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• problem using the xsl method for-each

  - by joe

  Using XSL I am trying to turn this XML: <book><title>This is a <b>great</b> book</title></book> into this XML: <book>This is a <bold>great</bold> book</book> using this xsl: <xsl:for-each select="book/title/*"> <xsl:choose> <xsl:when test="name() = 'b'"> <bold> <xsl:value-of select="text()"/> </bold> </xsl:when> <xsl:otherwise> <xsl:value-of select="text()"/> </xsl:otherwise> </xsl:choose> </xsl:for-each> but my output is looking like this: <book><bold>great</bold></bold> Can anyone explain why the root text of <title> is getting lost? I believe my for-each select statement may need to be modified but I can't figure out what is should be. Keep in mind that I cannot use an <xsl:template match> because of the complexity of my style sheet. Thanks!

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• How best to implement support for multiple devices in a web application.

  - by Kabeer

  Hello. My client would like a business application to support 'every possible device'. The application in question is essentially a web application and 'every possible device', I believe encompasses mobile phones, netbooks, ipad, other browser supporting devices, etc. The application is somewhat complex w.r.t. the data it captures and other functions it performs (reporting). If I continue to honor increasing complexity in the application, I guess there are more chances of it not working on other devices. I'd like to know how web applications support multiple devices conventionally? Are there multiple versions of presentation layer (like many times I find m.website.com dedicated for mobile devices)? Further, if my application is to take advantage of Java Script, RIA (Flash, SilverLight) then what are the consequences and workarounds? Mine is a .Net based application and the stack also contains Ext JS Java Script library. While I would like to use it for sure, considering that I would be doing a lot of work in Java Script rather than HTML, this could be a problem. The answer to the above could be descriptive. If there is something already prescribed out there, please share the link(s). Thanks.

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• help me refactor iteration over a generic collection

  - by Biswanath

  Hi, I am working with a generic data structure, say MyGeneric<Type>. There is a case where I have to iterate over all the values it holds The code I am trying to do. for ( all the keys in myGeneric ) { // do lot of stuff here } Now the generic can hold base type as double and string and it can hold some user-defined type also. There is a particular situation where I have to some specific work depending upon the type of the generic. so the final code block looks something like this for( all the keys in myGeneric ) { if key is type foo then //do foo foo else if key is of type bar //do bar bar } Now, as complexity sensitive as I am I do not like to have an if condition in the for loop. So the next solution I did was if myGeneric is of type foo call fooIterator(myGeneric) if myGenric is of type bar call barItetrator(myGeneric) function FooIterator() { // ..... // foo work //...... } function BarItetrator() { // ..... // bar work //...... } Then again when somebody sees my code then I am quite sure that they will shout where is the "refactoring". What is the ideal thing to do in this situation ? Thanks.

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• How to refactor models without breaking WPF views?

  - by Tim Murphy

  I've just started learning WPF and like the power of databinding it presents; that is ignoring the complexity and confusion for a noob. My concern is how do you safely refactor your models/viewmodels without breaking the views that use them? Take the following snippet of a view for example: <Grid> <ListView ItemsSource="{Binding Contacts}"> <ListView.View> <GridView> <GridViewColumn Header="First Name" DisplayMemberBinding="{Binding Path=FirstName}"/> <GridViewColumn Header="Last Name" DisplayMemberBinding="{Binding Path=FirstName}"/> <GridViewColumn Header="DOB" DisplayMemberBinding="{Binding Path=DateOfBirth}"/> <GridViewColumn Header="# Pets" DisplayMemberBinding="{Binding Path=NumberOfPets}"/> <GridViewColumn Header="Male" DisplayMemberBinding="{Binding Path=IsMale}"/> </GridView> </ListView.View> </ListView> </Grid> The list is bound to the Contacts property, IList(Of Contact), of the windows DataSource and each of the properties for a Contact is bound to a GridViewColumn. Now if I change the name of the NumberOfPets property in the Contact model to PetCount the view will break. How do I prevent the view breaking?

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• Which options do I have for Java process communication?

