x-compress .Z #AddEncoding x-gzip .gz .tgz # # If the AddEncoding directives above are commented-out, then you # probably should define those extensions to indicate media types: # AddType application/x-compress .Z AddType application/x-gzip .gz .tgz # # AddHandler allows you to map certain file extensions to "handlers": # actions unrelated to filetype. These can be either built into the server # or added with the Action directive (see below) # # To use CGI scripts outside of ScriptAliased directories: # (You will also need to add "ExecCGI" to the "Options" directive.) # #AddHandler cgi-script .cgi # For type maps (negotiated resources): #AddHandler type-map var # # Filters allow you to process content before it is sent to the client. # # To parse .shtml files for server-side includes (SSI): # (You will also need to add "Includes" to the "Options" directive.) # #AddType text/html .shtml #AddOutputFilter INCLUDES .shtml </IfModule> # # The mod_mime_magic module allows the server to use various hints from the # contents of the file itself to determine its type. The MIMEMagicFile # directive tells the module where the hint definitions are located. # #MIMEMagicFile /private/etc/apache2/magic # # Customizable error responses come in three flavors: # 1) plain text 2) local redirects 3) external redirects # # Some examples: #ErrorDocument 500 "The server made a boo boo." #ErrorDocument 404 /missing.html #ErrorDocument 404 "/cgi-bin/missing_handler.pl" #ErrorDocument 402 http://www.example.com/subscription_info.html # # # MaxRanges: Maximum number of Ranges in a request before # returning the entire resource, or one of the special # values 'default', 'none' or 'unlimited'. # Default setting is to accept 200 Ranges. #MaxRanges unlimited # # EnableMMAP and EnableSendfile: On systems that support it, # memory-mapping or the sendfile syscall is used to deliver # files. This usually improves server performance, but must # be turned off when serving from networked-mounted # filesystems or if support for these functions is otherwise # broken on your system. # #EnableMMAP off #EnableSendfile off # 6894961 TraceEnable off # Supplemental configuration # # The configuration files in the /private/etc/apache2/extra/ directory can be # included to add extra features or to modify the default configuration of # the server, or you may simply copy their contents here and change as # necessary. # Server-pool management (MPM specific) Include /private/etc/apache2/extra/httpd-mpm.conf # Multi-language error messages #Include /private/etc/apache2/extra/httpd-multilang-errordoc.conf # Fancy directory listings Include /private/etc/apache2/extra/httpd-autoindex.conf # Language settings Include /private/etc/apache2/extra/httpd-languages.conf # User home directories Include /private/etc/apache2/extra/httpd-userdir.conf # Real-time info on requests and configuration #Include /private/etc/apache2/extra/httpd-info.conf # Virtual hosts #Include /private/etc/apache2/extra/httpd-vhosts.conf # Local access to the Apache HTTP Server Manual Include /private/etc/apache2/extra/httpd-manual.conf # Distributed authoring and versioning (WebDAV) #Include /private/etc/apache2/extra/httpd-dav.conf # Various default settings #Include /private/etc/apache2/extra/httpd-default.conf # Secure (SSL/TLS) connections #Include /private/etc/apache2/extra/httpd-ssl.conf # # Note: The following must must be present to support # starting without SSL on platforms with no /dev/random equivalent # but a statically compiled-in mod_ssl. # <IfModule ssl_module> SSLRandomSeed startup builtin SSLRandomSeed connect builtin </IfModule> Include /private/etc/apache2/other/*.conf Please help me, I've spent 2 days trying to make it work. Btw error log keep saying [Tue Nov 20 10:47:40 2012] [error] proxy: HTTP: disabled connection for (localhost) and [Tue Nov 20 11:59:32 2012] [error] (61)Connection refused: proxy: HTTP: attempt to connect to [fe80::1]:20559 (localhost) failed

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New features of C# 4.0

This article covers New features of C# 4.0. Article has been divided into below sections. Introduction. Dynamic Lookup. Named and Optional Arguments. Features for COM interop. Variance. Relationship with Visual Basic. Resources. Other interested readings… 22 New Features of Visual Studio 2008 for .NET Professionals 50 New Features of SQL Server 2008 IIS 7.0 New features Introduction It is now close to a year since Microsoft Visual C# 3.0 shipped as part of Visual Studio 2008. In the VS Managed Languages team we are hard at work on creating the next version of the language (with the unsurprising working title of C# 4.0), and this document is a first public description of the planned language features as we currently see them. Please be advised that all this is in early stages of production and is subject to change. Part of the reason for sharing our plans in public so early is precisely to get the kind of feedback that will cause us to improve the final product before it rolls out. Simultaneously with the publication of this whitepaper, a first public CTP (community technology preview) of Visual Studio 2010 is going out as a Virtual PC image for everyone to try. Please use it to play and experiment with the features, and let us know of any thoughts you have. We ask for your understanding and patience working with very early bits, where especially new or newly implemented features do not have the quality or stability of a final product. The aim of the CTP is not to give you a productive work environment but to give you the best possible impression of what we are working on for the next release. The CTP contains a number of walkthroughs, some of which highlight the new language features of C# 4.0. Those are excellent for getting a hands-on guided tour through the details of some common scenarios for the features. You may consider this whitepaper a companion document to these walkthroughs, complementing them with a focus on the overall language features and how they work, as opposed to the specifics of the concrete scenarios. C# 4.0 The major theme for C# 4.0 is dynamic programming. Increasingly, objects are “dynamic” in the sense that their structure and behavior is not captured by a static type, or at least not one that the compiler knows about when compiling your program. Some examples include a. objects from dynamic programming languages, such as Python or Ruby b. COM objects accessed through IDispatch c. ordinary .NET types accessed through reflection d. objects with changing structure, such as HTML DOM objects While C# remains a statically typed language, we aim to vastly improve the interaction with such objects. A secondary theme is co-evolution with Visual Basic. Going forward we will aim to maintain the individual character of each language, but at the same time important new features should be introduced in both languages at the same time. They should be differentiated more by style and feel than by feature set. The new features in C# 4.0 fall into four groups: Dynamic lookup Dynamic lookup allows you to write method, operator and indexer calls, property and field accesses, and even object invocations which bypass the C# static type checking and instead gets resolved at runtime. Named and optional parameters Parameters in C# can now be specified as optional by providing a default value for them in a member declaration. When the member is invoked, optional arguments can be omitted. Furthermore, any argument can be passed by parameter name instead of position. COM specific interop features Dynamic lookup as well as named and optional parameters both help making programming against COM less painful than today. On top of that, however, we are adding a number of other small features that further improve the interop experience. Variance It used to be that an IEnumerable<string> wasn’t an IEnumerable<object>. Now it is – C# embraces type safe “co-and contravariance” and common BCL types are updated to take advantage of that. Dynamic Lookup Dynamic lookup allows you a unified approach to invoking things dynamically. With dynamic lookup, when you have an object in your hand you do not need to worry about whether it comes from COM, IronPython, the HTML DOM or reflection; you just apply operations to it and leave it to the runtime to figure out what exactly those operations mean for that particular object. This affords you enormous flexibility, and can greatly simplify your code, but it does come with a significant drawback: Static typing is not maintained for these operations. A dynamic object is assumed at compile time to support any operation, and only at runtime will you get an error if it wasn’t so. Oftentimes this will be no loss, because the object wouldn’t have a static type anyway, in other cases it is a tradeoff between brevity and safety. In order to facilitate this tradeoff, it is a design goal of C# to allow you to opt in or opt out of dynamic behavior on every single call. The dynamic type C# 4.0 introduces a new static type called dynamic. When you have an object of type dynamic you can “do things to it” that are resolved only at runtime: dynamic d = GetDynamicObject(…); d.M(7); The C# compiler allows you to call a method with any name and any arguments on d because it is of type dynamic. At runtime the actual object that d refers to will be examined to determine what it means to “call M with an int” on it. The type dynamic can be thought of as a special version of the type object, which signals that the object can be used dynamically. It is easy to opt in or out of dynamic behavior: any object can be implicitly converted to dynamic, “suspending belief” until runtime. Conversely, there is an “assignment conversion” from dynamic to any other type, which allows implicit conversion in assignment-like constructs: dynamic d = 7; // implicit conversion int i = d; // assignment conversion Dynamic operations Not only method calls, but also field and property accesses, indexer and operator calls and even delegate invocations can be dispatched dynamically: dynamic d = GetDynamicObject(…); d.M(7); // calling methods d.f = d.P; // getting and settings fields and properties d[“one”] = d[“two”]; // getting and setting thorugh indexers int i = d + 3; // calling operators string s = d(5,7); // invoking as a delegate The role of the C# compiler here is simply to package up the necessary information about “what is being done to d”, so that the runtime can pick it up and determine what the exact meaning of it is given an actual object d. Think of it as deferring part of the compiler’s job to runtime. The result of any dynamic operation is itself of type dynamic. Runtime lookup At runtime a dynamic operation is dispatched according to the nature of its target object d: COM objects If d is a COM object, the operation is dispatched dynamically through COM IDispatch. This allows calling to COM types that don’t have a Primary Interop Assembly (PIA), and relying on COM features that don’t have a counterpart in C#, such as indexed properties and default properties. Dynamic objects If d implements the interface IDynamicObject d itself is asked to perform the operation. Thus by implementing IDynamicObject a type can completely redefine the meaning of dynamic operations. This is used intensively by dynamic languages such as IronPython and IronRuby to implement their own dynamic object models. It will also be used by APIs, e.g. by the HTML DOM to allow direct access to the object’s properties using property syntax. Plain objects Otherwise d is a standard .NET object, and the operation will be dispatched using reflection on its type and a C# “runtime binder” which implements C#’s lookup and overload resolution semantics at runtime. This is essentially a part of the C# compiler running as a runtime component to “finish the work” on dynamic operations that was deferred by the static compiler. Example Assume the following code: dynamic d1 = new Foo(); dynamic d2 = new Bar(); string s; d1.M(s, d2, 3, null); Because the receiver of the call to M is dynamic, the C# compiler does not try to resolve the meaning of the call. Instead it stashes away information for the runtime about the call. This information (often referred to as the “payload”) is essentially equivalent to: “Perform an instance method call of M with the following arguments: 1. a string 2. a dynamic 3. a literal int 3 4. a literal object null” At runtime, assume that the actual type Foo of d1 is not a COM type and does not implement IDynamicObject. In this case the C# runtime binder picks up to finish the overload resolution job based on runtime type information, proceeding as follows: 1. Reflection is used to obtain the actual runtime types of the two objects, d1 and d2, that did not have a static type (or rather had the static type dynamic). The result is Foo for d1 and Bar for d2. 2. Method lookup and overload resolution is performed on the type Foo with the call M(string,Bar,3,null) using ordinary C# semantics. 3. If the method is found it is invoked; otherwise a runtime exception is thrown. Overload resolution with dynamic arguments Even if the receiver of a method call is of a static type, overload resolution can still happen at runtime. This can happen if one or more of the arguments have the type dynamic: Foo foo = new Foo(); dynamic d = new Bar(); var result = foo.M(d); The C# runtime binder will choose between the statically known overloads of M on Foo, based on the runtime type of d, namely Bar. The result is again of type dynamic. The Dynamic Language Runtime An important component in the underlying implementation of dynamic lookup is the Dynamic Language Runtime (DLR), which is a new API in .NET 4.0. The DLR provides most of the infrastructure behind not only C# dynamic lookup but also the implementation of several dynamic programming languages on .NET, such as IronPython and IronRuby. Through this common infrastructure a high degree of interoperability is ensured, but just as importantly the DLR provides excellent caching mechanisms which serve to greatly enhance the efficiency of runtime dispatch. To the user of dynamic lookup in C#, the DLR is invisible except for the improved efficiency. However, if you want to implement your own dynamically dispatched objects, the IDynamicObject interface allows you to interoperate with the DLR and plug in your own behavior. This is a rather advanced task, which requires you to understand a good deal more about the inner workings of the DLR. For API writers, however, it can definitely be worth the trouble in order to vastly improve the usability of e.g. a library representing an inherently dynamic domain. Open issues There are a few limitations and things that might work differently than you would expect. · The DLR allows objects to be created from objects that represent classes. However, the current implementation of C# doesn’t have syntax to support this. · Dynamic lookup will not be able to find extension methods. Whether extension methods apply or not depends on the static context of the call (i.e. which using clauses occur), and this context information is not currently kept as part of the payload. · Anonymous functions (i.e. lambda expressions) cannot appear as arguments to a dynamic method call. The compiler cannot bind (i.e. “understand”) an anonymous function without knowing what type it is converted to. One consequence of these limitations is that you cannot easily use LINQ queries over dynamic objects: dynamic collection = …; var result = collection.Select(e => e + 5); If the Select method is an extension method, dynamic lookup will not find it. Even if it is an instance method, the above does not compile, because a lambda expression cannot be passed as an argument to a dynamic operation. There are no plans to address these limitations in C# 4.0. Named and Optional Arguments Named and optional parameters are really two distinct features, but are often useful together. Optional parameters allow you to omit arguments to member invocations, whereas named arguments is a way to provide an argument using the name of the corresponding parameter instead of relying on its position in the parameter list. Some APIs, most notably COM interfaces such as the Office automation APIs, are written specifically with named and optional parameters in mind. Up until now it has been very painful to call into these APIs from C#, with sometimes as many as thirty arguments having to be explicitly passed, most of which have reasonable default values and could be omitted. Even in APIs for .NET however you sometimes find yourself compelled to write many overloads of a method with different combinations of parameters, in order to provide maximum usability to the callers. Optional parameters are a useful alternative for these situations. Optional parameters A parameter is declared optional simply by providing a default value for it: public void M(int x, int y = 5, int z = 7); Here y and z are optional parameters and can be omitted in calls: M(1, 2, 3); // ordinary call of M M(1, 2); // omitting z – equivalent to M(1, 2, 7) M(1); // omitting both y and z – equivalent to M(1, 5, 7) Named and optional arguments C# 4.0 does not permit you to omit arguments between commas as in M(1,,3). This could lead to highly unreadable comma-counting code. Instead any argument can be passed by name. Thus if you want to omit only y from a call of M you can write: M(1, z: 3); // passing z by name or M(x: 1, z: 3); // passing both x and z by name or even M(z: 3, x: 1); // reversing the order of arguments All forms are equivalent, except that arguments are always evaluated in the order they appear, so in the last example the 3 is evaluated before the 1. Optional and named arguments can be used not only with methods but also with indexers and constructors. Overload resolution Named and optional arguments affect overload resolution, but the changes are relatively simple: A signature is applicable if all its parameters are either optional or have exactly one corresponding argument (by name or position) in the call which is convertible to the parameter type. Betterness rules on conversions are only applied for arguments that are explicitly given – omitted optional arguments are ignored for betterness purposes. If two signatures are equally good, one that does not omit optional parameters is preferred. M(string s, int i = 1); M(object o); M(int i, string s = “Hello”); M(int i); M(5); Given these overloads, we can see the working of the rules above. M(string,int) is not applicable because 5 doesn’t convert to string. M(int,string) is applicable because its second parameter is optional, and so, obviously are M(object) and M(int). M(int,string) and M(int) are both better than M(object) because the conversion from 5 to int is better than the conversion from 5 to object. Finally M(int) is better than M(int,string) because no optional arguments are omitted. Thus the method that gets called is M(int). Features for COM interop Dynamic lookup as well as named and optional parameters greatly improve the experience of interoperating with COM APIs such as the Office Automation APIs. In order to remove even more of the speed bumps, a couple of small COM-specific features are also added to C# 4.0. Dynamic import Many COM methods accept and return variant types, which are represented in the PIAs as object. In the vast majority of cases, a programmer calling these methods already knows the static type of a returned object from context, but explicitly has to perform a cast on the returned value to make use of that knowledge. These casts are so common that they constitute a major nuisance. In order to facilitate a smoother experience, you can now choose to import these COM APIs in such a way that variants are instead represented using the type dynamic. In other words, from your point of view, COM signatures now have occurrences of dynamic instead of object in them. This means that you can easily access members directly off a returned object, or you can assign it to a strongly typed local variable without having to cast. To illustrate, you can now say excel.Cells[1, 1].Value = "Hello"; instead of ((Excel.Range)excel.Cells[1, 1]).Value2 = "Hello"; and Excel.Range range = excel.Cells[1, 1]; instead of Excel.Range range = (Excel.Range)excel.Cells[1, 1]; Compiling without PIAs Primary Interop Assemblies are large .NET assemblies generated from COM interfaces to facilitate strongly typed interoperability. They provide great support at design time, where your experience of the interop is as good as if the types where really defined in .NET. However, at runtime these large assemblies can easily bloat your program, and also cause versioning issues because they are distributed independently of your application. The no-PIA feature allows you to continue to use PIAs at design time without having them around at runtime. Instead, the C# compiler will bake the small part of the PIA that a program actually uses directly into its assembly. At runtime the PIA does not have to be loaded. Omitting ref Because of a different programming model, many COM APIs contain a lot of reference parameters. Contrary to refs in C#, these are typically not meant to mutate a passed-in argument for the subsequent benefit of the caller, but are simply another way of passing value parameters. It therefore seems unreasonable that a C# programmer should have to create temporary variables for all such ref parameters and pass these by reference. Instead, specifically for COM methods, the C# compiler will allow you to pass arguments by value to such a method, and will automatically generate temporary variables to hold the passed-in values, subsequently discarding these when the call returns. In this way the caller sees value semantics, and will not experience any side effects, but the called method still gets a reference. Open issues A few COM interface features still are not surfaced in C#. Most notably these include indexed properties and default properties. As mentioned above these will be respected if you access COM dynamically, but statically typed C# code will still not recognize them. There are currently no plans to address these remaining speed bumps in C# 4.0. Variance An aspect of generics that often comes across as surprising is that the following is illegal: IList<string> strings = new List<string>(); IList<object> objects = strings; The second assignment is disallowed because strings does not have the same element type as objects. There is a perfectly good reason for this. If it were allowed you could write: objects[0] = 5; string s = strings[0]; Allowing an int to be inserted into a list of strings and subsequently extracted as a string. This would be a breach of type safety. However, there are certain interfaces where the above cannot occur, notably where there is no way to insert an object into the collection. Such an interface is IEnumerable<T>. If instead you say: IEnumerable<object> objects = strings; There is no way we can put the wrong kind of thing into strings through objects, because objects doesn’t have a method that takes an element in. Variance is about allowing assignments such as this in cases where it is safe. The result is that a lot of situations that were previously surprising now just work. Covariance In .NET 4.0 the IEnumerable<T> interface will be declared in the following way: public interface IEnumerable<out T> : IEnumerable { IEnumerator<T> GetEnumerator(); } public interface IEnumerator<out T> : IEnumerator { bool MoveNext(); T Current { get; } } The “out” in these declarations signifies that the T can only occur in output position in the interface – the compiler will complain otherwise. In return for this restriction, the interface becomes “covariant” in T, which means that an IEnumerable<A> is considered an IEnumerable<B> if A has a reference conversion to B. As a result, any sequence of strings is also e.g. a sequence of objects. This is useful e.g. in many LINQ methods. Using the declarations above: var result = strings.Union(objects); // succeeds with an IEnumerable<object> This would previously have been disallowed, and you would have had to to some cumbersome wrapping to get the two sequences to have the same element type. Contravariance Type parameters can also have an “in” modifier, restricting them to occur only in input positions. An example is IComparer<T>: public interface IComparer<in T> { public int Compare(T left, T right); } The somewhat baffling result is that an IComparer<object> can in fact be considered an IComparer<string>! It makes sense when you think about it: If a comparer can compare any two objects, it can certainly also compare two strings. This property is referred to as contravariance. A generic type can have both in and out modifiers on its type parameters, as is the case with the Func<…> delegate types: public delegate TResult Func<in TArg, out TResult>(TArg arg); Obviously the argument only ever comes in, and the result only ever comes out. Therefore a Func<object,string> can in fact be used as a Func<string,object>. Limitations Variant type parameters can only be declared on interfaces and delegate types, due to a restriction in the CLR. Variance only applies when there is a reference conversion between the type arguments. For instance, an IEnumerable<int> is not an IEnumerable<object> because the conversion from int to object is a boxing conversion, not a reference conversion. Also please note that the CTP does not contain the new versions of the .NET types mentioned above. In order to experiment with variance you have to declare your own variant interfaces and delegate types. COM Example Here is a larger Office automation example that shows many of the new C# features in action. using System; using System.Diagnostics; using System.Linq; using Excel = Microsoft.Office.Interop.Excel; using Word = Microsoft.Office.Interop.Word; class Program { static void Main(string[] args) { var excel = new Excel.Application(); excel.Visible = true; excel.Workbooks.Add(); // optional arguments omitted excel.Cells[1, 1].Value = "Process Name"; // no casts; Value dynamically excel.Cells[1, 2].Value = "Memory Usage"; // accessed var processes = Process.GetProcesses() .OrderByDescending(p => p.WorkingSet) .Take(10); int i = 2; foreach (var p in processes) { excel.Cells[i, 1].Value = p.ProcessName; // no casts excel.Cells[i, 2].Value = p.WorkingSet; // no casts i++; } Excel.Range range = excel.Cells[1, 1]; // no casts Excel.Chart chart = excel.ActiveWorkbook.Charts. Add(After: excel.ActiveSheet); // named and optional arguments chart.ChartWizard( Source: range.CurrentRegion, Title: "Memory Usage in " + Environment.MachineName); //named+optional chart.ChartStyle = 45; chart.CopyPicture(Excel.XlPictureAppearance.xlScreen, Excel.XlCopyPictureFormat.xlBitmap, Excel.XlPictureAppearance.xlScreen); var word = new Word.Application(); word.Visible = true; word.Documents.Add(); // optional arguments word.Selection.Paste(); } } The code is much more terse and readable than the C# 3.0 counterpart. Note especially how the Value property is accessed dynamically. This is actually an indexed property, i.e. a property that takes an argument; something which C# does not understand. However the argument is optional. Since the access is dynamic, it goes through the runtime COM binder which knows to substitute the default value and call the indexed property. Thus, dynamic COM allows you to avoid accesses to the puzzling Value2 property of Excel ranges. Relationship with Visual Basic A number of the features introduced to C# 4.0 already exist or will be introduced in some form or other in Visual Basic: · Late binding in VB is similar in many ways to dynamic lookup in C#, and can be expected to make more use of the DLR in the future, leading to further parity with C#. · Named and optional arguments have been part of Visual Basic for a long time, and the C# version of the feature is explicitly engineered with maximal VB interoperability in mind. · NoPIA and variance are both being introduced to VB and C# at the same time. VB in turn is adding a number of features that have hitherto been a mainstay of C#. As a result future versions of C# and VB will have much better feature parity, for the benefit of everyone. Resources All available resources concerning C# 4.0 can be accessed through the C# Dev Center. Specifically, this white paper and other resources can be found at the Code Gallery site. Enjoy! span.fullpost {display:none;}