  - by Dmitriy Matveev

  We have a place in a code of such form: void processParam(Object param) { wrapperForComplexNativeObject result = jniCallWhichMayCrash(param); processResult(result); } processParam - method which is called with many different arguments. jniCallWhichMayCrash - a native method which is intended to do some complex processing of it's parameter and to create some complex object. It can crash in some cases. wrapperForComplexNativeObject - wrapper type generated by SWIG processResult - a method written in pure Java which processes it's parameter by creation of several kinds (by the kinds I'm not meaning classes, maybe some like hierarchies) of objects: 1 - Some non-unique objects which are referencing each other (from the same hierarchy), these objects can have duplicates created from the invocations of processParam() method with different parameter values. Since it's costly to keep all the duplicates it's necessary to cache them. 2 - Some unique objects which are referencing each other (from the same hierarchy) and some of the objects of 1st kind. After processParam is executed for each of the arguments from some set the data created in processResult will be processed together. The problem is in fact that jniCallWhichMayCrash method may crash the entire JVM and this will be very bad. The reason of crash may be such that it can happen for one argument value and not for the other. We've decided that it's better to ignore crashes inside of JVM and just skip some chunks of data when such crashes occur. In order to do this we should run processParam function inside of separate process and pass the result somehow (HOW? HOW?! This is a question) to the main process and in case of any crashes we will only lose some part of data (It's ok) without lose of everything else. So for now the main problem is implementation of transport between different processes. Which options do I have? I can think about serialization and transmitting of binary data by the streams, but serialization may be not very fast due to object complexity. Maybe I have some other options of implementing this?

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• Are workflows good for web service business logic?

  - by JL

  I have a series of complex web services that are getting used in my SOA application. I am generally happy with the overall design of the application, but as the complexity grows, I was wondering if Windows Workflow might be the way to go. My motivations for this are that you can get a graphic representation of the applications functionality, so it would be easier to maintain the code by its business function, rather than what I have now ( a standard 3 tier class library structure). My concerns are: I would be inducing an abstraction in my code, and I don't want to spend time having to deal with possible WF quirks or bugs. I've never worked with WF, is it a solid technology? I don't want to hit any WF limitations that prevent me from developing my solution. Is a WF even the right solution for the task? Simply put I am considering writing my next web service in this app to call a WF, and in this work flow manage the tasks the web service needs to carry out. I think it will be much neater and easier to maintain than a regular c# class library (maintainable by namespaces, classes ). Do you think this is the right thing to do? I'm hoping for positive feedback on WF (.net 4), but brutal honestly at the end of the day would help more. Thanks

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• Passing System classes as constructor parameters

  - by mcl

  This is probably crazy. I want to take the idea of Dependency Injection to extremes. I have isolated all System.IO-related behavior into a single class so that I can mock that class in my other classes and thereby relieve my larger suite of unit tests of the burden of worrying about the actual file system. But the File IO class I end up with can only be tested with integration tests, which-- of course-- introduces complexity I don't really want to deal with when all I really want to do is make sure my FileIO class calls the correct System.IO stuff. I don't need to integration test System.IO. My FileIO class is doing more than simply wrapping System.IO functions, every now and then it does contain some logic (maybe this is the problem?). So what I'd like is to be able to test my File IO class to ensure that it makes the correct system calls by mocking the System.IO classes themselves. Ideally this would be as easy as having a constructor like so: public FileIO( System.IO.Directory directory, System.IO.File file, System.IO.FileStream fileStream ) { this.Directory = directory; this.File = file; this.FileStream = fileStream; } And then calling in methods like: public GetFilesInFolder(string folderPath) { return this.Directory.GetFiles(folderPath) } But this doesn't fly since the System.IO classes in question are static classes. As far as I can tell they can neither be instantiated in this way or subclassed for the purposes of mocking.

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• Interview Q: sorting an almost sorted array (elements misplaced by no more than k)

  - by polygenelubricants

  I was asked this interview question recently: You're given an array that is almost sorted, in that each of the N elements may be misplaced by no more than k positions from the correct sorted order. Find a space-and-time efficient algorithm to sort the array. I have an O(N log k) solution as follows. Let's denote arr[0..n) to mean the elements of the array from index 0 (inclusive) to N (exclusive). Sort arr[0..2k) Now we know that arr[0..k) are in their final sorted positions... ...but arr[k..2k) may still be misplaced by k! Sort arr[k..3k) Now we know that arr[k..2k) are in their final sorted positions... ...but arr[2k..3k) may still be misplaced by k Sort arr[2k..4k) .... Until you sort arr[ik..N), then you're done! This final step may be cheaper than the other steps when you have less than 2k elements left In each step, you sort at most 2k elements in O(k log k), putting at least k elements in their final sorted positions at the end of each step. There are O(N/k) steps, so the overall complexity is O(N log k). My questions are: Is O(N log k) optimal? Can this be improved upon? Can you do this without (partially) re-sorting the same elements?

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• Web services or shared database for (game) server communication?

  - by jaaronfarr

  We have 2 server clusters: the first is made up of typical web applications backed by SQL databases. The second are highly optimized multiplayer game servers which keep all data in memory. Both clusters communicate with clients via HTTP (Ajax with JSON). There are a few cases in which we need to share data between the two server types, for example, reporting back and storing the results of a game (should ultimately end up in the database). We're considering several approaches for inter-server communication: Just share the MySQL databases between clusters (introduce SQL to the game servers) Sharing data in a distributed key-value store like Memcache, Redis, etc. Use an RPC technology like Google ProtoBufs or Apache Thrift Using RESTful web services (the game server would POST back to the web servers, for example) At the moment, we're leaning towards web services or just sharing the database. Sharing the database seems easy, but we're concerned this adds extra memory and a new dependency into the game servers. Web services provide good separation of concerns and fit with the existing Ajax we use, but add complexity, overhead and many more ways for communication to fail. Are there any other good reasons not to use one or the other approach? Which would be easier to scale?

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• when to use Hibernate vs. Simple ResultSets for small application

  - by luke

  I just started working on upgrading a small component in a distributed java application. The main application is a rather complicated applet/servlet combo running on JBoss and it extensively uses Hibernate for its DataAccess. The component i am working on however is very a very straightforward data importing service. Basically the workflow is Listen for a network event Parse the data packet, extract a set of identifiers Map the identifier set to a primary key in our database Parse the rest of the packet and insert items in a related table using the foreign key found in step 3 Repeat in the previous version of this component it used a hibernate based DAL, that is no longer usable for a variety of reasons (in particular it is EOL), so I am in charge of replacing the Data Access layer for this component. So on the one hand I think i should use Hibernate because that's what the rest of the application does, but on the other i think i should just use regular java.sql.* classes because my requirements are really straightforward and aren't expected to change any time soon. So my question is (and i understand it is subjective) at what point do you think that the added complexity of using an ORM tool (in terms of configuration, dependencies...) is worth it? UPDATE due to the way the DataAccesLayer for the main application was written (weird dependencies) i cannot easily use it, i would have to implement it myself.

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• Django + GAE (Google App Engine) : most convenient path for a beginner?

  - by mac

  Some background info first: Goal: a medium-level complexity web app that I will need to maintain and possibly extend for a few years. Experience: good knowledge of python, some experience of MVC frameworks (in PHP). Desiderata: using django and google app engine. I read extensively about the compatibility issues between GAE and Django, and I am aware of the GAE patch, the norel project, and other similar pieces of code. I have also understood that the SDK provides some of the features of django "out of the box". Yet, given that I have no previous experience with neither Django nor GAE, I am unable to evaluate to which extent using a patched version of Django will strip away important features, or how far the framework provided in the SDK is compatible with Django. So I am rather confused on what would be the best way to proceed in my situation: Should I simply use a patched version of Django as the differences with the original Django are so minor that I would hardly notice them? Should I write my app completely in "regular django" and try to port it to GAE only afterwards, when I will have got a grasp on Django internals and philosophy? Should I write my app using the framework provided with the SDK and port it to django only afterwards? Should I... ? Thank you in advance for your time and advice.

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• Setting the correct orientation for scrollbars in right-to-left pages.

  - by Daniel Lew

  I'm working with right-to-left layouts at the moment (think Hebrew or Arabic). In RTL, the page is generally flipped horizontally. However, I can't figure out how to change the orientation of the scrollbars. I would assume that the scrollbars should appear on the left side of a scrollable element, not the right side like it does in an LTR layout. Here is an example page where the scrollbar still appears on the right: <html dir="rtl"> <body> <div style="height: 100px; overflow: auto;"> <p>This is some text</p> <p>This is some text</p> <p>This is some text</p> <p>This is some text</p> <p>This is some text</p> </body> </html> Is the orientation of a scrollbar a browser locale setting, and thus is not something I should be concerned about, or is there a way to set the orientation of the scrollbar? (I'm not interested in implementing my own JavaScript scrollbar; if it turns out this is just a limitation of browsers then I'd rather live with that than add complexity to the page.)