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Introduction to the ASP.NET Web API

- by Stephen.Walther

I am a huge fan of Ajax. If you want to create a great experience for the users of your website – regardless of whether you are building an ASP.NET MVC or an ASP.NET Web Forms site — then you need to use Ajax. Otherwise, you are just being cruel to your customers. We use Ajax extensively in several of the ASP.NET applications that my company, Superexpert.com, builds. We expose data from the server as JSON and use jQuery to retrieve and update that data from the browser. One challenge, when building an ASP.NET website, is deciding on which technology to use to expose JSON data from the server. For example, how do you expose a list of products from the server as JSON so you can retrieve the list of products with jQuery? You have a number of options (too many options) including ASMX Web services, WCF Web Services, ASHX Generic Handlers, WCF Data Services, and MVC controller actions. Fortunately, the world has just been simplified. With the release of ASP.NET 4 Beta, Microsoft has introduced a new technology for exposing JSON from the server named the ASP.NET Web API. You can use the ASP.NET Web API with both ASP.NET MVC and ASP.NET Web Forms applications. The goal of this blog post is to provide you with a brief overview of the features of the new ASP.NET Web API. You learn how to use the ASP.NET Web API to retrieve, insert, update, and delete database records with jQuery. We also discuss how you can perform form validation when using the Web API and use OData when using the Web API. Creating an ASP.NET Web API Controller The ASP.NET Web API exposes JSON data through a new type of controller called an API controller. You can add an API controller to an existing ASP.NET MVC 4 project through the standard Add Controller dialog box. Right-click your Controllers folder and select Add, Controller. In the dialog box, name your controller MovieController and select the Empty API controller template: A brand new API controller looks like this: using System; using System.Collections.Generic; using System.Linq; using System.Net.Http; using System.Web.Http; namespace MyWebAPIApp.Controllers { public class MovieController : ApiController { } } An API controller, unlike a standard MVC controller, derives from the base ApiController class instead of the base Controller class. Using jQuery to Retrieve, Insert, Update, and Delete Data Let’s create an Ajaxified Movie Database application. We’ll retrieve, insert, update, and delete movies using jQuery with the MovieController which we just created. Our Movie model class looks like this: namespace MyWebAPIApp.Models { public class Movie { public int Id { get; set; } public string Title { get; set; } public string Director { get; set; } } } Our application will consist of a single HTML page named Movies.html. We’ll place all of our jQuery code in the Movies.html page. Getting a Single Record with the ASP.NET Web API To support retrieving a single movie from the server, we need to add a Get method to our API controller: using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Net.Http; using System.Web.Http; using MyWebAPIApp.Models; namespace MyWebAPIApp.Controllers { public class MovieController : ApiController { public Movie GetMovie(int id) { // Return movie by id if (id == 1) { return new Movie { Id = 1, Title = "Star Wars", Director = "Lucas" }; } // Otherwise, movie was not found throw new HttpResponseException(HttpStatusCode.NotFound); } } } In the code above, the GetMovie() method accepts the Id of a movie. If the Id has the value 1 then the method returns the movie Star Wars. Otherwise, the method throws an exception and returns 404 Not Found HTTP status code. After building your project, you can invoke the MovieController.GetMovie() method by entering the following URL in your web browser address bar: http://localhost:[port]/api/movie/1 (You’ll need to enter the correct randomly generated port). In the URL api/movie/1, the first “api” segment indicates that this is a Web API route. The “movie” segment indicates that the MovieController should be invoked. You do not specify the name of the action. Instead, the HTTP method used to make the request – GET, POST, PUT, DELETE — is used to identify the action to invoke. The ASP.NET Web API uses different routing conventions than normal ASP.NET MVC controllers. When you make an HTTP GET request then any API controller method with a name that starts with “GET” is invoked. So, we could have called our API controller action GetPopcorn() instead of GetMovie() and it would still be invoked by the URL api/movie/1. The default route for the Web API is defined in the Global.asax file and it looks like this: routes.MapHttpRoute( name: "DefaultApi", routeTemplate: "api/{controller}/{id}", defaults: new { id = RouteParameter.Optional } ); We can invoke our GetMovie() controller action with the jQuery code in the following HTML page: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Get Movie</title> </head> <body> <div> Title: <span id="title"></span> </div> <div> Director: <span id="director"></span> </div> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> getMovie(1, function (movie) { $("#title").html(movie.Title); $("#director").html(movie.Director); }); function getMovie(id, callback) { $.ajax({ url: "/api/Movie", data: { id: id }, type: "GET", contentType: "application/json;charset=utf-8", statusCode: { 200: function (movie) { callback(movie); }, 404: function () { alert("Not Found!"); } } }); } </script> </body> </html> In the code above, the jQuery $.ajax() method is used to invoke the GetMovie() method. Notice that the Ajax call handles two HTTP response codes. When the GetMove() method successfully returns a movie, the method returns a 200 status code. In that case, the details of the movie are displayed in the HTML page. Otherwise, if the movie is not found, the GetMovie() method returns a 404 status code. In that case, the page simply displays an alert box indicating that the movie was not found (hopefully, you would implement something more graceful in an actual application). You can use your browser’s Developer Tools to see what is going on in the background when you open the HTML page (hit F12 in the most recent version of most browsers). For example, you can use the Network tab in Google Chrome to see the Ajax request which invokes the GetMovie() method: Getting a Set of Records with the ASP.NET Web API Let’s modify our Movie API controller so that it returns a collection of movies. The following Movie controller has a new ListMovies() method which returns a (hard-coded) collection of movies: using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Net.Http; using System.Web.Http; using MyWebAPIApp.Models; namespace MyWebAPIApp.Controllers { public class MovieController : ApiController { public IEnumerable<Movie> ListMovies() { return new List<Movie> { new Movie {Id=1, Title="Star Wars", Director="Lucas"}, new Movie {Id=1, Title="King Kong", Director="Jackson"}, new Movie {Id=1, Title="Memento", Director="Nolan"} }; } } } Because we named our action ListMovies(), the default Web API route will never match it. Therefore, we need to add the following custom route to our Global.asax file (at the top of the RegisterRoutes() method): routes.MapHttpRoute( name: "ActionApi", routeTemplate: "api/{controller}/{action}/{id}", defaults: new { id = RouteParameter.Optional } ); This route enables us to invoke the ListMovies() method with the URL /api/movie/listmovies. Now that we have exposed our collection of movies from the server, we can retrieve and display the list of movies using jQuery in our HTML page: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>List Movies</title> </head> <body> <div id="movies"></div> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> listMovies(function (movies) { var strMovies=""; $.each(movies, function (index, movie) { strMovies += "<div>" + movie.Title + "</div>"; }); $("#movies").html(strMovies); }); function listMovies(callback) { $.ajax({ url: "/api/Movie/ListMovies", data: {}, type: "GET", contentType: "application/json;charset=utf-8", }).then(function(movies){ callback(movies); }); } </script> </body> </html> Inserting a Record with the ASP.NET Web API Now let’s modify our Movie API controller so it supports creating new records: public HttpResponseMessage<Movie> PostMovie(Movie movieToCreate) { // Add movieToCreate to the database and update primary key movieToCreate.Id = 23; // Build a response that contains the location of the new movie var response = new HttpResponseMessage<Movie>(movieToCreate, HttpStatusCode.Created); var relativePath = "/api/movie/" + movieToCreate.Id; response.Headers.Location = new Uri(Request.RequestUri, relativePath); return response; } The PostMovie() method in the code above accepts a movieToCreate parameter. We don’t actually store the new movie anywhere. In real life, you will want to call a service method to store the new movie in a database. When you create a new resource, such as a new movie, you should return the location of the new resource. In the code above, the URL where the new movie can be retrieved is assigned to the Location header returned in the PostMovie() response. Because the name of our method starts with “Post”, we don’t need to create a custom route. The PostMovie() method can be invoked with the URL /Movie/PostMovie – just as long as the method is invoked within the context of a HTTP POST request. The following HTML page invokes the PostMovie() method. <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Create Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> var movieToCreate = { title: "The Hobbit", director: "Jackson" }; createMovie(movieToCreate, function (newMovie) { alert("New movie created with an Id of " + newMovie.Id); }); function createMovie(movieToCreate, callback) { $.ajax({ url: "/api/Movie", data: JSON.stringify( movieToCreate ), type: "POST", contentType: "application/json;charset=utf-8", statusCode: { 201: function (newMovie) { callback(newMovie); } } }); } </script> </body> </html> This page creates a new movie (the Hobbit) by calling the createMovie() method. The page simply displays the Id of the new movie: The HTTP Post operation is performed with the following call to the jQuery $.ajax() method: $.ajax({ url: "/api/Movie", data: JSON.stringify( movieToCreate ), type: "POST", contentType: "application/json;charset=utf-8", statusCode: { 201: function (newMovie) { callback(newMovie); } } }); Notice that the type of Ajax request is a POST request. This is required to match the PostMovie() method. Notice, furthermore, that the new movie is converted into JSON using JSON.stringify(). The JSON.stringify() method takes a JavaScript object and converts it into a JSON string. Finally, notice that success is represented with a 201 status code. The HttpStatusCode.Created value returned from the PostMovie() method returns a 201 status code. Updating a Record with the ASP.NET Web API Here’s how we can modify the Movie API controller to support updating an existing record. In this case, we need to create a PUT method to handle an HTTP PUT request: public void PutMovie(Movie movieToUpdate) { if (movieToUpdate.Id == 1) { // Update the movie in the database return; } // If you can't find the movie to update throw new HttpResponseException(HttpStatusCode.NotFound); } Unlike our PostMovie() method, the PutMovie() method does not return a result. The action either updates the database or, if the movie cannot be found, returns an HTTP Status code of 404. The following HTML page illustrates how you can invoke the PutMovie() method: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Put Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> var movieToUpdate = { id: 1, title: "The Hobbit", director: "Jackson" }; updateMovie(movieToUpdate, function () { alert("Movie updated!"); }); function updateMovie(movieToUpdate, callback) { $.ajax({ url: "/api/Movie", data: JSON.stringify(movieToUpdate), type: "PUT", contentType: "application/json;charset=utf-8", statusCode: { 200: function () { callback(); }, 404: function () { alert("Movie not found!"); } } }); } </script> </body> </html> Deleting a Record with the ASP.NET Web API Here’s the code for deleting a movie: public HttpResponseMessage DeleteMovie(int id) { // Delete the movie from the database // Return status code return new HttpResponseMessage(HttpStatusCode.NoContent); } This method simply deletes the movie (well, not really, but pretend that it does) and returns a No Content status code (204). The following page illustrates how you can invoke the DeleteMovie() action: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Delete Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> deleteMovie(1, function () { alert("Movie deleted!"); }); function deleteMovie(id, callback) { $.ajax({ url: "/api/Movie", data: JSON.stringify({id:id}), type: "DELETE", contentType: "application/json;charset=utf-8", statusCode: { 204: function () { callback(); } } }); } </script> </body> </html> Performing Validation How do you perform form validation when using the ASP.NET Web API? Because validation in ASP.NET MVC is driven by the Default Model Binder, and because the Web API uses the Default Model Binder, you get validation for free. Let’s modify our Movie class so it includes some of the standard validation attributes: using System.ComponentModel.DataAnnotations; namespace MyWebAPIApp.Models { public class Movie { public int Id { get; set; } [Required(ErrorMessage="Title is required!")] [StringLength(5, ErrorMessage="Title cannot be more than 5 characters!")] public string Title { get; set; } [Required(ErrorMessage="Director is required!")] public string Director { get; set; } } } In the code above, the Required validation attribute is used to make both the Title and Director properties required. The StringLength attribute is used to require the length of the movie title to be no more than 5 characters. Now let’s modify our PostMovie() action to validate a movie before adding the movie to the database: public HttpResponseMessage PostMovie(Movie movieToCreate) { // Validate movie if (!ModelState.IsValid) { var errors = new JsonArray(); foreach (var prop in ModelState.Values) { if (prop.Errors.Any()) { errors.Add(prop.Errors.First().ErrorMessage); } } return new HttpResponseMessage<JsonValue>(errors, HttpStatusCode.BadRequest); } // Add movieToCreate to the database and update primary key movieToCreate.Id = 23; // Build a response that contains the location of the new movie var response = new HttpResponseMessage<Movie>(movieToCreate, HttpStatusCode.Created); var relativePath = "/api/movie/" + movieToCreate.Id; response.Headers.Location = new Uri(Request.RequestUri, relativePath); return response; } If ModelState.IsValid has the value false then the errors in model state are copied to a new JSON array. Each property – such as the Title and Director property — can have multiple errors. In the code above, only the first error message is copied over. The JSON array is returned with a Bad Request status code (400 status code). The following HTML page illustrates how you can invoke our modified PostMovie() action and display any error messages: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Create Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> var movieToCreate = { title: "The Hobbit", director: "" }; createMovie(movieToCreate, function (newMovie) { alert("New movie created with an Id of " + newMovie.Id); }, function (errors) { var strErrors = ""; $.each(errors, function(index, err) { strErrors += "*" + err + "\n"; }); alert(strErrors); } ); function createMovie(movieToCreate, success, fail) { $.ajax({ url: "/api/Movie", data: JSON.stringify(movieToCreate), type: "POST", contentType: "application/json;charset=utf-8", statusCode: { 201: function (newMovie) { success(newMovie); }, 400: function (xhr) { var errors = JSON.parse(xhr.responseText); fail(errors); } } }); } </script> </body> </html> The createMovie() function performs an Ajax request and handles either a 201 or a 400 status code from the response. If a 201 status code is returned then there were no validation errors and the new movie was created. If, on the other hand, a 400 status code is returned then there was a validation error. The validation errors are retrieved from the XmlHttpRequest responseText property. The error messages are displayed in an alert: (Please don’t use JavaScript alert dialogs to display validation errors, I just did it this way out of pure laziness) This validation code in our PostMovie() method is pretty generic. There is nothing specific about this code to the PostMovie() method. In the following video, Jon Galloway demonstrates how to create a global Validation filter which can be used with any API controller action: http://www.asp.net/web-api/overview/web-api-routing-and-actions/video-custom-validation His validation filter looks like this: using System.Json; using System.Linq; using System.Net; using System.Net.Http; using System.Web.Http.Controllers; using System.Web.Http.Filters; namespace MyWebAPIApp.Filters { public class ValidationActionFilter:ActionFilterAttribute { public override void OnActionExecuting(HttpActionContext actionContext) { var modelState = actionContext.ModelState; if (!modelState.IsValid) { dynamic errors = new JsonObject(); foreach (var key in modelState.Keys) { var state = modelState[key]; if (state.Errors.Any()) { errors[key] = state.Errors.First().ErrorMessage; } } actionContext.Response = new HttpResponseMessage<JsonValue>(errors, HttpStatusCode.BadRequest); } } } } And you can register the validation filter in the Application_Start() method in the Global.asax file like this: GlobalConfiguration.Configuration.Filters.Add(new ValidationActionFilter()); After you register the Validation filter, validation error messages are returned from any API controller action method automatically when validation fails. You don’t need to add any special logic to any of your API controller actions to take advantage of the filter. Querying using OData The OData protocol is an open protocol created by Microsoft which enables you to perform queries over the web. The official website for OData is located here: http://odata.org For example, here are some of the query options which you can use with OData: · $orderby – Enables you to retrieve results in a certain order. · $top – Enables you to retrieve a certain number of results. · $skip – Enables you to skip over a certain number of results (use with $top for paging). · $filter – Enables you to filter the results returned. The ASP.NET Web API supports a subset of the OData protocol. You can use all of the query options listed above when interacting with an API controller. The only requirement is that the API controller action returns its data as IQueryable. For example, the following Movie controller has an action named GetMovies() which returns an IQueryable of movies: public IQueryable<Movie> GetMovies() { return new List<Movie> { new Movie {Id=1, Title="Star Wars", Director="Lucas"}, new Movie {Id=2, Title="King Kong", Director="Jackson"}, new Movie {Id=3, Title="Willow", Director="Lucas"}, new Movie {Id=4, Title="Shrek", Director="Smith"}, new Movie {Id=5, Title="Memento", Director="Nolan"} }.AsQueryable(); } If you enter the following URL in your browser: /api/movie?$top=2&$orderby=Title Then you will limit the movies returned to the top 2 in order of the movie Title. You will get the following results: By using the $top option in combination with the $skip option, you can enable client-side paging. For example, you can use $top and $skip to page through thousands of products, 10 products at a time. The $filter query option is very powerful. You can use this option to filter the results from a query. Here are some examples: Return every movie directed by Lucas: /api/movie?$filter=Director eq ‘Lucas’ Return every movie which has a title which starts with ‘S’: /api/movie?$filter=startswith(Title,’S') Return every movie which has an Id greater than 2: /api/movie?$filter=Id gt 2 The complete documentation for the $filter option is located here: http://www.odata.org/developers/protocols/uri-conventions#FilterSystemQueryOption Summary The goal of this blog entry was to provide you with an overview of the new ASP.NET Web API introduced with the Beta release of ASP.NET 4. In this post, I discussed how you can retrieve, insert, update, and delete data by using jQuery with the Web API. I also discussed how you can use the standard validation attributes with the Web API. You learned how to return validation error messages to the client and display the error messages using jQuery. Finally, we briefly discussed how the ASP.NET Web API supports the OData protocol. For example, you learned how to filter records returned from an API controller action by using the $filter query option. I’m excited about the new Web API. This is a feature which I expect to use with almost every ASP.NET application which I build in the future.

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Introduction to the ASP.NET Web API

- by Stephen.Walther

I am a huge fan of Ajax. If you want to create a great experience for the users of your website – regardless of whether you are building an ASP.NET MVC or an ASP.NET Web Forms site — then you need to use Ajax. Otherwise, you are just being cruel to your customers. We use Ajax extensively in several of the ASP.NET applications that my company, Superexpert.com, builds. We expose data from the server as JSON and use jQuery to retrieve and update that data from the browser. One challenge, when building an ASP.NET website, is deciding on which technology to use to expose JSON data from the server. For example, how do you expose a list of products from the server as JSON so you can retrieve the list of products with jQuery? You have a number of options (too many options) including ASMX Web services, WCF Web Services, ASHX Generic Handlers, WCF Data Services, and MVC controller actions. Fortunately, the world has just been simplified. With the release of ASP.NET 4 Beta, Microsoft has introduced a new technology for exposing JSON from the server named the ASP.NET Web API. You can use the ASP.NET Web API with both ASP.NET MVC and ASP.NET Web Forms applications. The goal of this blog post is to provide you with a brief overview of the features of the new ASP.NET Web API. You learn how to use the ASP.NET Web API to retrieve, insert, update, and delete database records with jQuery. We also discuss how you can perform form validation when using the Web API and use OData when using the Web API. Creating an ASP.NET Web API Controller The ASP.NET Web API exposes JSON data through a new type of controller called an API controller. You can add an API controller to an existing ASP.NET MVC 4 project through the standard Add Controller dialog box. Right-click your Controllers folder and select Add, Controller. In the dialog box, name your controller MovieController and select the Empty API controller template: A brand new API controller looks like this: using System; using System.Collections.Generic; using System.Linq; using System.Net.Http; using System.Web.Http; namespace MyWebAPIApp.Controllers { public class MovieController : ApiController { } } An API controller, unlike a standard MVC controller, derives from the base ApiController class instead of the base Controller class. Using jQuery to Retrieve, Insert, Update, and Delete Data Let’s create an Ajaxified Movie Database application. We’ll retrieve, insert, update, and delete movies using jQuery with the MovieController which we just created. Our Movie model class looks like this: namespace MyWebAPIApp.Models { public class Movie { public int Id { get; set; } public string Title { get; set; } public string Director { get; set; } } } Our application will consist of a single HTML page named Movies.html. We’ll place all of our jQuery code in the Movies.html page. Getting a Single Record with the ASP.NET Web API To support retrieving a single movie from the server, we need to add a Get method to our API controller: using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Net.Http; using System.Web.Http; using MyWebAPIApp.Models; namespace MyWebAPIApp.Controllers { public class MovieController : ApiController { public Movie GetMovie(int id) { // Return movie by id if (id == 1) { return new Movie { Id = 1, Title = "Star Wars", Director = "Lucas" }; } // Otherwise, movie was not found throw new HttpResponseException(HttpStatusCode.NotFound); } } } In the code above, the GetMovie() method accepts the Id of a movie. If the Id has the value 1 then the method returns the movie Star Wars. Otherwise, the method throws an exception and returns 404 Not Found HTTP status code. After building your project, you can invoke the MovieController.GetMovie() method by entering the following URL in your web browser address bar: http://localhost:[port]/api/movie/1 (You’ll need to enter the correct randomly generated port). In the URL api/movie/1, the first “api” segment indicates that this is a Web API route. The “movie” segment indicates that the MovieController should be invoked. You do not specify the name of the action. Instead, the HTTP method used to make the request – GET, POST, PUT, DELETE — is used to identify the action to invoke. The ASP.NET Web API uses different routing conventions than normal ASP.NET MVC controllers. When you make an HTTP GET request then any API controller method with a name that starts with “GET” is invoked. So, we could have called our API controller action GetPopcorn() instead of GetMovie() and it would still be invoked by the URL api/movie/1. The default route for the Web API is defined in the Global.asax file and it looks like this: routes.MapHttpRoute( name: "DefaultApi", routeTemplate: "api/{controller}/{id}", defaults: new { id = RouteParameter.Optional } ); We can invoke our GetMovie() controller action with the jQuery code in the following HTML page: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Get Movie</title> </head> <body> <div> Title: <span id="title"></span> </div> <div> Director: <span id="director"></span> </div> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> getMovie(1, function (movie) { $("#title").html(movie.Title); $("#director").html(movie.Director); }); function getMovie(id, callback) { $.ajax({ url: "/api/Movie", data: { id: id }, type: "GET", contentType: "application/json;charset=utf-8", statusCode: { 200: function (movie) { callback(movie); }, 404: function () { alert("Not Found!"); } } }); } </script> </body> </html> In the code above, the jQuery $.ajax() method is used to invoke the GetMovie() method. Notice that the Ajax call handles two HTTP response codes. When the GetMove() method successfully returns a movie, the method returns a 200 status code. In that case, the details of the movie are displayed in the HTML page. Otherwise, if the movie is not found, the GetMovie() method returns a 404 status code. In that case, the page simply displays an alert box indicating that the movie was not found (hopefully, you would implement something more graceful in an actual application). You can use your browser’s Developer Tools to see what is going on in the background when you open the HTML page (hit F12 in the most recent version of most browsers). For example, you can use the Network tab in Google Chrome to see the Ajax request which invokes the GetMovie() method: Getting a Set of Records with the ASP.NET Web API Let’s modify our Movie API controller so that it returns a collection of movies. The following Movie controller has a new ListMovies() method which returns a (hard-coded) collection of movies: using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Net.Http; using System.Web.Http; using MyWebAPIApp.Models; namespace MyWebAPIApp.Controllers { public class MovieController : ApiController { public IEnumerable<Movie> ListMovies() { return new List<Movie> { new Movie {Id=1, Title="Star Wars", Director="Lucas"}, new Movie {Id=1, Title="King Kong", Director="Jackson"}, new Movie {Id=1, Title="Memento", Director="Nolan"} }; } } } Because we named our action ListMovies(), the default Web API route will never match it. Therefore, we need to add the following custom route to our Global.asax file (at the top of the RegisterRoutes() method): routes.MapHttpRoute( name: "ActionApi", routeTemplate: "api/{controller}/{action}/{id}", defaults: new { id = RouteParameter.Optional } ); This route enables us to invoke the ListMovies() method with the URL /api/movie/listmovies. Now that we have exposed our collection of movies from the server, we can retrieve and display the list of movies using jQuery in our HTML page: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>List Movies</title> </head> <body> <div id="movies"></div> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> listMovies(function (movies) { var strMovies=""; $.each(movies, function (index, movie) { strMovies += "<div>" + movie.Title + "</div>"; }); $("#movies").html(strMovies); }); function listMovies(callback) { $.ajax({ url: "/api/Movie/ListMovies", data: {}, type: "GET", contentType: "application/json;charset=utf-8", }).then(function(movies){ callback(movies); }); } </script> </body> </html> Inserting a Record with the ASP.NET Web API Now let’s modify our Movie API controller so it supports creating new records: public HttpResponseMessage<Movie> PostMovie(Movie movieToCreate) { // Add movieToCreate to the database and update primary key movieToCreate.Id = 23; // Build a response that contains the location of the new movie var response = new HttpResponseMessage<Movie>(movieToCreate, HttpStatusCode.Created); var relativePath = "/api/movie/" + movieToCreate.Id; response.Headers.Location = new Uri(Request.RequestUri, relativePath); return response; } The PostMovie() method in the code above accepts a movieToCreate parameter. We don’t actually store the new movie anywhere. In real life, you will want to call a service method to store the new movie in a database. When you create a new resource, such as a new movie, you should return the location of the new resource. In the code above, the URL where the new movie can be retrieved is assigned to the Location header returned in the PostMovie() response. Because the name of our method starts with “Post”, we don’t need to create a custom route. The PostMovie() method can be invoked with the URL /Movie/PostMovie – just as long as the method is invoked within the context of a HTTP POST request. The following HTML page invokes the PostMovie() method. <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Create Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> var movieToCreate = { title: "The Hobbit", director: "Jackson" }; createMovie(movieToCreate, function (newMovie) { alert("New movie created with an Id of " + newMovie.Id); }); function createMovie(movieToCreate, callback) { $.ajax({ url: "/api/Movie", data: JSON.stringify( movieToCreate ), type: "POST", contentType: "application/json;charset=utf-8", statusCode: { 201: function (newMovie) { callback(newMovie); } } }); } </script> </body> </html> This page creates a new movie (the Hobbit) by calling the createMovie() method. The page simply displays the Id of the new movie: The HTTP Post operation is performed with the following call to the jQuery $.ajax() method: $.ajax({ url: "/api/Movie", data: JSON.stringify( movieToCreate ), type: "POST", contentType: "application/json;charset=utf-8", statusCode: { 201: function (newMovie) { callback(newMovie); } } }); Notice that the type of Ajax request is a POST request. This is required to match the PostMovie() method. Notice, furthermore, that the new movie is converted into JSON using JSON.stringify(). The JSON.stringify() method takes a JavaScript object and converts it into a JSON string. Finally, notice that success is represented with a 201 status code. The HttpStatusCode.Created value returned from the PostMovie() method returns a 201 status code. Updating a Record with the ASP.NET Web API Here’s how we can modify the Movie API controller to support updating an existing record. In this case, we need to create a PUT method to handle an HTTP PUT request: public void PutMovie(Movie movieToUpdate) { if (movieToUpdate.Id == 1) { // Update the movie in the database return; } // If you can't find the movie to update throw new HttpResponseException(HttpStatusCode.NotFound); } Unlike our PostMovie() method, the PutMovie() method does not return a result. The action either updates the database or, if the movie cannot be found, returns an HTTP Status code of 404. The following HTML page illustrates how you can invoke the PutMovie() method: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Put Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> var movieToUpdate = { id: 1, title: "The Hobbit", director: "Jackson" }; updateMovie(movieToUpdate, function () { alert("Movie updated!"); }); function updateMovie(movieToUpdate, callback) { $.ajax({ url: "/api/Movie", data: JSON.stringify(movieToUpdate), type: "PUT", contentType: "application/json;charset=utf-8", statusCode: { 200: function () { callback(); }, 404: function () { alert("Movie not found!"); } } }); } </script> </body> </html> Deleting a Record with the ASP.NET Web API Here’s the code for deleting a movie: public HttpResponseMessage DeleteMovie(int id) { // Delete the movie from the database // Return status code return new HttpResponseMessage(HttpStatusCode.NoContent); } This method simply deletes the movie (well, not really, but pretend that it does) and returns a No Content status code (204). The following page illustrates how you can invoke the DeleteMovie() action: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Delete Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> deleteMovie(1, function () { alert("Movie deleted!"); }); function deleteMovie(id, callback) { $.ajax({ url: "/api/Movie", data: JSON.stringify({id:id}), type: "DELETE", contentType: "application/json;charset=utf-8", statusCode: { 204: function () { callback(); } } }); } </script> </body> </html> Performing Validation How do you perform form validation when using the ASP.NET Web API? Because validation in ASP.NET MVC is driven by the Default Model Binder, and because the Web API uses the Default Model Binder, you get validation for free. Let’s modify our Movie class so it includes some of the standard validation attributes: using System.ComponentModel.DataAnnotations; namespace MyWebAPIApp.Models { public class Movie { public int Id { get; set; } [Required(ErrorMessage="Title is required!")] [StringLength(5, ErrorMessage="Title cannot be more than 5 characters!")] public string Title { get; set; } [Required(ErrorMessage="Director is required!")] public string Director { get; set; } } } In the code above, the Required validation attribute is used to make both the Title and Director properties required. The StringLength attribute is used to require the length of the movie title to be no more than 5 characters. Now let’s modify our PostMovie() action to validate a movie before adding the movie to the database: public HttpResponseMessage PostMovie(Movie movieToCreate) { // Validate movie if (!ModelState.IsValid) { var errors = new JsonArray(); foreach (var prop in ModelState.Values) { if (prop.Errors.Any()) { errors.Add(prop.Errors.First().ErrorMessage); } } return new HttpResponseMessage<JsonValue>(errors, HttpStatusCode.BadRequest); } // Add movieToCreate to the database and update primary key movieToCreate.Id = 23; // Build a response that contains the location of the new movie var response = new HttpResponseMessage<Movie>(movieToCreate, HttpStatusCode.Created); var relativePath = "/api/movie/" + movieToCreate.Id; response.Headers.Location = new Uri(Request.RequestUri, relativePath); return response; } If ModelState.IsValid has the value false then the errors in model state are copied to a new JSON array. Each property – such as the Title and Director property — can have multiple errors. In the code above, only the first error message is copied over. The JSON array is returned with a Bad Request status code (400 status code). The following HTML page illustrates how you can invoke our modified PostMovie() action and display any error messages: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Create Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> var movieToCreate = { title: "The Hobbit", director: "" }; createMovie(movieToCreate, function (newMovie) { alert("New movie created with an Id of " + newMovie.Id); }, function (errors) { var strErrors = ""; $.each(errors, function(index, err) { strErrors += "*" + err + "n"; }); alert(strErrors); } ); function createMovie(movieToCreate, success, fail) { $.ajax({ url: "/api/Movie", data: JSON.stringify(movieToCreate), type: "POST", contentType: "application/json;charset=utf-8", statusCode: { 201: function (newMovie) { success(newMovie); }, 400: function (xhr) { var errors = JSON.parse(xhr.responseText); fail(errors); } } }); } </script> </body> </html> The createMovie() function performs an Ajax request and handles either a 201 or a 400 status code from the response. If a 201 status code is returned then there were no validation errors and the new movie was created. If, on the other hand, a 400 status code is returned then there was a validation error. The validation errors are retrieved from the XmlHttpRequest responseText property. The error messages are displayed in an alert: (Please don’t use JavaScript alert dialogs to display validation errors, I just did it this way out of pure laziness) This validation code in our PostMovie() method is pretty generic. There is nothing specific about this code to the PostMovie() method. In the following video, Jon Galloway demonstrates how to create a global Validation filter which can be used with any API controller action: http://www.asp.net/web-api/overview/web-api-routing-and-actions/video-custom-validation His validation filter looks like this: using System.Json; using System.Linq; using System.Net; using System.Net.Http; using System.Web.Http.Controllers; using System.Web.Http.Filters; namespace MyWebAPIApp.Filters { public class ValidationActionFilter:ActionFilterAttribute { public override void OnActionExecuting(HttpActionContext actionContext) { var modelState = actionContext.ModelState; if (!modelState.IsValid) { dynamic errors = new JsonObject(); foreach (var key in modelState.Keys) { var state = modelState[key]; if (state.Errors.Any()) { errors[key] = state.Errors.First().ErrorMessage; } } actionContext.Response = new HttpResponseMessage<JsonValue>(errors, HttpStatusCode.BadRequest); } } } } And you can register the validation filter in the Application_Start() method in the Global.asax file like this: GlobalConfiguration.Configuration.Filters.Add(new ValidationActionFilter()); After you register the Validation filter, validation error messages are returned from any API controller action method automatically when validation fails. You don’t need to add any special logic to any of your API controller actions to take advantage of the filter. Querying using OData The OData protocol is an open protocol created by Microsoft which enables you to perform queries over the web. The official website for OData is located here: http://odata.org For example, here are some of the query options which you can use with OData: · $orderby – Enables you to retrieve results in a certain order. · $top – Enables you to retrieve a certain number of results. · $skip – Enables you to skip over a certain number of results (use with $top for paging). · $filter – Enables you to filter the results returned. The ASP.NET Web API supports a subset of the OData protocol. You can use all of the query options listed above when interacting with an API controller. The only requirement is that the API controller action returns its data as IQueryable. For example, the following Movie controller has an action named GetMovies() which returns an IQueryable of movies: public IQueryable<Movie> GetMovies() { return new List<Movie> { new Movie {Id=1, Title="Star Wars", Director="Lucas"}, new Movie {Id=2, Title="King Kong", Director="Jackson"}, new Movie {Id=3, Title="Willow", Director="Lucas"}, new Movie {Id=4, Title="Shrek", Director="Smith"}, new Movie {Id=5, Title="Memento", Director="Nolan"} }.AsQueryable(); } If you enter the following URL in your browser: /api/movie?$top=2&$orderby=Title Then you will limit the movies returned to the top 2 in order of the movie Title. You will get the following results: By using the $top option in combination with the $skip option, you can enable client-side paging. For example, you can use $top and $skip to page through thousands of products, 10 products at a time. The $filter query option is very powerful. You can use this option to filter the results from a query. Here are some examples: Return every movie directed by Lucas: /api/movie?$filter=Director eq ‘Lucas’ Return every movie which has a title which starts with ‘S’: /api/movie?$filter=startswith(Title,’S') Return every movie which has an Id greater than 2: /api/movie?$filter=Id gt 2 The complete documentation for the $filter option is located here: http://www.odata.org/developers/protocols/uri-conventions#FilterSystemQueryOption Summary The goal of this blog entry was to provide you with an overview of the new ASP.NET Web API introduced with the Beta release of ASP.NET 4. In this post, I discussed how you can retrieve, insert, update, and delete data by using jQuery with the Web API. I also discussed how you can use the standard validation attributes with the Web API. You learned how to return validation error messages to the client and display the error messages using jQuery. Finally, we briefly discussed how the ASP.NET Web API supports the OData protocol. For example, you learned how to filter records returned from an API controller action by using the $filter query option. I’m excited about the new Web API. This is a feature which I expect to use with almost every ASP.NET application which I build in the future.

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Oracle Support Master Note for Troubleshooting Advanced Queuing and Oracle Streams Propagation Issues (Doc ID 233099.1)