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• Question about array subscripting in C#

  - by Michael J

  Back in the old days of C, one could use array subscripting to address storage in very useful ways. For example, one could declare an array as such. This array represents an EEPROM image with 8 bit words. BYTE eepromImage[1024] = { ... }; And later refer to that array as if it were really multi-dimensional storage BYTE mpuImage[2][512] = eepromImage; I'm sure I have the syntax wrong, but I hope you get the idea. Anyway, this projected a two dimension image of what is really single dimensional storage. The two dimensional projection represents the EEPROM image when loaded into the memory of an MPU with 16 bit words. In C one could reference the storage multi-dimensionaly and change values and the changed values would show up in the real (single dimension) storage almost as if by magic. Is it possible to do this same thing using C#? Our current solution uses multiple arrays and event handlers to keep things synchronized. This kind of works but it is additional complexity that we would like to avoid if there is a better way.

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• Heap Algorithmic Issue

  - by OberynMarDELL

  I am having this algorithmic problem that I want to discuss about. Its not about find a solution but about optimization in terms of runtime. So here it is: Suppose we have a race court of Length L and a total of N cars that participate on the race. The race rules are simple. Once a car overtakes an other car the second car is eliminated from the race. The race ends when no more overtakes are possible to happen. The tricky part is that the k'th car has a starting point x[k] and a velocity v[k]. The points are given in an ascending order, but the velocities may differ. What I've done so far: Given that a car can get overtaken only by its previous, I calculated the time that it takes for each car to reach its next one t = (x[i] - x[i+1])/(v[i] - v[i+1]) and I insert these times onto a min heap in O(n log n). So in theory I have to pop the first element in O(logn), find its previous, pop it as well , update its time and insert it in the heap once more, much like a priority queue. My main problem is how I can access specific points of a heap in O(log n) or faster in order to keep the complexity in O(n log n) levels. This program should be written on Haskell so I would like to keep things simple as far as possible EDIT: I Forgot to write the actual point of the race. The goal is to find the order in which cars exit the game

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• What is good about php/what is php good for?

  - by Roman A. Taycher

  I have often seen php bashed around the webs as a loosely typed(loose typing as in a lot of type coercion and/or easy(and perhaps common) to cast object all over not dynamic typing) language without a great compiler/interpreter/vm, with even the standard library using a number of different naming conventions. A lot of people complain about perl but many (including a lot of the complainers) also give it a lot of credit for its regexes and general flexibility and power. Other then legacy code , giant web frameworks that can do tons(drupal,ect.), and easy cheap hosting what is good about php (,also what criticism are unfair, and how is the language evolving to overcome its problems). Why would i want to learn it? why would I want to do an independent project in it? The main thing I have heard is that its php codes simplicity is sometimes easier then the over-engineered complexity you find in certain Java frameworks and applications. I'm not just trolling, i'm genuinly curious what makes php programmers use it. try to convince me to put it on my languages to dabble in and languages to learn more in depth lists.

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• What is the best way to create a running integer id on the AppEngine data storage?

  - by Freed

  For various reasons, I need a unique running integer id for my entities stored on the Google AppEngine. The automatically generated key sort of has this behaviour, but it doesn't start from 1 (or 0) and doesn't guarantee that the generated integer part will come from a continuous sequence. What would be the best way to efficiently implement this on AppEngine? Is there any support from the storage system? To add to the complexity, I might need to do this over entities from different entity groups, meaning I can't just get the highest id right now and save an entity with the next id in a transaction. Might memcache be the way to go..? Edit: I havn't yet implemented this, but to clarify on the memcache idea. I know memcache is unreliable, but in practice it probably won't lose data "too often" to hurt performance. Basically, I would have a memcache entry for the last used id, update it (somehow atomically) whenever I create a new entity and use that id. In the case of memcache not having a value for this entry, I'd get the highest id so far by doing a query on my entities sorted by the id and update memcache (unless someone else had already done so). The only problem I can see with this right now would be atomicity of the operation as a whole if the save of my new entity was also part of a transaction. Thoughts..?