- by faye.todd(at)oracle.com

Master Note for Troubleshooting Advanced Queuing and Oracle Streams Propagation Issues (Doc ID 233099.1) Copyright (c) 2010, Oracle Corporation. All Rights Reserved. In this Document Purpose Last Review Date Instructions for the Reader Troubleshooting Details 1. Scope and Application 2. Definitions and Classifications 3. How to Use This Guide 4. Basic AQ Propagation Troubleshooting 5. Additional Troubleshooting Steps for AQ Propagation of User-Enqueued and Dequeued Messages 6. Additional Troubleshooting Steps for Propagation in an Oracle Streams Environment 7. Performance Issues References Applies to: Oracle Server - Enterprise Edition - Version: 8.1.7.0 to 11.2.0.2 - Release: 8.1.7 to 11.2Information in this document applies to any platform. Purpose This document presents a step-by-step methodology for troubleshooting and resolving problems with Advanced Queuing Propagation in both Streams and basic Advanced Queuing environments. It also serves as a master reference for other more specific notes on Oracle Streams Propagation and Advanced Queuing Propagation issues. Last Review Date December 20, 2010 Instructions for the Reader A Troubleshooting Guide is provided to assist in debugging a specific issue. When possible, diagnostic tools are included in the document to assist in troubleshooting. Troubleshooting Details 1. Scope and Application This note is intended for Database Administrators of Oracle databases where issues are being encountered with propagating messages between advanced queues, whether the queues are used for user-created messaging systems or for Oracle Streams. It contains troubleshooting steps and links to notes for further problem resolution.It can also be used a template to document a problem when it is necessary to engage Oracle Support Services. Knowing what is NOT happening can frequently speed up the resolution process by focusing solely on the pertinent problem area. This guide is divided into five parts: Section 2: Definitions and Classifications (discusses the different types and features of propagations possible - helpful for understanding the rest of the guide) Section 3: How to Use this Guide (to be used as a start part for determining the scope of the problem and what sections to consult) Section 4. Basic AQ propagation troubleshooting (applies to both AQ propagation of user enqueued and dequeued messages as well as Oracle Streams propagations) Section 5. Additional troubleshooting steps for AQ propagation of user enqueued and dequeued messages Section 6. Additional troubleshooting steps for Oracle Streams propagation Section 7. Performance issues 2. Definitions and Classifications Given the potential scope of issues that can be encountered with AQ propagation, the first recommended step is to do some basic diagnosis to determine the type of problem that is being encountered. 2.1. What Type of Propagation is Being Used? 2.1.1. Buffered Messaging For an advanced queue, messages can be maintained on disk (persistent messaging) or in memory (buffered messaging). To determine if a queue is buffered or not, reference the GV_$BUFFERED_QUEUES view. If the queue does not appear in this view, it is persistent. 2.1.2. Propagation mode - queue-to-dblink vs queue-to-queue As of 10.2, an AQ propagation can also be defined as queue-to-dblink, or queue-to-queue: queue-to-dblink: The propagation delivers messages or events from the source queue to all subscribing queues at the destination database identified by the dblink. A single propagation schedule is used to propagate messages to all subscribing queues. Hence any changes made to this schedule will affect message delivery to all the subscribing queues. This mode does not support multiple propagations from the same source queue to the same target database. queue-to-queue: Added in 10.2, this propagation mode delivers messages or events from the source queue to a specific destination queue identified on the database link. This allows the user to have fine-grained control on the propagation schedule for message delivery. This new propagation mode also supports transparent failover when propagating to a destination Oracle RAC system. With queue-to-queue propagation, you are no longer required to re-point a database link if the owner instance of the queue fails on Oracle RAC. This mode supports multiple propagations to the same target database if the target queues are different. The default is queue-to-dblink. To verify if queue-to-queue propagation is being used, in non-Streams environments query DBA_QUEUE_SCHEDULES.DESTINATION - if a remote queue is listed along with the remote database link, then queue-to-queue propagation is being used. For Streams environments, the DBA_PROPAGATION.QUEUE_TO_QUEUE column can be checked.See the following note for a method to switch between the two modes:Document 827473.1 How to alter propagation from queue-to-queue to queue-to-dblink 2.1.3. Combined Capture and Apply (CCA) for Streams In 11g Oracle Streams environments, an optimization called Combined Capture and Apply (CCA) is implemented by default when possible. Although a propagation is configured in this case, Streams does not use it; instead it passes information directly from capture to an apply receiver. To see if CCA is in use: COLUMN CAPTURE_NAME HEADING 'Capture Name' FORMAT A30COLUMN OPTIMIZATION HEADING 'CCA Mode?' FORMAT A10SELECT CAPTURE_NAME, DECODE(OPTIMIZATION,0, 'No','Yes') OPTIMIZATIONFROM V$STREAMS_CAPTURE; Also, see the following note:Document 463820.1 Streams Combined Capture and Apply in 11g 2.2. Queue Table Compatibility There are three types of queue table compatibility. In more recent databases, queue tables may be present in all three modes of compatibility: 8.0 - earliest version, deprecated in 10.2 onwards 8.1 - support added for RAC, asynchronous notification, secure queues, queue level access control, rule-based subscribers, separate storage of history information 10.0 - if the database is in 10.1-compatible mode, then the default value for queue table compatibility is 10.0 2.3. Single vs Multiple Consumer Queue Tables If more than one recipient can dequeue a message from a queue, then its queue table is multiple consumer. You can propagate messages from a multiple-consumer queue to a single-consumer queue. Propagation from a single-consumer queue to a multiple-consumer queue is not possible. 3. How to Use This Guide 3.1. Are Messages Being Propagated at All, or is the Propagation Just Slow? Run the following query on the source database for the propagation (assuming that it is running): select TOTAL_NUMBER from DBA_QUEUE_SCHEDULES where QNAME='<source_queue_name>'; If TOTAL_NUMBER is increasing, then propagation is most likely functioning, although it may be slow. For performance issues, see Section 7. 3.2. Propagation Between Persistent User-Created Queues See Sections 4 and 5 (and optionally Section 6 if performance is an issue). 3.3. Propagation Between Buffered User-Created Queues See Sections 4, 5, and 6 (and optionally Section 7 if performance is an issue). 3.4. Propagation between Oracle Streams Queues (without Combined Capture and Apply (CCA) Optimization) See Sections 4 and 6 (and optionally Section 7 if performance is an issue). 3.5. Propagation between Oracle Streams Queues (with Combined Capture and Apply (CCA) Optimization) Although an AQ propagation is not used directly in this case, some characteristics of the message transfer are inferred from the propagation parameters used. Some parts of Sections 4 and 6 still apply. 3.6. Messaging Gateway Propagations This note does not apply to Messaging Gateway propagations. 4. Basic AQ Propagation Troubleshooting 4.1. Double-check Your Code Make sure that you are consistent in your usage of the database link(s) names, queue names, etc. It may be useful to plot a diagram of which queues are connected via which database links to make sure that the logical structure is correct. 4.2. Verify that Job Queue Processes are Running 4.2.1. Versions 10.2 and Lower - DBA_JOBS Package For versions 10.2 and lower, a scheduled propagation is managed by DBMS_JOB package. The propagation is performed by job queue process background processes. Therefore we need to verify that there are sufficient processes available for the propagation process. We should have at least 4 job queue processes running and preferably more depending on the number of other jobs running in the database. It should be noted that for AQ specific work, AQ will only ever use half of the job queue processes available.An issue caused by an inadequate job queue processes parameter setting is described in the following note:Document 298015.1 Kwqjswproc:Excep After Loop: Assigning To Self 4.2.1.1. Job Queue Processes in Initalization Parameter File The parameter JOB_QUEUE_PROCESSES in the init.ora/spfile should be > 0. The value can be changed dynamically via connect / as sysdbaalter system set JOB_QUEUE_PROCESSES=10; 4.2.1.2. Job Queue Processes in Memory The following command will show how many job queue processes are currentlyin use by this instance (this may be different than what is in the init.ora/spfile): connect / as sysdbashow parameter job; 4.2.1.3. OS PIDs Corresponding to Job Queue Processes Identify the operating system process ids (spids) of job queue processes involved in propagation via select p.SPID, p.PROGRAM from V$PROCESS p, DBA_JOBS_RUNNING jr, V$SESSION s, DBA_JOBS j where s.SID=jr.SID and s.PADDR=p.ADDR and jr.JOB=j.JOBand j.WHAT like '%sys.dbms_aqadm.aq$_propaq(job)%'; and these SPIDs can be used to check at the operating system level that they exist.In 8i a job queue process will have a name similar to: ora_snp1_<instance_name>.In 9i onwards you will see a coordinator process: ora_cjq0_ and multiple slave processes: ora_jnnn_<instance_name>, where nnn is an integer between 1 and 999. 4.2.2. Version 11.1 and Above - Oracle Scheduler In version 11.1 and above, Oracle Scheduler is used to perform AQ and Streams propagations. Oracle Scheduler automatically tunes the number of slave processes for these jobs based on the load on the computer system, and the JOB_QUEUE_PROCESSES initialization parameter is only used to specify the maximum number of slave processes. Therefore, the JOB_QUEUE_PROCESSES initialization parameter does not need to be set (it defaults to a very high number), unless you want to limit the number of slaves that can be created. If JOB_QUEUE_PROCESSES = 0, no propagation jobs will run.See the following note for a discussion of Oracle Streams 11g and Oracle Scheduler:Document 1083608.1 11g Streams and Oracle Scheduler 4.2.2.1. Job Queue Processes in Initalization Parameter File The parameter JOB_QUEUE_PROCESSES in the init.ora/spfile should be > 0, and preferably be left at its default value. The value can be changed dynamically via connect / as sysdbaalter system set JOB_QUEUE_PROCESSES=10; To set the JOB_QUEUE_PROCESSES parameter to its default value, run: connect / as sysdbaalter system reset JOB_QUEUE_PROCESSES; and then bounce the instance. 4.2.2.2. Job Queue Processes in Memory The following command will show how many job queue processes are currently in use by this instance (this may be different than what is in the init.ora/spfile): connect / as sysdbashow parameter job; 4.2.2.3. OS PIDs Corresponding to Job Queue Processes Identify the operating system process ids (SPIDs) of job queue processes involved in propagation via col PROGRAM for a30select p.SPID, p.PROGRAM, j.JOB_namefrom v$PROCESS p, DBA_SCHEDULER_RUNNING_JOBS jr, V$SESSION s, DBA_SCHEDULER_JOBS j where s.SID=jr.SESSION_ID and s.PADDR=p.ADDRand jr.JOB_name=j.JOB_NAME and j.JOB_NAME like '%AQ_JOB$_%'; and these SPIDs can be used to check at the operating system level that they exist.You will see a coordinator process: ora_cjq0_ and multiple slave processes: ora_jnnn_<instance_name>, where nnn is an integer between 1 and 999. 4.3. Check the Alert Log and Any Associated Trace Files The first place to check for propagation failures is the alert logs at all sites (local and if relevant all remote sites). When a job queue process attempts to execute a schedule and fails it will always write an error stack to the alert log. This error stack will also be written in a job queue process trace file, which will be written to the BACKGROUND_DUMP_DEST location for 10.2 and below, and in the DIAGNOSTIC_DEST location for 11g. The fact that errors are written to the alert log demonstrates that the schedule is executing. This means that the problem could be with the set up of the schedule. In this example the ORA-02068 demonstrates that the failure was at the remote site. Further investigation revealed that the remote database was not open, hence the ORA-03114 error. Starting the database resolved the problem. Thu Feb 14 10:40:05 2002 Propagation Schedule for (AQADM.MULTIPLEQ, SHANE816.WORLD) encountered following error:ORA-04052: error occurred when looking up Remote object [email protected]: error occurred at recursive SQL level 4ORA-02068: following severe error from SHANE816ORA-03114: not connected to ORACLEORA-06512: at "SYS.DBMS_AQADM_SYS", line 4770ORA-06512: at "SYS.DBMS_AQADM", line 548ORA-06512: at line 1 Other potential errors that may be written to the alert log can be found in the following notes:Document 827184.1 AQ Propagation with CLOB data types Fails with ORA-22990 (11.1)Document 846297.1 AQ Propagation Fails : ORA-00600[kope2upic2954] or Ora-00600[Kghsstream_copyn] (10.2, 11.1)Document 731292.1 ORA-25215 Reported on Local Propagation When Using Transformation with ANYDATA queue tables (10.2, 11.1, 11.2)Document 365093.1 ORA-07445 [kwqppay2aqe()+7360] Reported on Propagation of a Transformed Message (10.1, 10.2)Document 219416.1 Advanced Queuing Propagation Fails with ORA-22922 (9.0)Document 1203544.1 AQ Propagation Aborted with ORA-600 [ociksin: invalid status] on SYS.DBMS_AQADM_SYS.AQ$_PROPAGATION_PROCEDURE After Upgrade (11.1, 11.2)Document 1087324.1 ORA-01405 ORA-01422 reported by Advanced Queuing Propagation schedules after RAC reconfiguration (10.2)Document 1079577.1 Advanced Queuing Propagation Fails With "ORA-22370 incorrect usage of method" (9.2, 10.2, 11.1, 11.2)Document 332792.1 ORA-04061 error relating to SYS.DBMS_PRVTAQIP reported when setting up Statspack (8.1, 9.0, 9.2, 10.1)Document 353325.1 ORA-24056: Internal inconsistency for QUEUE <queue_name> and destination <dblink> (8.1, 9.0, 9.2, 10.1, 10.2, 11.1, 11.2)Document 787367.1 ORA-22275 reported on Propagating Messages with LOB component when propagating between 10.1 and 10.2 (10.1, 10.2)Document 566622.1 ORA-22275 when propagating >4K AQ$_JMS_TEXT_MESSAGEs from 9.2.0.8 to 10.2.0.1 (9.2, 10.1)Document 731539.1 ORA-29268: HTTP client error 401 Unauthorized Error when the AQ Servlet attempts to Propagate a message via HTTP (9.0, 9.2, 10.1, 10.2, 11.1)Document 253131.1 Concurrent Writes May Corrupt LOB Segment When Using Auto Segment Space Management (ORA-1555) (9.2)Document 118884.1 How to unschedule a propagation schedule stuck in pending stateDocument 222992.1 DBMS_AQADM.DISABLE_PROPAGATION_SCHEDULE Returns ORA-24082Document 282987.1 Propagated Messages marked UNDELIVERABLE after Drop and Recreate Of Remote QueueDocument 1204080.1 AQ Propagation Failing With ORA-25329 After Upgraded From 8i or 9i to 10g or 11g.Document 1233675.1 AQ Propagation stops after upgrade to 11.2.0.1 ORA-30757 4.3.1. Errors Related to Incorrect Network Configuration The most common propagation errors result from an incorrect network configuration. The list below contains common errors caused by tnsnames.ora file or database links being configured incorrectly: - ORA-12154: TNS:could not resolve service name- ORA-12505: TNS:listener does not currently know of SID given in connect descriptor- ORA-12514: TNS:listener could not resolve SERVICE_NAME - ORA-12541: TNS-12541 TNS:no listener 4.4. Check the Database Links Exist and are Functioning Correctly For schedules to remote databases confirm the database link exists via. SQL> col DBLINK for a45SQL> select QNAME, NVL(REGEXP_SUBSTR(DESTINATION, '[^@]+', 1, 2), DESTINATION) dblink2 from DBA_QUEUE_SCHEDULES3 where MESSAGE_DELIVERY_MODE = 'PERSISTENT';QNAME DBLINK------------------------------ ---------------------------------------------MY_QUEUE ORCL102B.WORLD Connect as the owner of the link and select across it to verify it works and connects to the database we expect. i.e. select * from ALL_QUEUES@ ORCL102B.WORLD; You need to ensure that the userid that scheduled the propagation (using DBMS_AQADM.SCHEDULE_PROPAGATION or DBMS_PROPAGATION_ADM.CREATE_PROPAGATION if using Streams) has access to the database link for the destination. 4.5. Has Propagation Been Correctly Scheduled? Check that the propagation schedule has been created and that a job queue process has been assigned. Look for the entry in DBA_QUEUE_SCHEDULES and SYS.AQ$_SCHEDULES for your schedule. For 10g and below, check that it has a JOBNO entry in SYS.AQ$_SCHEDULES, and that there is an entry in DBA_JOBS with that JOBNO. For 11g and above, check that the schedule has a JOB_NAME entry in SYS.AQ$_SCHEDULES, and that there is an entry in DBA_SCHEDULER_JOBS with that JOB_NAME. Check the destination is as intended and spelled correctly. SQL> select SCHEMA, QNAME, DESTINATION, SCHEDULE_DISABLED, PROCESS_NAME from DBA_QUEUE_SCHEDULES;SCHEMA QNAME DESTINATION S PROCESS------- ---------- ------------------ - -----------AQADM MULTIPLEQ AQ$_LOCAL N J000 AQ$_LOCAL in the destination column shows that the queue to which we are propagating to is in the same database as the source queue. If the propagation was to a remote (different) database, a database link will be in the DESTINATION column. The entry in the SCHEDULE_DISABLED column, N, means that the schedule is NOT disabled. If Y (yes) appears in this column, propagation is disabled and the schedule will not be executed. If not using Oracle Streams, propagation should resume once you have enabled the schedule by invoking DBMS_AQADM.ENABLE_PROPAGATION_SCHEDULE (for 10.2 Oracle Streams and above, the DBMS_PROPAGATION_ADM.START_PROPAGATION procedure should be used). The PROCESS_NAME is the name of the job queue process currently allocated to execute the schedule. This process is allocated dynamically at execution time. If the PROCESS_NAME column is null (empty) the schedule is not currently executing. You may need to execute this statement a number of times to verify if a process is being allocated. If a process is at some time allocated to the schedule, it is attempting to execute. SQL> select SCHEMA, QNAME, LAST_RUN_DATE, NEXT_RUN_DATE from DBA_QUEUE_SCHEDULES;SCHEMA QNAME LAST_RUN_DATE NEXT_RUN_DATE------ ----- ----------------------- ----------------------- AQADM MULTIPLEQ 13-FEB-2002 13:18:57 13-FEB-2002 13:20:30 In 11g, these dates are expressed in TIMESTAMP WITH TIME ZONE datatypes. If the NEXT_RUN_DATE and NEXT_RUN_TIME columns are null when this statement is executed, the scheduled propagation is currently in progress. If they never change it would suggest that the schedule itself is never executing. If the next scheduled execution is too far away, change the NEXT_TIME parameter of the schedule so that schedules are executed more frequently (assuming that the window is not set to be infinite). Parameters of a schedule can be changed using the DBMS_AQADM.ALTER_PROPAGATION_SCHEDULE call. In 10g and below, scheduling propagation posts a job in the DBA_JOBS view. The columns are more or less the same as DBA_QUEUE_SCHEDULES so you just need to recognize the job and verify that it exists. SQL> select JOB, WHAT from DBA_JOBS where WHAT like '%sys.dbms_aqadm.aq$_propaq(job)%';JOB WHAT---- ----------------- 720 next_date := sys.dbms_aqadm.aq$_propaq(job); For 11g, scheduling propagation posts a job in DBA_SCHEDULER_JOBS instead: SQL> select JOB_NAME from DBA_SCHEDULER_JOBS where JOB_NAME like 'AQ_JOB$_%';JOB_NAME------------------------------AQ_JOB$_41 If no job exists, check DBA_QUEUE_SCHEDULES to make sure that the schedule has not been disabled. For 10g and below, the job number is dynamic for AQ propagation schedules. The procedure that is executed to expedite a propagation schedule runs, removes itself from DBA_JOBS, and then reposts a new job for the next scheduled propagation. The job number should therefore always increment unless the schedule has been set up to run indefinitely. 4.6. Is the Schedule Executing but Failing to Complete? Run the following query: SQL> select FAILURES, LAST_ERROR_MSG from DBA_QUEUE_SCHEDULES;FAILURES LAST_ERROR_MSG------------ -----------------------1 ORA-25207: enqueue failed, queue AQADM.INQ is disabled from enqueueingORA-02063: preceding line from SHANE816 The failures column shows how many times we have attempted to execute the schedule and failed. Oracle will attempt to execute the schedule 16 times after which it will be removed from the DBA_JOBS or DBA_SCHEDULER_JOBS view and the schedule will become disabled. The column DBA_QUEUE_SCHEDULES.SCHEDULE_DISABLED will show 'Y'. For 11g and above, the DBA_SCHEDULER_JOBS.STATE column will show 'BROKEN' for the job corresponding to DBA_QUEUE_SCHEDULES.JOB_NAME. Prior to 10g the back off algorithm for failures was exponential, whereas from 10g onwards it is linear. The propagation will become disabled on the 17th attempt. Only the last execution failure will be reflected in the LAST_ERROR_MSG column. That is, if the schedule fails 5 times for 5 different reasons, only the last set of errors will be recorded in DBA_QUEUE_SCHEDULES. Any errors need to be resolved to allow propagation to continue. If propagation has also become disabled due to 17 failures, first resolve the reason for the error and then re-enable the schedule using the DBMS_AQADM.ENABLE_PROPAGATION_SCHEDULE procedure, or DBMS_PROPAGATION_ADM.START_PROPAGATION if using 10.2 or above Oracle Streams. As soon as the schedule executes successfully the error message entries will be deleted. Oracle does not keep a history of past failures. However, when using Oracle Streams, the errors will be retained in the DBA_PROPAGATION view even after the schedule resumes successfully. See the following note for instructions on how to clear out the errors from the DBA_PROPAGATION view:Document 808136.1 How to clear the old errors from DBA_PROPAGATION view?If a schedule is active and no errors are being reported then the source queue may not have any messages to be propagated. 4.7. Do the Propagation Notification Queue Table and Queue Exist? Check to see that the propagation notification queue table and queue exist and are enabled for enqueue and dequeue. Propagation makes use of the propagation notification queue for handling propagation run-time events, and the messages in this queue are stored in a SYS-owned queue table. This queue should never be stopped or dropped and the corresponding queue table never be dropped. 10g and belowThe propagation notification queue table is of the format SYS.AQ$_PROP_TABLE_n, where 'n' is the RAC instance number, i.e. '1' for a non-RAC environment. This queue and queue table are created implicitly when propagation is first scheduled. If propagation has been scheduled and these objects do not exist, try unscheduling and rescheduling propagation. If they still do not exist contact Oracle Support. SQL> select QUEUE_TABLE from DBA_QUEUE_TABLES2 where QUEUE_TABLE like '%PROP_TABLE%' and OWNER = 'SYS';QUEUE_TABLE------------------------------AQ$_PROP_TABLE_1SQL> select NAME, ENQUEUE_ENABLED, DEQUEUE_ENABLED2 from DBA_QUEUES where owner='SYS'3 and QUEUE_TABLE like '%PROP_TABLE%';NAME ENQUEUE DEQUEUE------------------------------ ------- -------AQ$_PROP_NOTIFY_1 YES YESAQ$_AQ$_PROP_TABLE_1_E NO NO If the AQ$_PROP_NOTIFY_1 queue is not enabled for enqueue or dequeue, it should be so enabled using DBMS_AQADM.START_QUEUE. However, the exception queue AQ$_AQ$_PROP_TABLE_1_E should not be enabled for enqueue or dequeue.11g and aboveThe propagation notification queue table is of the format SYS.AQ_PROP_TABLE, and is created when the database is created. If they do not exist, contact Oracle Support. SQL> select QUEUE_TABLE from DBA_QUEUE_TABLES2 where QUEUE_TABLE like '%PROP_TABLE%' and OWNER = 'SYS';QUEUE_TABLE------------------------------AQ_PROP_TABLESQL> select NAME, ENQUEUE_ENABLED, DEQUEUE_ENABLED2 from DBA_QUEUES where owner='SYS'3 and QUEUE_TABLE like '%PROP_TABLE%';NAME ENQUEUE DEQUEUE------------------------------ ------- -------AQ_PROP_NOTIFY YES YESAQ$_AQ_PROP_TABLE_E NO NO If the AQ_PROP_NOTIFY queue is not enabled for enqueue or dequeue, it should be so enabled using DBMS_AQADM.START_QUEUE. However, the exception queue AQ$_AQ$_PROP_TABLE_E should not be enabled for enqueue or dequeue. 4.8. Does the Remote Queue Exist and is it Enabled for Enqueueing? Check that the remote queue the propagation is transferring messages to exists and is enabled for enqueue: SQL> select DESTINATION from USER_QUEUE_SCHEDULES where QNAME = 'OUTQ';DESTINATION-----------------------------------------------------------------------------"AQADM"."INQ"@M2V102.ESSQL> select OWNER, NAME, ENQUEUE_ENABLED, DEQUEUE_ENABLED from [email protected];OWNER NAME ENQUEUE DEQUEUE-------- ------ ----------- -----------AQADM INQ YES YES 4.9. Do the Target and Source Database Charactersets Differ? If a message fails to propagate, check the database charactersets of the source and target databases. Investigate whether the same message can propagate between the databases with the same characterset or it is only a particular combination of charactersets which causes a problem. 4.10. Check the Queue Table Type Agreement Propagation is not possible between queue tables which have types that differ in some respect. One way to determine if this is the case is to run the DBMS_AQADM.VERIFY_QUEUE_TYPES procedure for the two queues that the propagation operates on. If the types do not agree, DBMS_AQADM.VERIFY_QUEUE_TYPES will return '0'.For AQ propagation between databases which have different NLS_LENGTH_SEMANTICS settings, propagation will not work, unless the queues are Oracle Streams ANYDATA queues.See the following notes for issues caused by lack of type agreement:Document 1079577.1 Advanced Queuing Propagation Fails With "ORA-22370: incorrect usage of method"Document 282987.1 Propagated Messages marked UNDELIVERABLE after Drop and Recreate Of Remote QueueDocument 353754.1 Streams Messaging Propagation Fails between Single and Multi-byte Charactersets when using Chararacter Length Semantics in the ADT 4.11. Enable Propagation Tracing 4.11.1. System Level This is set it in the init.ora/spfile as follows: event="24040 trace name context forever, level 10" and restart the instanceThis event cannot be set dynamically with an alter system command until version 10.2: SQL> alter system set events '24040 trace name context forever, level 10'; To unset the event: SQL> alter system set events '24040 trace name context off'; Debugging information will be logged to job queue trace file(s) (jnnn) as propagation takes place. You can check the trace file for errors, and for statements indicating that messages have been sent. For the most part the trace information is understandable. This trace should also be uploaded to Oracle Support if a service request is created. 