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• Data transformation question

  - by tkm

  I have data composed of a list of employers and a list of workers. Each has a many-to-many relationship with the other (so an employer can have many workers, and a worker can have many employers). The way the data is retrieved (and given to me) is as follows: each employer has an array of workers. In other words: employer n has: worker x, worker y etc. So I have a bunch of employer objects each containing an array of workers. I need to transform this data (and basically invert the relationship). I need to have a bunch of worker objects, each containing and array of employers. In other words: worker x has: employer n1, employer n2 etc. The context is hypothetical so please don't comment on why I need this or why I am doing it this way. I would really just like help on the algorithm to perform this transformation (there isn't that much data so I would prefer readability over complex optimizations which reduce complexity). (Oh and I am using Java, but pseudocode would be fine). Thanks!

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• find the difference between two very large list

  - by user157195

  I have two large list(could be a hundred million items), the source of each list can be either from a database table or a flat file. both lists are of comparable sizes, both unsorted. I need to find the difference between them. so I have 3 scenarios: 1. List1 is a database table(assume each row simply have one item(key) that is a string), List2 is a large file. 2. Both lists are from 2 db tables. 3. both lists are from two files. in case 2, I plan to use: select a.item from MyTable a where a.item not in (select b.item form MyTable b) this clearly is inefficient, is there a better way? Another approach is: I plan to sort each list, and then walk down both of them to find the diff. If the list is from a file, I have to read it into a db table first, then use db sorting to output the list. Is the run time complexity still O(nlogn) in db sorting? either approach is a pain and seems would be very slow when the list involved has hundreds of millions of items. any suggestions?

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• KeePass justification

  - by Jeff Walker

  I work at a place that tries to take security seriously, but sadly, they often fail. Currently, one of the major ways they fail is password management. I personally have about 20 accounts (my personal user id on lots of machines). For shared "system" accounts, there are about 45 per environment; development, test, and production. I have access to 2 of those, so my personal total is somewhere around 115 accounts. Passwords have to be at least 15 characters with some extensive but standard complexity constraints, and have to be changed every 60 days or so (system accounts every year). They also should not be the same for different accounts, but that isn't enforced. Think DoD-type standards. There is no way to remember and keep up with this. It just isn't humanly possible, as far as I'm concerned. This might be a good justification of a centralized account management system, a la LDAP or ActiveDirectory, but that is a totally different battle. Currently the solution is an Excel spreadsheet. They use Excel to put a password on it, and then most people make a copy and remove the password. This makes my stomach turn. I use KeePass for this problem and it manages all of my account very well. I like the features like auto-typing, grouping, plugins, password generation, etc. It uses AES-256 encryption via the .Net framework, and while not FIPS compliant, it has a very good reputation. The only problem is that they are also very careful about using randomly downloaded software. So we have to justify every piece of software on our workstations. I have been told that they really don't want me to use this, be cause of the "sensitive nature" of storing passwords. sigh My justification has to be "VERY VERY strong". I have been tasked with writing a justification for KeePass, but as I am lazy, I would like any input that I can get from the community. What do you recommend? Is there something out there that is better or more respected than KeePass? Is there any security experts saying interesting things on this topic? Anything will help at this point. Thanks.

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• How to configure DD-WRT routing table when creating an isolated network segment for PCI C VT compliance

  - by tetranz

  I'm the volunteer support and system admin person at a small private school. We need to setup a PCI compliant Windows PC as a virtual terminal for credit card processing. I've read questionnaire SAQ C-VT and, to quote, this computer needs to be accessed: "via a computer that is isolated in a single location, and is not connected to other locations or systems within your environment (this can be achieved via a firewall or network segmentation to isolate the computer from other systems)" Our setup is as follows: DSL modem from ISP is setup to be a "transparent pipe" with no extra services. That goes into the WAN port of Linksys WRT54-GL running a DD-WRT. The LAN is 192.168.1.x. There are a couple of other WRT54-GL / DD-WRT devices. One is used as a wireless AP and another is a client bridge. To isolate the VT (virtual terminal) machine, I have another DD-WRT device. Its WAN is connected to a port on the 192.168.1.x LAN. The virtual terminal machine is connected to its LAN which is at 192.168.10.x. The SPI Firewall etc is turned on. It's basically the default DD-WRT gateway setup where the "ISP" is our own LAN. That's working. All incoming traffic to the VT machine is blocked, including from our own LAN. The VT can access the internet BUT, and here's the problem, it can also ping any of the computers on the 192.168.1.x LAN. I think I need to stop that. I'm guessing that I could do something with the Static Routing table in the VT machine's DD-WRT device. I need to route anything going to 192.168.1.x other than the gateway which is 192.168.1.1 to 0.0.0.0 or something like that. That's where I'm stuck at the end of my knowledge. Or ... do I need to get yet another DD-WRT so the network is "balanced". Maybe I need to have the internet from the DSL going into a DD-WRT which has only two devices on its LAN i.e., two other DD-WRTs, one for the main LAN and one for the VT. I think that would do but I'd like to avoid the extra cost and complexity if I don't need it. Thanks