4.11.2. Attaching to a Specific Process We can also attach to an existing job queue processes that is running a propagation schedule and trace it individually using the oradebug utility, as follows:10.2 and below connect / as sysdbaselect p.SPID, p.PROGRAM from v$PROCESS p, DBA_JOBS_RUNNING jr, V$SESSION s, DBA_JOBS j where s.SID=jr.SID and s.PADDR=p.ADDR and jr.JOB=j.JOB and j.WHAT like '%sys.dbms_aqadm.aq$_propaq(job)%';-- For the process id (SPID) attach to it via oradebug and generate the following traceoradebug setospid <SPID>oradebug unlimitoradebug Event 10046 trace name context forever, level 12oradebug Event 24040 trace name context forever, level 10-- Trace the process for 5 minutesoradebug Event 10046 trace name context offoradebug Event 24040 trace name context off-- The following command returns the pathname/filename to the file being written tooradebug tracefile_name 11g connect / as sysdbacol PROGRAM for a30select p.SPID, p.PROGRAM, j.JOB_NAMEfrom v$PROCESS p, DBA_SCHEDULER_RUNNING_JOBS jr, V$SESSION s, DBA_SCHEDULER_JOBS j where s.SID=jr.SESSION_ID and s.PADDR=p.ADDR and jr.JOB_NAME=j.JOB_NAME and j.JOB_NAME like '%AQ_JOB$_%';-- For the process id (SPID) attach to it via oradebug and generate the following traceoradebug setospid <SPID>oradebug unlimitoradebug Event 10046 trace name context forever, level 12oradebug Event 24040 trace name context forever, level 10-- Trace the process for 5 minutesoradebug Event 10046 trace name context offoradebug Event 24040 trace name context off-- The following command returns the pathname/filename to the file being written tooradebug tracefile_name 4.11.3. Further Tracing The previous tracing steps only trace the job queue process executing the propagation on the source. At times it is useful to trace the propagation receiver process (the session which is enqueueing the messages into the target queue) on the target database which is associated with the job queue process on the source database.These following queries provide ways of identifying the processes involved in propagation so that you can attach to them via oradebug to generate trace information.In order to identify the propagation receiver process you need to execute the query as a user with privileges to access the v$ views in both the local and remote databases so the database link must connect as a user with those privileges in the remote database. The <DBLINK> in the queries should be replaced by the appropriate database link.The queries have two forms due to the differences between operating systems. The value returned by 'Rem Process' is the operating system identifier of the propagation receiver on the remote database. Once identified, this process can be attached to and traced on the remote database using the commands given in Section 4.11.2.10.2 and below - Windows select pl.SPID "JobQ Process", pl.PROGRAM, sr.PROCESS "Rem Process" from v$PROCESS pl, DBA_JOBS_RUNNING jr, V$SESSION s, DBA_JOBS j, V$SESSION@<DBLINK> sr where s.SID=jr.SID and s.PADDR=pl.ADDR and jr.JOB=j.JOB and j.WHAT like '%sys.dbms_aqadm.aq$_propaq(job)%' and pl.SPID=substr(sr.PROCESS, instr(sr.PROCESS,':')+1); 10.2 and below - Unix select pl.SPID "JobQ Process", pl.PROGRAM, sr.PROCESS "Rem Process" from V$PROCESS pl, DBA_JOBS_RUNNING jr, V$SESSION s, DBA_JOBS j, V$SESSION@<DBLINK> sr where s.SID=jr.SID and s.PADDR=pl.ADDR and jr.JOB=j.JOB and j.WHAT like '%sys.dbms_aqadm.aq$_propaq(job)%' and pl.SPID=sr.PROCESS; 11g - Windows select pl.SPID "JobQ Process", pl.PROGRAM, sr.PROCESS "Rem Process" from V$PROCESS pl, DBA_SCHEDULER_RUNNING_JOBS jr, V$SESSION s, DBA_SCHEDULER_JOBS j, V$SESSION@<DBLINK> sr where s.SID=jr.SESSION_ID and s.PADDR=pl.ADDR and jr.JOB_NAME=j.JOB_NAME and j.JOB_NAME like '%AQ_JOB$_%%' and pl.SPID=substr(sr.PROCESS, instr(sr.PROCESS,':')+1); 11g - Unix select pl.SPID "JobQ Process", pl.PROGRAM, sr.PROCESS "Rem Process" from V$PROCESS pl, DBA_SCHEDULER_RUNNING_JOBS jr, V$SESSION s, DBA_SCHEDULER_JOBS j, V$SESSION@<DBLINK> sr where s.SID=jr.SESSION_ID and s.PADDR=pl.ADDR and jr.JOB_NAME=j.JOB_NAME and j.JOB_NAME like '%AQ_JOB$_%%' and pl.SPID=sr.PROCESS; 5. Additional Troubleshooting Steps for AQ Propagation of User-Enqueued and Dequeued Messages 5.1. Check the Privileges of All Users Involved Ensure that the owner of the database link has the necessary privileges on the aq packages. SQL> select TABLE_NAME, PRIVILEGE from USER_TAB_PRIVS;TABLE_NAME PRIVILEGE------------------------------ ----------------------------------------DBMS_LOCK EXECUTEDBMS_AQ EXECUTEDBMS_AQADM EXECUTEDBMS_AQ_BQVIEW EXECUTEQT52814_BUFFER SELECT Note that when queue table is created, a view called QT<nnn>_BUFFER is created in the SYS schema, and the queue table owner is given SELECT privileges on it. The <nnn> corresponds to the object_id of the associated queue table. SQL> select * from USER_ROLE_PRIVS;USERNAME GRANTED_ROLE ADM DEF OS_------------------------------ ------------------------------ ---- ---- ---AQ_USER1 AQ_ADMINISTRATOR_ROLE NO YES NOAQ_USER1 CONNECT NO YES NOAQ_USER1 RESOURCE NO YES NO It is good practice to configure central AQ administrative user. All admin and processing jobs are created, executed and administered as this user. This configuration is not mandatory however, and the database link can be owned by any existing queue user. If this latter configuration is used, ensure that the connecting user has the necessary privileges on the AQ packages and objects involved. Privileges for an AQ Administrative user Execute on DBMS_AQADM Execute on DBMS_AQ Granted the AQ_ADMINISTRATOR_ROLE Privileges for an AQ user Execute on DBMS_AQ Execute on the message payload Enqueue privileges on the remote queue Dequeue privileges on the originating queue Privileges need to be confirmed on both sites when propagation is scheduled to remote destinations. Verify that the user ID used to login to the destination through the database link has been granted privileges to use AQ. 5.2. Verify Queue Payload Types AQ will not propagate messages from one queue to another if the payload types of the two queues are not verified to be equivalent. An AQ administrator can verify if the source and destination's payload types match by executing the DBMS_AQADM.VERIFY_QUEUE_TYPES procedure. The results of the type checking will be stored in the SYS.AQ$_MESSAGE_TYPES table. This table can be accessed using the object identifier OID of the source queue and the address database link of the destination queue, i.e. [schema.]queue_name[@destination]. Prior to Oracle 9i the payload (message type) had to be the same for all the queue tables involved in propagation. From Oracle9i onwards a transformation can be used so that payloads can be converted from one type to another. The following procedural call made on the source database can verify whether we can propagate between the source and the destination queue tables. connect aq_user1/[email protected] serverout onDECLARErc_value number;BEGINDBMS_AQADM.VERIFY_QUEUE_TYPES(src_queue_name => 'AQ_USER1.Q_1', dest_queue_name => 'AQ_USER2.Q_2',destination => 'dbl_aq_user2.es',rc => rc_value);dbms_output.put_line('rc_value code is '||rc_value);END;/ If propagation is possible then the return code value will be 1. If it is 0 then propagation is not possible and further investigation of the types and transformations used by and in conjunction with the queue tables is required. With regard to comparison of the types the following sql can be used to extract the DDL for a specific type with' %' changed appropriately on the source and target. This can then be compared for the source and target. SET LONG 20000 set pagesize 50 EXECUTE DBMS_METADATA.SET_TRANSFORM_PARAM(DBMS_METADATA.SESSION_TRANSFORM, 'STORAGE',false); SELECT DBMS_METADATA.GET_DDL('TYPE',t.type_name) from user_types t WHERE t.type_name like '%'; EXECUTE DBMS_METADATA.SET_TRANSFORM_PARAM(DBMS_METADATA.SESSION_TRANSFORM, 'DEFAULT'); 5.3. Check Message State and Destination The first step in this process is to identify the queue table associated with the problem source queue. Although you schedule propagation for a specific queue, most of the meta-data associated with that queue is stored in the underlying queue table. The following statement finds the queue table for a given queue (note that this is a multiple-consumer queue table). SQL> select QUEUE_TABLE from DBA_QUEUES where NAME = 'MULTIPLEQ';QUEUE_TABLE --------------------MULTIPLEQTABLE For a small amount of messages in a multiple-consumer queue table, the following query can be run: SQL> select MSG_STATE, CONSUMER_NAME, ADDRESS from AQ$MULTIPLEQTABLE where QUEUE = 'MULTIPLEQ';MSG_STATE CONSUMER_NAME ADDRESS-------------- ----------------------- -------------READY AQUSER2 [email protected] AQUSER1READY AQUSER3 AQADM.INQ In this example we see 2 messages ready to be propagated to remote queues and 1 that is not. If the address column is blank, the message is not scheduled for propagation and can only be dequeued from the queue upon which it was enqueued. The MSG_STATE column values are discussed in Document 102330.1 Advanced Queueing MSG_STATE Values and their Interpretation. If the address column has a value, the message has been enqueued for propagation to another queue. The first row in the example includes a database link (@M2V102.ES). This demonstrates that the message should be propagated to a queue at a remote database. The third row does not include a database link so will be propagated to a queue that resides on the same database as the source queue. The consumer name is the intended recipient at the target queue. Note that we are not querying the base queue table directly; rather, we are querying a view that is available on top of every queue table, AQ$<queue_table_name>.A more realistic query in an environment where the queue table contains thousands of messages is8.0.3-compatible multiple-consumer queue table and all compatibility single-consumer queue tables select count(*), MSG_STATE, QUEUE from AQ$<queue_table_name> group by MSG_STATE, QUEUE; 8.1.3 and 10.0-compatible queue tables select count(*), MSG_STATE, QUEUE, CONSUMER_NAME from AQ$<queue_table_name>group by MSG_STATE, QUEUE, CONSUMER_NAME; For multiple-consumer queue tables, if you did not see the expected CONSUMER_NAME , check the syntax of the enqueue code and verify the recipients are declared correctly. If a recipients list is not used on enqueue, check the subscriber list in the AQ$_<queue_table_name>_S view (note that a single-consumer queue table does not have a subscriber view. This view records all members of the default subscription list which were added using the DBMS_AQADM.ADD_SUBSCRIBER procedure and also those enqueued using a recipient list. SQL> select QUEUE, NAME, ADDRESS from AQ$MULTIPLEQTABLE_S;QUEUE NAME ADDRESS---------- ----------- -------------MULTIPLEQ AQUSER2 [email protected] AQUSER1 In this example we have 2 subscribers registered with the queue. We have a local subscriber AQUSER1, and a remote subscriber AQUSER2, on the queue INQ, owned by AQADM, at M2V102.ES. Unless overridden with a recipient list during enqueue every message enqueued to this queue will be propagated to INQ at M2V102.ES.For 8.1 style and above multiple consumer queue tables, you can also check the following information at the target: select CONSUMER_NAME, DEQ_TXN_ID, DEQ_TIME, DEQ_USER_ID, PROPAGATED_MSGID from AQ$<queue_table_name> where QUEUE = '<QUEUE_NAME>'; For 8.0 style queues, if the queue table supports multiple consumers you can obtain the same information from the history column of the queue table: select h.CONSUMER, h.TRANSACTION_ID, h.DEQ_TIME, h.DEQ_USER, h.PROPAGATED_MSGIDfrom AQ$<queue_table_name> t, table(t.history) h where t.Q_NAME = '<QUEUE_NAME>'; A non-NULL TRANSACTION_ID indicates that the message was successfully propagated. Further, the DEQ_TIME indicates the time of propagation, the DEQ_USER indicates the userid used for propagation, and the PROPAGATED_MSGID indicates the message ID of the message that was enqueued at the destination. 6. Additional Troubleshooting Steps for Propagation in an Oracle Streams Environment 6.1. Is the Propagation Enabled? For a propagation job to propagate messages, the propagation must be enabled. For Streams, a special view called DBA_PROPAGATION exists to convey information about Streams propagations. If messages are not being propagated by a propagation as expected, then the propagation might not be enabled. To query for this: SELECT p.PROPAGATION_NAME, DECODE(s.SCHEDULE_DISABLED, 'Y', 'Disabled','N', 'Enabled') SCHEDULE_DISABLED, s.PROCESS_NAME, s.FAILURES, s.LAST_ERROR_MSGFROM DBA_QUEUE_SCHEDULES s, DBA_PROPAGATION pWHERE p.DESTINATION_DBLINK = NVL(REGEXP_SUBSTR(s.DESTINATION, '[^@]+', 1, 2), s.DESTINATION) AND s.SCHEMA = p.SOURCE_QUEUE_OWNER AND s.QNAME = p.SOURCE_QUEUE_NAME AND MESSAGE_DELIVERY_MODE = 'PERSISTENT' order by PROPAGATION_NAME; At times, the propagation job may become "broken" or fail to start after an error has been encountered or after a database restart. If an error is indicated by the above query, an attempt to disable the propagation and then re-enable it can be made. In the examples below, for the propagation named STRMADMIN_PROPAGATE where the queue name is STREAMS_QUEUE owned by STRMADMIN and the destination database link is ORCL2.WORLD, the commands would be:10.2 and above exec dbms_propagation_adm.stop_propagation('STRMADMIN_PROPAGATE'); exec dbms_propagation_adm.start_propagation('STRMADMIN_PROPAGATE'); If the above does not fix the problem, stop the propagation specifying the force parameter (2nd parameter on stop_propagation) as TRUE: exec dbms_propagation_adm.stop_propagation('STRMADMIN_PROPAGATE',true); exec dbms_propagation_adm.start_propagation('STRMADMIN_PROPAGATE'); The statistics for the propagation as well as any old error messages are cleared when the force parameter is set to TRUE. Therefore if the propagation schedule is stopped with FORCE set to TRUE, and upon restart there is still an error message in DBA_PROPAGATION, then the error message is current.9.2 or 10.1 exec dbms_aqadm.disable_propagation_schedule('STRMADMIN.STREAMS_QUEUE','ORCL2.WORLD'); exec dbms.aqadm.enable_propagation_schedule('STRMADMIN.STREAMS_QUEUE','ORCL2.WORLD'); If the above does not fix the problem, perform an unschedule of propagation and then schedule_propagation: exec dbms_aqadm.unschedule_propagation('STRMADMIN.STREAMS_QUEUE','ORCL2.WORLD'); exec dbms_aqadm.schedule_propagation('STRMADMIN.STREAMS_QUEUE','ORCL2.WORLD'); Typically if the error from the first query in Section 6.1 recurs after restarting the propagation as shown above, further troubleshooting of the error is needed. 6.2. Check Propagation Rule Sets and Transformations Inspect the configuration of the rules in the rule set that is associated with the propagation process to make sure that they evaluate to TRUE as expected. If not, then the object or schema will not be propagated. Remember that when a negative rule evaluates to TRUE, the specified object or schema will not be propagated. Finally inspect any rule-based transformations that are implemented with propagation to make sure they are changing the data in the intended way.The following query shows what rule sets are assigned to a propagation: select PROPAGATION_NAME, RULE_SET_OWNER||'.'||RULE_SET_NAME "Positive Rule Set",NEGATIVE_RULE_SET_OWNER||'.'||NEGATIVE_RULE_SET_NAME "Negative Rule Set"from DBA_PROPAGATION; The next two queries list the propagation rules and their conditions. The first is for the positive rule set, the second is for the negative rule set: set long 4000select rsr.RULE_SET_OWNER||'.'||rsr.RULE_SET_NAME RULE_SET ,rsr.RULE_OWNER||'.'||rsr.RULE_NAME RULE_NAME,r.RULE_CONDITION CONDITION fromDBA_RULE_SET_RULES rsr, DBA_RULES rwhere rsr.RULE_NAME = r.RULE_NAME and rsr.RULE_OWNER = r.RULE_OWNER and RULE_SET_NAME in(select RULE_SET_NAME from DBA_PROPAGATION) order by rsr.RULE_SET_OWNER, rsr.RULE_SET_NAME; set long 4000select c.PROPAGATION_NAME, rsr.RULE_SET_OWNER||'.'||rsr.RULE_SET_NAME RULE_SET ,rsr.RULE_OWNER||'.'||rsr.RULE_NAME RULE_NAME,r.RULE_CONDITION CONDITION fromDBA_RULE_SET_RULES rsr, DBA_RULES r ,DBA_PROPAGATION cwhere rsr.RULE_NAME = r.RULE_NAME and rsr.RULE_OWNER = r.RULE_OWNER andrsr.RULE_SET_OWNER=c.NEGATIVE_RULE_SET_OWNER and rsr.RULE_SET_NAME=c.NEGATIVE_RULE_SET_NAMEand rsr.RULE_SET_NAME in(select NEGATIVE_RULE_SET_NAME from DBA_PROPAGATION) order by rsr.RULE_SET_OWNER, rsr.RULE_SET_NAME; 6.3. Determining the Total Number of Messages and Bytes Propagated As in Section 3.1, determining if messages are flowing can be instructive to see whether the propagation is entirely hung or just slow. If the propagation is not in flow control (see Section 6.5.2), but the statistics are incrementing slowly, there may be a performance issue. For Streams implementations two views are available that can assist with this that can show the number of messages sent by a propagation, as well as the number of acknowledgements being returned from the target site: the V$PROPAGATION_SENDER view at the Source site and the V$PROPAGATION_RECEIVER view at the destination site. It is helpful to query both to determine if messages are being delivered to the target. Look for the statistics to increase.Source: select QUEUE_SCHEMA, QUEUE_NAME, DBLINK,HIGH_WATER_MARK, ACKNOWLEDGEMENT, TOTAL_MSGS, TOTAL_BYTESfrom V$PROPAGATION_SENDER; Target: select SRC_QUEUE_SCHEMA, SRC_QUEUE_NAME, SRC_DBNAME, DST_QUEUE_SCHEMA, DST_QUEUE_NAME, HIGH_WATER_MARK, ACKNOWLEDGEMENT, TOTAL_MSGS from V$PROPAGATION_RECEIVER; 6.4. Check Buffered Subscribers The V$BUFFERED_SUBSCRIBERS view displays information about subscribers for all buffered queues in the instance. This view can be queried to make sure that the site that the propagation is propagating to is listed as a subscriber address for the site being propagated from: select QUEUE_SCHEMA, QUEUE_NAME, SUBSCRIBER_ADDRESS from V$BUFFERED_SUBSCRIBERS; The SUBSCRIBER_ADDRESS column will not be populated when the propagation is local (between queues on the same database). 6.5. Common Streams Propagation Errors 6.5.1. ORA-02082: A loopback database link must have a connection qualifier. This error can occur if you use the Streams Setup Wizard in Oracle Enterprise Manager without first configuring the GLOBAL_NAME for your database. 6.5.2. ORA-25307: Enqueue rate too high. Enable flow control DBA_QUEUE_SCHEDULES will display this informational message for propagation when the automatic flow control (10g feature of Streams) has been invoked.Similar to Streams capture processes, a Streams propagation process can also go into a state of 'flow control. This is an informative message that indicates flow control has been automatically enabled to reduce the rate at which messages are being enqueued into at target queue.This typically occurs when the target site is unable to keep up with the rate of messages flowing from the source site. Other than checking that the apply process is running normally on the target site, usually no action is required by the DBA. Propagation and the capture process will be resumed automatically when the target site is able to accept more messages.The following document contains more information:Document 302109.1 Streams Propagation Error: ORA-25307 Enqueue rate too high. Enable flow controlSee the following document for one potential cause of this situation:Document 1097115.1 Oracle Streams Apply Reader is in 'Paused' State 6.5.3. ORA-25315 unsupported configuration for propagation of buffered messages This error typically occurs when the target database is RAC and usually indicates that an attempt was made to propagate buffered messages with the database link pointing to an instance in the destination database which is not the owner instance of the destination queue. To resolve the problem, use queue-to-queue propagation for buffered messages. 6.5.4. ORA-600 [KWQBMCRCPTS101] after dropping / recreating propagation For cause/fixes refer to:Document 421237.1 ORA-600 [KWQBMCRCPTS101] reported by a Qmon slave process after dropping a Streams Propagation 6.5.5. Stopping or Dropping a Streams Propagation Hangs See the following note:Document 1159787.1 Troubleshooting Streams Propagation When It is Not Functioning and Attempts to Stop It Hang 6.6. Streams Propagation-Related Notes for Common Issues Document 437838.1 Streams Specific PatchesDocument 749181.1 How to Recover Streams After Dropping PropagationDocument 368912.1 Queue to Queue Propagation Schedule encountered ORA-12514 in a RAC environmentDocument 564649.1 ORA-02068/ORA-03114/ORA-03113 Errors From Streams Propagation Process - Remote Database is Available and Unschedule/Reschedule Does Not ResolveDocument 553017.1 Stream Propagation Process Errors Ora-4052 Ora-6554 From 11g To 10201Document 944846.1 Streams Propagation Fails Ora-7445 [kohrsmc]Document 745601.1 ORA-23603 'STREAMS enqueue aborted due to low SGA' Error from Streams Propagation, and V$STREAMS_CAPTURE.STATE Hanging on 'Enqueuing Message'Document 333068.1 ORA-23603: Streams Enqueue Aborted Eue To Low SGADocument 363496.1 Ora-25315 Propagating on RAC StreamsDocument 368237.1 Unable to Unschedule Propagation. Streams Queue is InvalidDocument 436332.1 dbms_propagation_adm.stop_propagation hangsDocument 727389.1 Propagation Fails With ORA-12528Document 730911.1 ORA-4063 Is Reported After Dropping Negative Prop.RulesetDocument 460471.1 Propagation Blocked by Qmon Process - Streams_queue_table / 'library cache lock' waitsDocument 1165583.1 ORA-600 [kwqpuspse0-ack] In Streams EnvironmentDocument 1059029.1 Combined Capture and Apply (CCA) : Capture aborts : ORA-1422 after schedule_propagationDocument 556309.1 Changing Propagation/ queue_to_queue : false -> true does does not work; no LCRs propagatedDocument 839568.1 Propagation failing with error: ORA-01536: space quota exceeded for tablespace ''Document 311021.1 Streams Propagation Process : Ora 12154 After Reboot with Transparent Application Failover TAF configuredDocument 359971.1 STREAMS propagation to Primary of physical Standby configuation errors with Ora-01033, Ora-02068Document 1101616.1 DBMS_PROPAGATION_ADM.DROP_PROPAGATION FAILS WITH ORA-1747 7. Performance Issues A propagation may seem to be slow if the queries from Sections 3.1 and 6.3 show that the message statistics are not changing quickly. In Oracle Streams, this more usually is due to a slow apply process at the target rather than a slow propagation. Propagation could be inferred to be slow if the message statistics are changing, and the state of a capture process according to V$STREAMS_CAPTURE.STATE is PAUSED FOR FLOW CONTROL, but an ORA-25307 'Enqueue rate too high. Enable flow control' warning is NOT observed in DBA_QUEUE_SCHEDULES per Section 6.5.2. If this is the case, see the following notes / white papers for suggestions to increase performance:Document 335516.1 Master Note for Streams Performance RecommendationsDocument 730036.1 Overview for Troubleshooting Streams Performance IssuesDocument 780733.1 Streams Propagation Tuning with Network ParametersWhite Paper: http://www.oracle.com/technetwork/database/features/availability/maa-wp-10gr2-streams-performance-130059.pdfWhite Paper: Oracle Streams Configuration Best Practices: Oracle Database 10g Release 10.2, http://www.oracle.com/technetwork/database/features/availability/maa-10gr2-streams-configuration-132039.pdf, See APPENDIX A: USING STREAMS CONFIGURATIONS OVER A NETWORKFor basic AQ propagation, the network tuning in the aforementioned Appendix A of the white paper 'Oracle Streams Configuration Best Practices: Oracle Database 10g Release 10.2' is applicable. References NOTE:102330.1 - Advanced Queueing MSG_STATE Values and their InterpretationNOTE:102771.1 - Advanced Queueing Propagation using PL/SQLNOTE:1059029.1 - Combined Capture and Apply (CCA) : Capture aborts : ORA-1422 after schedule_propagationNOTE:1079577.1 - Advanced Queuing Propagation Fails With "ORA-22370: incorrect usage of method"NOTE:1083608.1 - 11g Streams and Oracle SchedulerNOTE:1087324.1 - ORA-01405 ORA-01422 reported by Adavanced Queueing Propagation schedules after RAC reconfigurationNOTE:1097115.1 - Oracle Streams Apply Reader is in 'Paused' StateNOTE:1101616.1 - DBMS_PROPAGATION_ADM.DROP_PROPAGATION FAILS WITH ORA-1747NOTE:1159787.1 - Troubleshooting Streams Propagation When It is Not Functioning and Attempts to Stop It HangNOTE:1165583.1 - ORA-600 [kwqpuspse0-ack] In Streams EnvironmentNOTE:118884.1 - How to unschedule a propagation schedule stuck in pending stateNOTE:1203544.1 - AQ PROPAGATION ABORTED WITH ORA-600[OCIKSIN: INVALID STATUS] ON SYS.DBMS_AQADM_SYS.AQ$_PROPAGATION_PROCEDURE AFTER UPGRADENOTE:1204080.1 - AQ Propagation Failing With ORA-25329 After Upgraded From 8i or 9i to 10g or 11g.NOTE:219416.1 - Advanced Queuing Propagation fails with ORA-22922NOTE:222992.1 - DBMS_AQADM.DISABLE_PROPAGATION_SCHEDULE Returns ORA-24082NOTE:253131.1 - Concurrent Writes May Corrupt LOB Segment When Using Auto Segment Space Management (ORA-1555)NOTE:282987.1 - Propagated Messages marked UNDELIVERABLE after Drop and Recreate Of Remote QueueNOTE:298015.1 - Kwqjswproc:Excep After Loop: Assigning To SelfNOTE:302109.1 - Streams Propagation Error: ORA-25307 Enqueue rate too high. Enable flow controlNOTE:311021.1 - Streams Propagation Process : Ora 12154 After Reboot with Transparent Application Failover TAF configuredNOTE:332792.1 - ORA-04061 error relating to SYS.DBMS_PRVTAQIP reported when setting up StatspackNOTE:333068.1 - ORA-23603: Streams Enqueue Aborted Eue To Low SGANOTE:335516.1 - Master Note for Streams Performance RecommendationsNOTE:353325.1 - ORA-24056: Internal inconsistency for QUEUE and destination NOTE:353754.1 - Streams Messaging Propagation Fails between Single and Multi-byte Charactersets when using Chararacter Length Semantics in the ADT.NOTE:359971.1 - STREAMS propagation to Primary of physical Standby configuation errors with Ora-01033, Ora-02068NOTE:363496.1 - Ora-25315 Propagating on RAC StreamsNOTE:365093.1 - ORA-07445 [kwqppay2aqe()+7360] reported on Propagation of a Transformed MessageNOTE:368237.1 - Unable to Unschedule Propagation. Streams Queue is InvalidNOTE:368912.1 - Queue to Queue Propagation Schedule encountered ORA-12514 in a RAC environmentNOTE:421237.1 - ORA-600 [KWQBMCRCPTS101] reported by a Qmon slave process after dropping a Streams PropagationNOTE:436332.1 - dbms_propagation_adm.stop_propagation hangsNOTE:437838.1 - Streams Specific PatchesNOTE:460471.1 - Propagation Blocked by Qmon Process - Streams_queue_table / 'library cache lock' waitsNOTE:463820.1 - Streams Combined Capture and Apply in 11gNOTE:553017.1 - Stream Propagation Process Errors Ora-4052 Ora-6554 From 11g To 10201NOTE:556309.1 - Changing Propagation/ queue_to_queue : false -> true does does not work; no LCRs propagatedNOTE:564649.1 - ORA-02068/ORA-03114/ORA-03113 Errors From Streams Propagation Process - Remote Database is Available and Unschedule/Reschedule Does Not ResolveNOTE:566622.1 - ORA-22275 when propagating >4K AQ$_JMS_TEXT_MESSAGEs from 9.2.0.8 to 10.2.0.1NOTE:727389.1 - Propagation Fails With ORA-12528NOTE:730036.1 - Overview for Troubleshooting Streams Performance IssuesNOTE:730911.1 - ORA-4063 Is Reported After Dropping Negative Prop.RulesetNOTE:731292.1 - ORA-25215 Reported On Local Propagation When Using Transformation with ANYDATA queue tablesNOTE:731539.1 - ORA-29268: HTTP client error 401 Unauthorized Error when the AQ Servlet attempts to Propagate a message via HTTPNOTE:745601.1 - ORA-23603 'STREAMS enqueue aborted due to low SGA' Error from Streams Propagation, and V$STREAMS_CAPTURE.STATE Hanging on 'Enqueuing Message'NOTE:749181.1 - How to Recover Streams After Dropping PropagationNOTE:780733.1 - Streams Propagation Tuning with Network ParametersNOTE:787367.1 - ORA-22275 reported on Propagating Messages with LOB component when propagating between 10.1 and 10.2NOTE:808136.1 - How to clear the old errors from DBA_PROPAGATION view ?NOTE:827184.1 - AQ Propagation with CLOB data types Fails with ORA-22990NOTE:827473.1 - How to alter propagation from queue_to_queue to queue_to_dblinkNOTE:839568.1 - Propagation failing with error: ORA-01536: space quota exceeded for tablespace ''NOTE:846297.1 - AQ Propagation Fails : ORA-00600[kope2upic2954] or Ora-00600[Kghsstream_copyn]NOTE:944846.1 - Streams Propagation Fails Ora-7445 [kohrsmc]

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Windows CE Chat Transcript (March 30, 2010)

- by Bruce Eitman

For those of you who missed the chat today, here is the raw transcript. By raw, I mean that I copied and pasted the discussion without any edits. This is divided into two parts, the top part is the answers from the Microsoft Experts and the bottom part is the questions from the audience. Answers from Microsoft: Karel Danihelka [MS] (Expert)[2010-3-30 12:2]: Hi everyone, my name is Karel Danihelka and I am developer in partner response team. Sing Wee [MS] (Expert)[2010-3-30 12:2]: Hi, I'm Sing Wee, part of the CoreOS/BSP Test Team. GLanger_MS (Expert)[2010-3-30 12:2]: Hi, I'm Glen Langer, program manager on the Core Team. Karel Danihelka [MS] (Expert)[2010-3-30 12:3]: Q: I need to implement hardware timers on my windows CE 6.0 device to trigger events at microsecond intervals. Where should i start? A: Until you are using CPU with GHz frequency your only chance is use interrupt handler and implement all funcionality there. But it will be really tricky and may reduce system performance. If period will be near to millisecond timeframe you can use normal thread wait for event pattern. Karel Danihelka [MS] (Expert)[2010-3-30 12:5]: Q: I want to partition my NAND Flash device. One partition to use for hive ragistry and the other for the apps and data. The only way to do it is programmatically or setting some registry values ? A: It need to be set in registry - generally you need mark this partition as boot partition. Karel Danihelka [MS] (Expert)[2010-3-30 12:7]: Q: My CPU is Intel celeron M processor 1Ghz. A: In this case you can try use normal approach - in interrupt handler return SYSINTR and start thread in device driver which will spin thread waiting on event attached to this SYSINTR. Karel Danihelka [MS] (Expert)[2010-3-30 12:7]: Q: If i need to implement it using interrupt handlers, What are all the files that I should look at? A: Good quesiton - I would recommend documentation and there was BSP development book to download for free. mikehall_ms (Moderator)[2010-3-30 12:8]: Q: Hi guys, what's the formal way to report bugs back to the core team / product team? The mechanism of calling the support phone number every time is really onerous and time-consuming. Is there another mechanism? A: Using product support is the formal way to report bugs/issues - Product support can then create an issue that can be tracked. Karel Danihelka [MS] (Expert)[2010-3-30 12:9]: Q: But the operation for creating the partitions ? A: This is tricky - if you will make it autopartition & autoformat it will be created by filesystem. But generally it depends on your boot loader. mikehall_ms (Moderator)[2010-3-30 12:10]: Q: Is Windows Phone 7 related to Windows CE? If so, can you tell me what version of Windows CE is the basis? Is it in fact the new version of Windows Mobile? A: At MIX 2010 Charlie Kindel presented a session that described some of the core technologies that make up Windows Phone 7 Series, including the underlying operating system (Windows CE) and the new ISV programming model based on Silverlight and .NET - check out the Mix Online Videos to get more information. davbo-msft (Moderator)[2010-3-30 12:10]: Q: Is Windows Phone 7 related to Windows CE? If so, can you tell me what version of Windows CE is the basis? Is it in fact the new version of Windows Mobile? A: This forum is to discussed released products in the industry. Windows Mobile & Windows CE are based on the same Windows CE Kernel/system. Windows CE is focused on deliverying the OS for embedded customers in the market where Windows Mobile is focused on deliverying compelling Windows Phone platform. davbo-msft (Moderator)[2010-3-30 12:11]: Q: Is Windows Phone 7 related to Windows CE? If so, can you tell me what version of Windows CE is the basis? Is it in fact the new version of Windows Mobile? A: http://en.wikipedia.org/wiki/Windows_CE Wikipedia gives a good breakdown of the version history. Travis Hobrla [MS] (Expert)[2010-3-30 12:13]: Q: I created a OS design with KITL and kernel debugger enabled. But I am unable to connect to the target for debugging. I am getting the following error when i try to connect with the device. PB Debugger Cannot initialize the Kernel Debugger. PB Debugger Debugger could not initialize connection. PB Debugger The Kernel Debugger is waiting to connect with target. PB Debugger The Kernel Debugger has been disconnected successfully. A: One possibility is that a rogue cesvchost.exe has co-opted the debugger. I am assuming this is CE 6.0? Can you try exiting visual studio and manually killing the cesvchost.exe process from the Task Manager? davbo-msft (Moderator)[2010-3-30 12:14]: Q: Hi guys, what's the formal way to report bugs back to the core team / product team? The mechanism of calling the support phone number every time is really onerous and time-consuming. Is there another mechanism? A: For info on contacting Microsoft support refer to the support page on the Embedded website: http://msdn.microsoft.com/en-us/windowsembedded/dd897633.aspx Sing Wee [MS] (Expert)[2010-3-30 12:16]: Q: Do u mean ISR/IST implementation? How can i register an interrupt? What kind of interrupt should i register? A: A good introduction to interrupts in WinCE 6.0 can be found here (aside from the documentation on MSDN): http://download.microsoft.com/download/9/c/f/9cffaa58-4000-48d6-a4b2-5fed9e4e6410/Chapter%206%20-%20Developing%20Device%20Drivers.pdf mikehall_ms (Moderator)[2010-3-30 12:16]: Q: What will be different in Windows Compact 7 from CE 6.0? A: Unfortunately we cannot discuss unreleased products on this chat - keep an eye on the Windows Embedded web site and blogs to keep up to date with product announcements. Travis Hobrla [MS] (Expert)[2010-3-30 12:16]: Q: I am using CE 6.0. There is no cesvchost process running in my system. A: What operating system are you using? Karel Danihelka [MS] (Expert)[2010-3-30 12:16]: Q: So...I have to modify file system code to create 2 partition at system startup ?!! I haven't understood.... A: You don't need to modify code, there are registry settings to achive this (look to documentation). But you may need to create partition table in boot loader. Unfortunatelly there isn't simple way how to do it. davbo-msft (Moderator)[2010-3-30 12:18]: Q: I would like to get a handle to a Silverlight screen section, is that possiable? A: Windows Embedded CE 6.0 R3 includes Sliverlight for Windows Embedded. Refer to New Features overview on the embedded web site. http://www.microsoft.com/windowsembedded/en-us/products/windowsce/default.mspx. Silverlight - The power of Silverlight brought to Windows Embedded CE to create rich applications and user interfaces is new part of Windows CE Embedded. mikehall_ms (Moderator)[2010-3-30 12:20]: Q: The link for developing device drivers is not working. can u please check that? A: http://msdn.microsoft.com/en-us/library/ms923714.aspx davbo-msft (Moderator)[2010-3-30 12:20]: Q: I would like to get a handle to a Silverlight screen section, is that possiable? A: Sorry misunderstood the question I thought you were asking if embedded CE could handle Silverlight. Please repost so that the question goes back into the active queue because once answered no way to put the status back to open. Travis Hobrla [MS] (Expert)[2010-3-30 12:21]: Q: sorry! Windows XP SP3 A: Can you try exiting VS2005 and confirming cesvchost.exe is not running, then renaming C:\Documents and Settings\USERNAME\Local Settings\Application Data\Microsoft\CoreCon\1.0 to 1.0_backup, then restarting VS2005? Sing Wee [MS] (Expert)[2010-3-30 12:24]: Q: Can I have the book's name please? A: I believe the downloadable version is related to the last link I sent. If you go to the following website, I believe you can download the whole thing: http://msdn.microsoft.com/en-us/windowsembedded/ce/cc294468.aspx davbo-msft (Moderator)[2010-3-30 12:24]: Q: If one has an image on a Silverlight page, it seems to be cached. How would one refresh that cache after changing the underlying image? A: change the URI of the image or use a writeable bitmap if they want to manually toggle the pixels Sing Wee [MS] (Expert)[2010-3-30 12:25]: A: Whoops, hit [ENTER] too early. On the right side, you'll see there an "Exam Preparation Kit" link that can be downloaded in several different languages. Sing Wee [MS] (Expert)[2010-3-30 12:25]: Q: Can I have the book's name please? A: Whoops, hit [ENTER] too early. On the right side, you'll see there an "Exam Preparation Kit" link that can be downloaded in several different languages. Karel Danihelka [MS] (Expert)[2010-3-30 12:26]: Q: I have a NAND Flash on my target device. On this flash I have the hive registry and an application.I have observed that when the NAND flash is fully, the system startup time is longer....is there a degradation of NAND use that influences the startup time ? Why ? A: Yes - on boot flash abstraction library (old one) read metadata from all sectors to rebuild physical - logical mapping table. davbo-msft (Moderator)[2010-3-30 12:27]: Q: I would like to get a handle to a Silverlight screen section, is that possiable? A: Need addition info on this question. Can you provide more details on what you are trying to do in Silverlight? davbo-msft (Moderator)[2010-3-30 12:27]: Q: If one has an image on a Silverlight page, it seems to be cached. How would one refresh that cache after changing the underlying image? A: Additonal Info: if you want to manually touch the pixels use WriteableBitmap if you want to use the underlying HWND then use IXRVisualHost::GetHWND() davbo-msft (Moderator)[2010-3-30 12:28]: Q: Writable bitmap, is there an example of the syntax? A: if you want to manually touch the pixels use WriteableBitmap if you want to use the underlying HWND then use IXRVisualHost::GetHWND() davbo-msft (Moderator)[2010-3-30 12:29]: Q: I would like to get a handle to a Silverlight screen section, is that possiable? A: Can I get more information about this question about what you are trying to accomplish in Silverlight? davbo-msft (Moderator)[2010-3-30 12:31]: Q: IXRVisualHost::GetHWND() exactly what I needed Thanks, A: Your welcome Sing Wee [MS] (Expert)[2010-3-30 12:31]: Q: ok. thanks for the book's link A: No problem. Travis Hobrla [MS] (Expert)[2010-3-30 12:32]: Q: Typically for SoC devices you name your hardware specific libraries in the form "SOCDIRNAME_LIBNAME". In our platform "OMAP35XX_TPS659XX_TI_V1" if you do this we cause the catalog parser to die... For example if we have a library "Musbfn_OMAP35XX_TPS659XX_TI_V1.dll" entering this in the catalogs pbcxml file in a <module> section causes the XML parser to fail with : Error 3 The 'urn:Microsoft.PlatformBuilder/Catalog:Module' element is invalid - The value '012345678901234567890123456789.dll' is invalid according to its datatype 'urn:Microsoft.PlatformBuilder/Catalog:CatalogFileName' - The actual length is greater than the MaxLength value. A: There are a couple workarounds I can think of. I believe the Module element is only used when doing SYSGEN parsing to make sure dependent SYSGENs are present when the item is selected, so I believe it is optional to the catalog. The other obvious workaround is to shorten the soc name. I realize neither of these solutions is ideal. This is not something we anticipated when we tested CE6.0, sorry. Travis Hobrla [MS] (Expert)[2010-3-30 12:33]: Q: I am getting this error only when I select the KdStub as the debugger in Target device connectivity. A: Right, but KdStub is the debugger that you should use. Have you tried the steps I suggested? Travis Hobrla [MS] (Expert)[2010-3-30 12:36]: Q: If I select Active KTIL, My OS doesn't boots. It says "loading NK.EXE at 0x<xxxxx> location" after that nothing comes in the debug log. A: Can you look at the serial debug output and see what is happening there? Often it can give you a clue to the KITL driver malfunctioning. Travis Hobrla [MS] (Expert)[2010-3-30 12:38]: Q: I have tried that and I am getting the same error. A: I am assuming you have a device created in Target -> Connectivity Options in Platform Builder. What are the Kernel download / Kernel transport for your device? Travis Hobrla [MS] (Expert)[2010-3-30 12:40]: Q: KITL: *** Device Name CEPC56059 *** WARN: KITL will run in polling mode VBridge:: built on [Jul 10 2009] time [10:20:14] VBridgeInit()...TX = [16384] bytes -- Rx = [16384] bytes Tx buffer [0xA1B84860] to [0xA1B88860]. Rx buffer [0xA1B88880] to [0xA1B8C880]. VBridge:: NK add MAC: [0-60-65-2-DA-FB] Connecting to Desktop KITL: Connected host IP: 1 Port: 1086 .. this is the output of the serial debug A: This looks reasonable and does not give clues as to why boot would halt at that point. If you capture a network trace or turn on KITL debug zones via dpCurSettings in kitl.dll, do you see KITL active after this? Travis Hobrla [MS] (Expert)[2010-3-30 12:41]: Q: Both is happening via Ethernet. A: Only thing I have left to suggest is a Platform Builder installation Repair, then. Karel Danihelka [MS] (Expert)[2010-3-30 12:42]: Q: Hi, I saw that the ATADISK is quite generic and des not have any optimizations. Do you have any advice to consider while tryin to improve the performance of it? A: If I remember correctly sample code has support for some specific hardware controllers (little obsolete now). This should be good start point (if you will not decide take existing driver as sample and write you own). Travis Hobrla [MS] (Expert)[2010-3-30 12:44]: Q: I didn't do that. I have to try. A: I think that's the next valid step. You need to figure out whether KITL is hanging or the device - use instrumented serial debug messages and network trace to determine this. Sing Wee [MS] (Expert)[2010-3-30 12:46]: Q: KITL: *** Device Name CEPC56059 *** WARN: KITL will run in polling mode VBridge:: built on [Jul 10 2009] time [10:20:14] VBridgeInit()...TX = [16384] bytes -- Rx = [16384] bytes Tx buffer [0xA1B84860] to [0xA1B88860]. Rx buffer [0xA1B88880] to [0xA1B8C880]. VBridge:: NK add MAC: [0-60-65-2-DA-FB] Connecting to Desktop KITL: Connected host IP: 1 Port: 1086 .. this is the output of the serial debug A: Neo, have you by any chance tried looking into your firewall to see if it might be blocking traffic on any particular ports? Wireshark/netmon might be able to help you here if that's the issue. davbo-msft (Moderator)[2010-3-30 12:48]: Q: I lost spell check, how can i get it back A: Hello - can you give additional details about your question? Is this related to a Windows CE Embedded application? masatos_MSFT (Expert)[2010-3-30 12:51]: Q: When attempting to run the CETK cellcore tests the documentation states the pre-requisites include "stinger.ini", "ltk.ini" but windows CE doesn't provide these or document what they fully need to contain. Implicitly you also need "datatrans.xml" which isn't supplied. If you get around this error and steal these from Windows Mobile instead, when you try and run the CETK tests you get a data abort in radiometricsdll.dll. How should we invoke the cellcore parts of CETK? A: Hi Pev, what version of Windows CE and CETK are you using? I do not have the expertise to answer this question, but can find somebody who can. Travis Hobrla [MS] (Expert)[2010-3-30 12:52]: Q: I don't see a kitlcore.dll in my OS. is my debug image fails to load because of that? A: kitl.dll should be all that's needed, kitlcore.lib is linked into that. Travis Hobrla [MS] (Expert)[2010-3-30 12:55]: Q: I've got a platform (not developed by myself) where I2C bus support has to be provided through the OAL as the kernel needs to talk to devices such as the power management IC and gas gauge so a 'proper' I2C driver hanging off device manager isn't possible. This happens to be a polled driver, so obviously it hits the system hard when either under lots of traffic or an error condition occurs and the driver constantly polls. I originally thought that there was no straightforward way to make such code interrupt driven in the kernel (as it's a cludge) but I realised that that's exactly what ETHDBG drivers do. Is there any reason why I shouldn't have a go at implementing a similar mechanism for our kernel resident I2C driver? If not, are there any obvious pitfalls - I've not seen any other BSP's do this in the past... A: You can make a 'proper' driver that calls down into the OAL to do the actual I2C transactions. Alternatively you can build an interrupt-based version in the OAL where you handle everything in the ISR. There is nothing wrong with that so long as the rest of your drivers and app threads can handle longer times with interrupts off while you are servicing I2C interrupts. Sing Wee [MS] (Expert)[2010-3-30 12:55]: Q: I am having trouble with my mouse, I have the microsoft wireless mobile mouse 3000, when I push the scroll button I am suppose to have autoscroll instead it shows other web pages,Can you help me out tell me what to do!!! A: Sorry, this current chat is about Windows Embedded Compact. Hope you're able to find an answer to your question elsewhere. davbo-msft (Moderator)[2010-3-30 12:56]: Q: Is the Silverlight Animation "Spline" a BezierSpline? A: Spline - http://msdn.microsoft.com/en-us/library/ee501495.aspx<BR< a>> masatos_MSFT (Expert)[2010-3-30 12:57]: Thanks for the info Pev. I will follow up with the CETK experts here and get back to you. davbo-msft (Moderator)[2010-3-30 12:59]: Q: Spline- bad link A: http://msdn.microsoft.com/en-us/library/ee501495.aspx davbo-msft (Moderator)[2010-3-30 13:0]: Q: Sorry, got to tirm the ">" A: No Worries http://msdn.microsoft.com/en-us/library/ee501495.aspx davbo-msft (Moderator)[2010-3-30 13:0]: Hello everyone, we are just about out of time. Thank you for joining us for our Windows Embedded CE 6.0 chat today! <http://www.Microsoft.com/Embedded>; A special thank you to the product group members for coming out. The transcript of today’s chat will be posted online as soon as possible, to <http://msdn.microsoft.com/en-us/chats>;. We’ll see you again for another chat next month. Please check <http://msdn.microsoft.com/en-us/chats>; for the list of upcoming chats. If you still have unanswered questions, let me suggest that you post them on one of our newsgroups on <http://msdn.microsoft.com/en-us/windowsembedded/ce/default.aspx> -Windows Embedded CE 6.0 R3 Now Available! <http://msdn.microsoft.com/windowsembedded/ce/dd630616.aspx>; davbo-msft (Moderator)[2010-3-30 13:1]: Q: hi everybody. I would like to know if there is something know about a bug in RTC API (VOIP), especially when using SIP. According the to the analysis with application verifyier there is a heap link in rtcdllmedia.dll. All of the unreleased chunks seem to have a size of 6560 bytes. A: I will follow up with the Networking Team for a response. davbo-msft (Moderator)[2010-3-30 13:1]: Q: Hi, we've problems with debugging of applications (= breakpoints in Platform Builder will be ignored) over KITL on Windows CE 5.0, if the PDB files are large (over 60MB). Are there any limitations to size of the PDB files? A: I will follow up with the tools team for a response and post with the transcript. Sing Wee [MS] (Expert)[2010-3-30 13:1]: Q: I am unable to use the target control in my development environment. any ideas? A: Make sure you have SYSGEN_SHELL=1 set in your build environment. davbo-msft (Moderator)[2010-3-30 13:3]: Q: what are the main differences between Object Store and RAM disk ? They are both in RAM...are there performance differences ? access differences ? A: I will follow up with the Core Team and get a response posted with the transcript to MSDN The Questions [2010-3-30 12:57]: Thanks for the info Pev. I will follow up with the CETK experts here and get back to you. [2010-3-30 12:59]: [2010-3-30 13:0]: [2010-3-30 13:0]: Hello everyone, we are just about out of time. Thank you for joining us for our Windows Embedded CE 6.0 chat today! <http://www.Microsoft.com/Embedded>; A special thank you to the product group members for coming out. The transcript of today’s chat will be posted online as soon as possible, to <http://msdn.microsoft.com/en-us/chats>;. We’ll see you again for another chat next month. Please check <http://msdn.microsoft.com/en-us/chats>; for the list of upcoming chats. If you still have unanswered questions, let me suggest that you post them on one of our newsgroups on <http://msdn.microsoft.com/en-us/windowsembedded/ce/default.aspx> -Windows Embedded CE 6.0 R3 Now Available! <http://msdn.microsoft.com/windowsembedded/ce/dd630616.aspx>; [2010-3-30 13:1]: [2010-3-30 13:1]: [2010-3-30 13:1]: [2010-3-30 13:3]: neo (Guest)[2010-3-30 11:37]: Hi all KellyG (Guest)[2010-3-30 11:37]: Hi KellyG (Guest)[2010-3-30 11:37]: I have a question unrelated to windows Ce embedded, can you please help me?? neo (Guest)[2010-3-30 11:38]: I need to implement hardware timers on my windows CE 6.0 device to trigger events at microsecond intervals! c neo (Guest)[2010-3-30 11:38]: yes. post it. May be i cud give a try KellyG (Guest)[2010-3-30 11:38]: My Product key listed on my tower is not the product key I need for microsoft office, but that is the only product key listed. neo (Guest)[2010-3-30 11:39]: I hope this is a chat for windows embedded. please post ur queries in office forums KellyG (Guest)[2010-3-30 11:39]: it is but i could not find a forum for office neo (Guest)[2010-3-30 11:40]: I think moderators will help u out. @ davbo-msft: can u help this guy? neo (Guest)[2010-3-30 11:41]: Q: I need to implement hardware timers on my windows CE 6.0 device to trigger events at microsecond intervals. Where should i start? davbo-msft (Moderator)[2010-3-30 11:50]: Our chat today covers the topic of Windows Embedded CE! 1. This chat will last for one hour. During this hour, our Experts will respond to as many questions as they can. Please understand that there may be some questions we cannot respond to due to lack of information or because the information is not yet public. 2. We encourage you to submit questions for our Experts. To do so, type your questions in the send box, select the “ask the Experts” box and click SEND. Questions sent directly to the Guest Chat room will not be answered by the Experts, but we encourage other community members to assist. 3. We ask that you stay on topic for the duration of the chat. This helps the Guests and Experts follow the conversation more easily. We invite you to ask off topic questions after this chat is over, but not during. 4. Please abide by the Chat Code of Conduct. Chat code of conduct: <http://msdn.microsoft.com/chats/chatroom.aspx?ctl=hlp#Conduct>; Pev (Guest)[2010-3-30 11:54]: Evening! davbo-msft (Moderator)[2010-3-30 11:54]: Hello everyone this is Dave Boyce - I worked in the Multimedia area for Windows CE. neo (Guest)[2010-3-30 11:55]: hello dave neo (Guest)[2010-3-30 11:55]: The chat code of conduct link is not working! Pev (Guest)[2010-3-30 11:56]: Best be polite just in case then ;-) neo (Guest)[2010-3-30 11:56]: davbo-msft (Moderator)[2010-3-30 11:57]: I'll check out the issue w/ the link paolopat (Guest)[2010-3-30 12:0]: Hello davbo-msft (Moderator)[2010-3-30 12:0]: We are pleased to welcome our Experts for today’s chat. I will have them introduce themselves now. Chat will begin in a couple of minutes. <http://www.Microsoft.com/Embedded>; paolopat (Guest)[2010-3-30 12:3]: Hello Experts ! neo (Guest)[2010-3-30 12:3]: Welcome all! paolopat (Guest)[2010-3-30 12:3]: Q: I want to partition my NAND Flash device. One partition to use for hive ragistry and the other for the apps and data. The only way to do it is programmatically or setting some registry values ? neo (Guest)[2010-3-30 12:3]: Q: I need to implement hardware timers on my windows CE 6.0 device to trigger events at microsecond intervals. Where should i start? neo (Guest)[2010-3-30 12:5]: Q: My CPU is Intel celeron M processor 1Ghz. Pev (Guest)[2010-3-30 12:5]: neo: if your silicon has multiple general purpose timers, pick one that's not in use for the system timer / profiler and set it up to trigger irqs for your purpose. You can't guarantee hard realtime type responses though... GarySwalling (Guest)[2010-3-30 12:5]: Q: Is Windows Phone 7 related to Windows CE? If so, can you tell me what version of Windows CE is the basis? Is it in fact the new version of Windows Mobile? Pev (Guest)[2010-3-30 12:6]: Q: Hi guys, what's the formal way to report bugs back to the core team / product team? The mechanism of calling the support phone number every time is really onerous and time-consuming. Is there another mechanism? paolopat (Guest)[2010-3-30 12:6]: Q: But the operation for creating the partitions ? neo (Guest)[2010-3-30 12:6]: Q: If i need to implement it using interrupt handlers, What are all the files that I should look at? GPM (Guest)[2010-3-30 12:6]: Q: I would like to get a handle to a Silverlight screen section, is that possiable? Jhony (Guest)[2010-3-30 12:7]: Q: I created a OS design with KITL and kernel debugger enabled. But I am unable to connect to the target for debugging. I am getting the following error when i try to connect with the device. PB Debugger Cannot initialize the Kernel Debugger. PB Debugger Debugger could not initialize connection. PB Debugger The Kernel Debugger is waiting to connect with target. PB Debugger The Kernel Debugger has been disconnected successfully. Charles (Guest)[2010-3-30 12:7]: What will be different in Windows Compact 7 from CE 6.0? neo (Guest)[2010-3-30 12:8]: Can I have the book's name please? kiefs_dev (Guest)[2010-3-30 12:8]: Q: hi everybody. I would like to know if there is something know about a bug in RTC API (VOIP), especially when using SIP. According the to the analysis with application verifyier there is a heap link in rtcdllmedia.dll. All of the unreleased chunks seem to have a size of 6560 bytes. paolopat (Guest)[2010-3-30 12:10]: Q: So...I have to modify file system code to create 2 partition at system startup ?!! I haven't understood.... neo (Guest)[2010-3-30 12:10]: Q: Do u mean ISR/IST implementation? How can i register an interrupt? What kind of interrupt should i register? neo (Guest)[2010-3-30 12:11]: Q: Can I have the book's name please? Charles (Guest)[2010-3-30 12:11]: Q: What will be different in Windows Compact 7 from CE 6.0? PaulT (Guest)[2010-3-30 12:11]: neo: I'd say that you really need the docs for YOUR BSP, not generic documents for BSPs in general. Each BSP may be architected differently. If you're using the CEPC BSP, then the documentation that comes with Platform Builder is a reasonable place to look. GPM (Guest)[2010-3-30 12:11]: Q: If one has an image on a Silverlight page, it seems to be cached. How would one refresh that cache after changing the underlying image? Elektrobit (Guest)[2010-3-30 12:12]: Q: Hi, we've problems with debugging of applications (= breakpoints in Platform Builder will be ignored) over KITL on Windows CE 5.0, if the PDB files are large (over 60MB). Are there any limitations to size of the PDB files? Jhony (Guest)[2010-3-30 12:15]: Q: I am using CE 6.0. There is no cesvchost process running in my system. alexquisi (Guest)[2010-3-30 12:15]: Q: Hi, I saw that the ATADISK is quite generic and des not have any optimizations. Do you have any advice to consider while tryin to improve the performance of it? Jhony (Guest)[2010-3-30 12:17]: Windows XP service pack 1 Jhony (Guest)[2010-3-30 12:17]: Q: sorry! Windows XP SP3 neo (Guest)[2010-3-30 12:19]: Q: The link for developing device drivers is not working. can u please check that? paolopat (Guest)[2010-3-30 12:20]: Q: I have a NAND Flash on my target device. On this flash I have the hive registry and an application.I have observed that when the NAND flash is fully, the system startup time is longer....is there a degradation of NAND use that influences the startup time ? Why ? Pev (Guest)[2010-3-30 12:20]: Q: When attempting to run the CETK cellcore tests the documentation states the pre-requisites include "stinger.ini", "ltk.ini" but windows CE doesn't provide these or document what they fully need to contain. Implicitly you also need "datatrans.xml" which isn't supplied. If you get around this error and steal these from Windows Mobile instead, when you try and run the CETK tests you get a data abort in radiometricsdll.dll. How should we invoke the cellcore parts of CETK? Pev (Guest)[2010-3-30 12:21]: Hi all, Pev (Guest)[2010-3-30 12:21]: oops Pev (Guest)[2010-3-30 12:21]: :-D Pev (Guest)[2010-3-30 12:24]: Typically for SoC devices you name your hardware specific libraries in the form "SOCDIRNAME_LIBNAME". In our platform "OMAP35XX_TPS659XX_TI_V1" if you do this we cause the catalog parser to die... For example if we have a library "Musbfn_OMAP35XX_TPS659XX_TI_V1.dll" entering this in the catalogs pbcxml file in a <module> section causes the XML parser to fail with : Pev (Guest)[2010-3-30 12:25]: Q: Error 3 The 'urn:Microsoft.PlatformBuilder/Catalog:Module' element is invalid - The value '012345678901234567890123456789.dll' is invalid according to its datatype 'urn:Microsoft.PlatformBuilder/Catalog:CatalogFileName' - The actual length is greater than the MaxLength value. GPM (Guest)[2010-3-30 12:25]: Q: Writable bitmap, is there an example of the syntax? Pev (Guest)[2010-3-30 12:25]: Q: Typically for SoC devices you name your hardware specific libraries in the form "SOCDIRNAME_LIBNAME". In our platform "OMAP35XX_TPS659XX_TI_V1" if you do this we cause the catalog parser to die... For example if we have a library "Musbfn_OMAP35XX_TPS659XX_TI_V1.dll" entering this in the catalogs pbcxml file in a <module> section causes the XML parser to fail with : Error 3 The 'urn:Microsoft.PlatformBuilder/Catalog:Module' element is invalid - The value '012345678901234567890123456789.dll' is invalid according to its datatype 'urn:Microsoft.PlatformBuilder/Catalog:CatalogFileName' - The actual length is greater than the MaxLength value. Pev (Guest)[2010-3-30 12:25]: sorry, messed up submission there! GPM (Guest)[2010-3-30 12:26]: Q: I would like to get a handle to a Silverlight screen section, is that possiable? GPM (Guest)[2010-3-30 12:28]: Q: IXRVisualHost::GetHWND() exactly what I needed Thanks, PaulT (Guest)[2010-3-30 12:29]: GPM: You don't have to keep submitting the questions. The chat experts have an application that they're using to follow the chat and all Ask the Experts questions are logged. Jhony (Guest)[2010-3-30 12:29]: Q: I am getting this error only when I select the KdStub as the debugger in Target device connectivity. neo (Guest)[2010-3-30 12:30]: Q: ok. thanks for the book's link Pev (Guest)[2010-3-30 12:31]: Hm, did those two I submitted get picked up by anyone? neo (Guest)[2010-3-30 12:33]: Q: If I select Active KTIL, My OS doesn't boots. It says "loading NK.EXE at 0x<xxxxx> location" after that nothing comes in the debug log. PaulT (Guest)[2010-3-30 12:34]: Pev: PaulT (Guest)[2010-3-30 12:35]: Pev: I'm sure they did. The guys who are actually on the chat may not be experts in that part of things. That's usually the explanation when you don't get an answer in 10 minutes or so. Pev (Guest)[2010-3-30 12:36]: Ah, fair enough Susie (Guest)[2010-3-30 12:36]: My Outlook Express incoming mail is corrput. No ONE has been able to fix the problem, Dell or Norton. I have dial up I'm in a rural area Jhony (Guest)[2010-3-30 12:37]: Q: I have tried that and I am getting the same error. Pev (Guest)[2010-3-30 12:37]: Susie : Use Thunderbird instead :-D PaulT (Guest)[2010-3-30 12:37]: Susie: Sorry, but this chat is not about Windows, but Embedded (like what runs on a phone). Your best chance is to find a local expert or talk to your ISP. paolopat (Guest)[2010-3-30 12:37]: Q: what are the main differences between Object Store and RAM disk ? They are both in RAM...are there performance differences ? access differences ? Susie (Guest)[2010-3-30 12:38]: My computer knowlege is very limited, what is Thunderbird? Pev (Guest)[2010-3-30 12:38]: A different email client :-D neo (Guest)[2010-3-30 12:39]: Q: KITL: *** Device Name CEPC56059 *** WARN: KITL will run in polling mode VBridge:: built on [Jul 10 2009] time [10:20:14] VBridgeInit()...TX = [16384] bytes -- Rx = [16384] bytes Tx buffer [0xA1B84860] to [0xA1B88860]. Rx buffer [0xA1B88880] to [0xA1B8C880]. VBridge:: NK add MAC: [0-60-65-2-DA-FB] Connecting to Desktop KITL: Connected host IP: 1 Port: 1086 .. this is the output of the serial debug Susie (Guest)[2010-3-30 12:39]: Do I need to uninstall Outlook Express youngboyzie (Guest)[2010-3-30 12:39]: I need to start battery calibration for my new battery for my dell inspiron 1525 laptop and should be able to reach the BIOS screen by hitting f2 but this isnt working... help? Pev (Guest)[2010-3-30 12:39]: Nah, you can run it instead - you'll still need help from your ISP to configure it I expect Jhony (Guest)[2010-3-30 12:39]: Q: Both is happening via Ethernet. PaulT (Guest)[2010-3-30 12:40]: youngboyzie: You're off-topic. This is not a general chat for Windows and certainly not for Dell. You'll have to ask Dell how to get to setup; it's their machine. bill (Guest)[2010-3-30 12:41]: I lost spell check, how can i get et back neo (Guest)[2010-3-30 12:42]: Q: I didn't do that. I have to try. Jhony (Guest)[2010-3-30 12:43]: Q: Ok. I will do it then. bill (Guest)[2010-3-30 12:43]: Q: I lost spell check, how can i get it back PaulT (Guest)[2010-3-30 12:44]: bill: This isn't a general Windows chat. There are some Web forums that you might try. GarySwalling (Guest)[2010-3-30 12:45]: Q: Thanks, I found the Phone 7 presentation at http://live.visitmix.com/MIX10/Sessions/CL13 GPM (Guest)[2010-3-30 12:45]: Q: Is the Silverlight Animation "Spline" a BezierSpline? neo (Guest)[2010-3-30 12:46]: Q: ok. I'll do it. thanks Pev (Guest)[2010-3-30 12:46]: Whowever was asking about KITL connection : I've had this loads in the past. I think I started debugging last time by using wireshark to see what was happening on the network then setting up the OAL_ETHER and OAL_FUNC and OAL_VERBOSE as well as OAL_KITL flags to see what was actually happening in the driver.... Pev (Guest)[2010-3-30 12:47]: I'd generally make sure that you're testing though a 10baseT hub (instead of anything faster) and forcing Active KITL in polled mode too... neo (Guest)[2010-3-30 12:48]: Q: I disabled the firewall in my PC. Pev (Guest)[2010-3-30 12:50]: Q: I've got a platform (not developed by myself) where I2C bus support has to be provided through the OAL as the kernel needs to talk to devices such as the power management IC and gas gauge so a 'proper' I2C driver hanging off device manager isn't possible. This happens to be a polled driver, so obviously it hits the system hard when either under lots of traffic or an error condition occurs and the driver constantly polls. I originally thought that there was no straightforward way to make such code interrupt driven in the kernel (as it's a cludge) but I realised that that's exactly what ETHDBG drivers do. Is there any reason why I shouldn't have a go at implementing a similar mechanism for our kernel resident I2C driver? If not, are there any obvious pitfalls - I've not seen any other BSP's do this in the past... neo (Guest)[2010-3-30 12:51]: Q: I don't see a kitlcore.dll in my OS. is my debug image fails to load because of that? Pev (Guest)[2010-3-30 12:52]: Q: Hi masatos, I'm using Windows Embedded CE 6.0 with R3 and patched to feb 2010's QFE's (with it's associated CETK version) this is a machine with only CE 6.0 on (no conflicts with earlier CE or WM...) neo (Guest)[2010-3-30 12:54]: ok. Got it neo (Guest)[2010-3-30 12:54]: Q: ok. Got it Roundman (Guest)[2010-3-30 12:55]: Q: I am having trouble with my mouse, I have the microsoft wireless mobile mouse 3000, when I push the scroll button I am suppose to have autoscroll instead it shows other web pages,Can you help me out tell me what to do!!! Pev (Guest)[2010-3-30 12:55]: Hey neo, debugging kitl issues is really frustrating but dont lose heart :-) neo (Guest)[2010-3-30 12:55]: @ pev : u fixed the problem of KITL after that? neo (Guest)[2010-3-30 12:56]: I am getting the same error again and again. I even cleaned my environment and tried in a fresh PC. But didn't succeed yet Pev (Guest)[2010-3-30 12:56]: Well, eventually - my experiences probably won't help you as different platforms have different reasons for doing that neo (Guest)[2010-3-30 12:56]: I think so PaulT (Guest)[2010-3-30 12:58]: neo: Have you searched the old messages in microsoft.public.windowsce.platbuilder? It seems to me that there was a packet size situation where it was possible to have problems with KITL connections based on a setting on the PC. Google Groups, groups.google.com, Advanced Groups Search will allow you to search a single newsgroup or a set of newsgroups easily. GPM (Guest)[2010-3-30 12:58]: Q: Spline- bad link PaulT (Guest)[2010-3-30 12:58]: GPM: without the > at the end does it work? It seems to for me... neo (Guest)[2010-3-30 12:58]: But some times if i try to connect to the device again. The Image information is seen in the serial debug. what does that mean?Download BIN file information: ----------------------------------------------------- [0]: Base Address=0x220000 Length=0x18DAADC Received a broadcast message !CheckUDP: Not UDP (proto = 0x00000001) after this i am getting the old errors. PB debugger cannot initialize ... GPM (Guest)[2010-3-30 12:59]: Q: Sorry, got to tirm the ">" neo (Guest)[2010-3-30 12:59]: ok paul. I ll look into that. davbo-msft (Moderator)[2010-3-30 13:0]: Hello everyone, we are just about out of time. Thank you for joining us for our Windows Embedded CE 6.0 chat today! <http://www.Microsoft.com/Embedded>; A special thank you to the product group members for coming out. The transcript of today’s chat will be posted online as soon as possible, to <http://msdn.microsoft.com/en-us/chats>;. We’ll see you again for another chat next month. Please check <http://msdn.microsoft.com/en-us/chats>; for the list of upcoming chats. If you still have unanswered questions, let me suggest that you post them on one of our newsgroups on <http://msdn.microsoft.com/en-us/windowsembedded/ce/default.aspx> -Windows Embedded CE 6.0 R3 Now Available! <http://msdn.microsoft.com/windowsembedded/ce/dd630616.aspx>; neo (Guest)[2010-3-30 13:1]: Q: I am unable to use the target control in my development environment. any ideas? Pev (Guest)[2010-3-30 13:1]: Sure, if KITL isn't connected target control won't work as it runs over kitl... neo (Guest)[2010-3-30 13:1]: ok .thanks pev neo (Guest)[2010-3-30 13:2]: yes. sysgen_shell is set to 1 neo (Guest)[2010-3-30 13:2]: Q: yes. sysgen_shell is set to 1 Marcelovk (Guest)[2010-3-30 13:2]: Q: Is there any way to extract the default command lines of the tests in CETK? I want to have it running unconnected from the desktop. Copyright © 2010 – Bruce Eitman All Rights Reserved

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Setting up Mono/ASP.NET 4.0 on Apache2/Ubuntu: Virtual hosts?

- by Dave

I'm attempting to setup Mono/ASP.NET 4.0 on my Apache server (which is running on Ubuntu). Thus far, I've been following a few tutorials/scripts supplied here, and here. As of now: Apache 2.2 is installed (accessible via 'localhost') Mono 2.10.5 is installed However, I'm struggling to configure Apache correctly... apparently the Virtual Host setting isn't doing its job and invoking the mod_mono plugin, nor is it even pulling source from the proper directory. While the Virtual Host setting points to '\srv\www\localhost', it clearly is pulling content instead from 'var/www/', which I've found is the default DocumentRoot for virtual hosts. I can confirm: "/opt/mono-2.10/bin/mod-mono-server4" exists. Virtual hosts file is being read, since undoing the comment in the main httpd.conf changed the root directory from 'htdocs' to 'var/www/' The Mono installation is at least semi-capable of running ASP 4.0, as evidenced by running XSP, navigating to 0.0.0.0:8080/ and getting an ASP.NET style error page with "Mono ASP 4.0.x" at the bottom. Can anyone point out how to fix these configurations and get Mono linked up with Apache? Here are my configs and relevant information: /usr/local/apache2/conf/httpd.conf: # # This is the main Apache HTTP server configuration file. It contains the # configuration directives that give the server its instructions. # See <URL:http://httpd.apache.org/docs/2.2> for detailed information. # In particular, see # <URL:http://httpd.apache.org/docs/2.2/mod/directives.html> # for a discussion of each configuration directive. # # Do NOT simply read the instructions in here without understanding # what they do. They're here only as hints or reminders. If you are unsure # consult the online docs. You have been warned. # # Configuration and logfile names: If the filenames you specify for many # of the server's control files begin with "/" (or "drive:/" for Win32), the # server will use that explicit path. If the filenames do *not* begin # with "/", the value of ServerRoot is prepended -- so "logs/foo_log" # with ServerRoot set to "/usr/local/apache2" will be interpreted by the # server as "/usr/local/apache2/logs/foo_log". # # ServerRoot: The top of the directory tree under which the server's # configuration, error, and log files are kept. # # Do not add a slash at the end of the directory path. If you point # ServerRoot at a non-local disk, be sure to point the LockFile directive # at a local disk. If you wish to share the same ServerRoot for multiple # httpd daemons, you will need to change at least LockFile and PidFile. # ServerRoot "/usr/local/apache2" # # Listen: Allows you to bind Apache to specific IP addresses and/or # ports, instead of the default. See also the <VirtualHost> # directive. # # Change this to Listen on specific IP addresses as shown below to # prevent Apache from glomming onto all bound IP addresses. # #Listen 12.34.56.78:80 Listen 80 # # Dynamic Shared Object (DSO) Support # # To be able to use the functionality of a module which was built as a DSO you # have to place corresponding `LoadModule' lines at this location so the # directives contained in it are actually available _before_ they are used. # Statically compiled modules (those listed by `httpd -l') do not need # to be loaded here. # # Example: # LoadModule foo_module modules/mod_foo.so # <IfModule !mpm_netware_module> <IfModule !mpm_winnt_module> # # If you wish httpd to run as a different user or group, you must run # httpd as root initially and it will switch. # # User/Group: The name (or #number) of the user/group to run httpd as. # It is usually good practice to create a dedicated user and group for # running httpd, as with most system services. # User daemon Group daemon </IfModule> </IfModule> # 'Main' server configuration # # The directives in this section set up the values used by the 'main' # server, which responds to any requests that aren't handled by a # <VirtualHost> definition. These values also provide defaults for # any <VirtualHost> containers you may define later in the file. # # All of these directives may appear inside <VirtualHost> containers, # in which case these default settings will be overridden for the # virtual host being defined. # # # ServerAdmin: Your address, where problems with the server should be # e-mailed. This address appears on some server-generated pages, such # as error documents. e.g. [email protected] # ServerAdmin david@localhost # # ServerName gives the name and port that the server uses to identify itself. # This can often be determined automatically, but we recommend you specify # it explicitly to prevent problems during startup. # # If your host doesn't have a registered DNS name, enter its IP address here. # ServerName localhost:80 # # DocumentRoot: The directory out of which you will serve your # documents. By default, all requests are taken from this directory, but # symbolic links and aliases may be used to point to other locations. # DocumentRoot "/usr/local/apache2/htdocs" # # Each directory to which Apache has access can be configured with respect # to which services and features are allowed and/or disabled in that # directory (and its subdirectories). # # First, we configure the "default" to be a very restrictive set of # features. # <Directory /> Options FollowSymLinks AllowOverride None Order deny,allow Deny from all </Directory> # # Note that from this point forward you must specifically allow # particular features to be enabled - so if something's not working as # you might expect, make sure that you have specifically enabled it # below. # # # This should be changed to whatever you set DocumentRoot to. # <Directory "/usr/local/apache2/htdocs"> # # Possible values for the Options directive are "None", "All", # or any combination of: # Indexes Includes FollowSymLinks SymLinksifOwnerMatch ExecCGI MultiViews # # Note that "MultiViews" must be named *explicitly* --- "Options All" # doesn't give it to you. # # The Options directive is both complicated and important. Please see # http://httpd.apache.org/docs/2.2/mod/core.html#options # for more information. # Options Indexes FollowSymLinks # # AllowOverride controls what directives may be placed in .htaccess files. # It can be "All", "None", or any combination of the keywords: # Options FileInfo AuthConfig Limit # AllowOverride None # # Controls who can get stuff from this server. # Order allow,deny Allow from all </Directory> # # DirectoryIndex: sets the file that Apache will serve if a directory # is requested. # <IfModule dir_module> DirectoryIndex index.html </IfModule> # # The following lines prevent .htaccess and .htpasswd files from being # viewed by Web clients. # <FilesMatch "^\.ht"> Order allow,deny Deny from all Satisfy All </FilesMatch> # # ErrorLog: The location of the error log file. # If you do not specify an ErrorLog directive within a <VirtualHost> # container, error messages relating to that virtual host will be # logged here. If you *do* define an error logfile for a <VirtualHost> # container, that host's errors will be logged there and not here. # ErrorLog "logs/error_log" # # LogLevel: Control the number of messages logged to the error_log. # Possible values include: debug, info, notice, warn, error, crit, # alert, emerg. # LogLevel warn <IfModule log_config_module> # # The following directives define some format nicknames for use with # a CustomLog directive (see below). # LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" combined LogFormat "%h %l %u %t \"%r\" %>s %b" common <IfModule logio_module> # You need to enable mod_logio.c to use %I and %O LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\" %I %O" combinedio </IfModule> # # The location and format of the access logfile (Common Logfile Format). # If you do not define any access logfiles within a <VirtualHost> # container, they will be logged here. Contrariwise, if you *do* # define per-<VirtualHost> access logfiles, transactions will be # logged therein and *not* in this file. # CustomLog "logs/access_log" common # # If you prefer a logfile with access, agent, and referer information # (Combined Logfile Format) you can use the following directive. # #CustomLog "logs/access_log" combined </IfModule> <IfModule alias_module> # # Redirect: Allows you to tell clients about documents that used to # exist in your server's namespace, but do not anymore. The client # will make a new request for the document at its new location. # Example: # Redirect permanent /foo http://www.example.com/bar # # Alias: Maps web paths into filesystem paths and is used to # access content that does not live under the DocumentRoot. # Example: # Alias /webpath /full/filesystem/path # # If you include a trailing / on /webpath then the server will # require it to be present in the URL. You will also likely # need to provide a <Directory> section to allow access to # the filesystem path. # # ScriptAlias: This controls which directories contain server scripts. # ScriptAliases are essentially the same as Aliases, except that # documents in the target directory are treated as applications and # run by the server when requested rather than as documents sent to the # client. The same rules about trailing "/" apply to ScriptAlias # directives as to Alias. # ScriptAlias /cgi-bin/ "/usr/local/apache2/cgi-bin/" </IfModule> <IfModule cgid_module> # # ScriptSock: On threaded servers, designate the path to the UNIX # socket used to communicate with the CGI daemon of mod_cgid. # #Scriptsock logs/cgisock </IfModule> # # "/usr/local/apache2/cgi-bin" should be changed to whatever your ScriptAliased # CGI directory exists, if you have that configured. # <Directory "/usr/local/apache2/cgi-bin"> AllowOverride None Options None Order allow,deny Allow from all </Directory> # # DefaultType: the default MIME type the server will use for a document # if it cannot otherwise determine one, such as from filename extensions. # If your server contains mostly text or HTML documents, "text/plain" is # a good value. If most of your content is binary, such as applications # or images, you may want to use "application/octet-stream" instead to # keep browsers from trying to display binary files as though they are # text. # DefaultType text/plain <IfModule mime_module> # # TypesConfig points to the file containing the list of mappings from # filename extension to MIME-type. # TypesConfig conf/mime.types # # AddType allows you to add to or override the MIME configuration # file specified in TypesConfig for specific file types. # #AddType application/x-gzip .tgz # # AddEncoding allows you to have certain browsers uncompress # information on the fly. Note: Not all browsers support this. # #AddEncoding x-compress .Z #AddEncoding x-gzip .gz .tgz # # If the AddEncoding directives above are commented-out, then you # probably should define those extensions to indicate media types: # AddType application/x-compress .Z AddType application/x-gzip .gz .tgz # # AddHandler allows you to map certain file extensions to "handlers": # actions unrelated to filetype. These can be either built into the server # or added with the Action directive (see below) # # To use CGI scripts outside of ScriptAliased directories: # (You will also need to add "ExecCGI" to the "Options" directive.) # #AddHandler cgi-script .cgi # For type maps (negotiated resources): #AddHandler type-map var # # Filters allow you to process content before it is sent to the client. # # To parse .shtml files for server-side includes (SSI): # (You will also need to add "Includes" to the "Options" directive.) # #AddType text/html .shtml #AddOutputFilter INCLUDES .shtml </IfModule> # # The mod_mime_magic module allows the server to use various hints from the # contents of the file itself to determine its type. The MIMEMagicFile # directive tells the module where the hint definitions are located. # #MIMEMagicFile conf/magic # # Customizable error responses come in three flavors: # 1) plain text 2) local redirects 3) external redirects # # Some examples: #ErrorDocument 500 "The server made a boo boo." #ErrorDocument 404 /missing.html #ErrorDocument 404 "/cgi-bin/missing_handler.pl" #ErrorDocument 402 http://www.example.com/subscription_info.html # # # MaxRanges: Maximum number of Ranges in a request before # returning the entire resource, or 0 for unlimited # Default setting is to accept 200 Ranges #MaxRanges 0 # # EnableMMAP and EnableSendfile: On systems that support it, # memory-mapping or the sendfile syscall is used to deliver # files. This usually improves server performance, but must # be turned off when serving from networked-mounted # filesystems or if support for these functions is otherwise # broken on your system. # #EnableMMAP off #EnableSendfile off # Supplemental configuration # # The configuration files in the conf/extra/ directory can be # included to add extra features or to modify the default configuration of # the server, or you may simply copy their contents here and change as # necessary. # Server-pool management (MPM specific) #Include conf/extra/httpd-mpm.conf # Multi-language error messages #Include conf/extra/httpd-multilang-errordoc.conf # Fancy directory listings #Include conf/extra/httpd-autoindex.conf # Language settings #Include conf/extra/httpd-languages.conf # User home directories #Include conf/extra/httpd-userdir.conf # Real-time info on requests and configuration #Include conf/extra/httpd-info.conf # Virtual hosts Include conf/extra/httpd-vhosts.conf # Local access to the Apache HTTP Server Manual #Include conf/extra/httpd-manual.conf # Distributed authoring and versioning (WebDAV) #Include conf/extra/httpd-dav.conf # Various default settings #Include conf/extra/httpd-default.conf # Secure (SSL/TLS) connections #Include conf/extra/httpd-ssl.conf # # Note: The following must must be present to support # starting without SSL on platforms with no /dev/random equivalent # but a statically compiled-in mod_ssl. # <IfModule ssl_module> SSLRandomSeed startup builtin SSLRandomSeed connect builtin </IfModule> * /usr/local/apache2/conf/extra/httpd-vhosts.conf * # # Virtual Hosts # # If you want to maintain multiple domains/hostnames on your # machine you can setup VirtualHost containers for them. Most configurations # use only name-based virtual hosts so the server doesn't need to worry about # IP addresses. This is indicated by the asterisks in the directives below. # # Please see the documentation at # <URL:http://httpd.apache.org/docs/2.2/vhosts/> # for further details before you try to setup virtual hosts. # # You may use the command line option '-S' to verify your virtual host # configuration. # # Use name-based virtual hosting. # NameVirtualHost *:80 # # VirtualHost example: # Almost any Apache directive may go into a VirtualHost container. # The first VirtualHost section is used for all requests that do not # match a ServerName or ServerAlias in any <VirtualHost> block. # <VirtualHost *:80> ServerName localhost ServerAdmin david@localhost DocumentRoot "/srv/www/localhost" # MonoServerPath can be changed to specify which version of ASP.NET is hosted # mod-mono-server1 = ASP.NET 1.1 / mod-mono-server2 = ASP.NET 2.0 # For SUSE Linux Enterprise Mono Extension, uncomment the line below: # MonoServerPath localhost "/opt/novell/mono/bin/mod-mono-server2" # For Mono on openSUSE, uncomment the line below instead: MonoServerPath localhost "/opt/mono-2.10/bin/mod-mono-server4" # To obtain line numbers in stack traces you need to do two things: # 1) Enable Debug code generation in your page by using the Debug="true" # page directive, or by setting <compilation debug="true" /> in the # application's Web.config # 2) Uncomment the MonoDebug true directive below to enable mod_mono debugging MonoDebug localhost true # The MONO_IOMAP environment variable can be configured to provide platform abstraction # for file access in Linux. Valid values for MONO_IOMAP are: # case # drive # all # Uncomment the line below to alter file access behavior for the configured application MonoSetEnv localhost PATH=/opt/mono-2.10/bin:$PATH;LD_LIBRARY_PATH=/opt/mono-2.10/lib:$LD_LIBRARY_PATH; # # Additional environtment variables can be set for this server instance using # the MonoSetEnv directive. MonoSetEnv takes a string of 'name=value' pairs # separated by semicolons. For instance, to enable platform abstraction *and* # use Mono's old regular expression interpreter (which is slower, but has a # shorter setup time), uncomment the line below instead: # MonoSetEnv localhost MONO_IOMAP=all;MONO_OLD_RX=1 MonoApplications localhost "/:/srv/www/localhost" <Location "/"> Allow from all Order allow,deny MonoSetServerAlias localhost SetHandler mono SetOutputFilter DEFLATE SetEnvIfNoCase Request_URI "\.(?:gif|jpe?g|png)$" no-gzip dont-vary </Location> <IfModule mod_deflate.c> AddOutputFilterByType DEFLATE text/html text/plain text/xml text/javascript </IfModule> </VirtualHost> <VirtualHost *:80> ServerAdmin [email protected] DocumentRoot "/usr/local/apache2/docs/dummy-host.example.com" ServerName dummy-host.example.com ServerAlias www.dummy-host.example.com ErrorLog "logs/dummy-host.example.com-error_log" CustomLog "logs/dummy-host.example.com-access_log" common </VirtualHost> <VirtualHost *:80> ServerAdmin [email protected] DocumentRoot "/usr/local/apache2/docs/dummy-host2.example.com" ServerName dummy-host2.example.com ErrorLog "logs/dummy-host2.example.com-error_log" CustomLog "logs/dummy-host2.example.com-access_log" common </VirtualHost> mono -V output: root@david-ubuntu:~# mono -V Mono JIT compiler version 2.6.7 (Debian 2.6.7-5ubuntu3) Copyright (C) 2002-2010 Novell, Inc and Contributors. www.mono-project.com TLS: __thread GC: Included Boehm (with typed GC and Parallel Mark) SIGSEGV: altstack Notifications: epoll Architecture: amd64 Disabled: none

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