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• WCF REST on .Net 4.0

  - by AngelEyes

  A simple and straight forward article taken from: http://christopherdeweese.com/blog2/post/drop-the-soap-wcf-rest-and-pretty-uris-in-net-4 Drop the Soap: WCF, REST, and Pretty URIs in .NET 4 Years ago I was working in libraries when the Web 2.0 revolution began.  One of the things that caught my attention about early start-ups using the AJAX/REST/Web 2.0 model was how nice the URIs were for their applications.  Those were my first impressions of REST; pretty URIs.  Turns out there is a little more to it than that. REST is an architectural style that focuses on resources and structured ways to access those resources via the web.  REST evolved as an “anti-SOAP” movement, driven by developers who did not want to deal with all the complexity SOAP introduces (which is al lot when you don’t have frameworks hiding it all).  One of the biggest benefits to REST is that browsers can talk to rest services directly because REST works using URIs, QueryStrings, Cookies, SSL, and all those HTTP verbs that we don’t have to think about anymore. If you are familiar with ASP.NET MVC then you have been exposed to rest at some level.  MVC is relies heavily on routing to generate consistent and clean URIs.  REST for WCF gives you the same type of feel for your services.  Let’s dive in. WCF REST in .NET 3.5 SP1 and .NET 4 This post will cover WCF REST in .NET 4 which drew heavily from the REST Starter Kit and community feedback.  There is basic REST support in .NET 3.5 SP1 and you can also grab the REST Starter Kit to enable some of the features you’ll find in .NET 4. This post will cover REST in .NET 4 and Visual Studio 2010. Getting Started To get started we’ll create a basic WCF Rest Service Application using the new on-line templates option in VS 2010: When you first install a template you are prompted with this dialog: Dude Where’s my .Svc File? The WCF REST template shows us the new way we can simply build services.  Before we talk about what’s there, let’s look at what is not there: The .Svc File An Interface Contract Dozens of lines of configuration that you have to change to make your service work REST in .NET 4 is greatly simplified and leverages the Web Routing capabilities used in ASP.NET MVC and other parts of the web frameworks.  With REST in .NET 4 you use a global.asax to set the route to your service using the new ServiceRoute class.  From there, the WCF runtime handles dispatching service calls to the methods based on the Uri Templates. global.asax using System; using System.ServiceModel.Activation; using System.Web; using System.Web.Routing; namespace Blog.WcfRest.TimeService {     public class Global : HttpApplication     {         void Application_Start(object sender, EventArgs e)         {             RegisterRoutes();         }         private static void RegisterRoutes()         {             RouteTable.Routes.Add(new ServiceRoute("TimeService",                 new WebServiceHostFactory(), typeof(TimeService)));         }     } } The web.config contains some new structures to support a configuration free deployment.  Note that this is the default config generated with the template.  I did not make any changes to web.config. web.config <?xml version="1.0"?> <configuration>   <system.web>     <compilation debug="true" targetFramework="4.0" />   </system.web>   <system.webServer>     <modules runAllManagedModulesForAllRequests="true">       <add name="UrlRoutingModule" type="System.Web.Routing.UrlRoutingModule,            System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />     </modules>   </system.webServer>   <system.serviceModel>     <serviceHostingEnvironment aspNetCompatibilityEnabled="true"/>     <standardEndpoints>       <webHttpEndpoint>         <!--             Configure the WCF REST service base address via the global.asax.cs file and the default endpoint             via the attributes on the <standardEndpoint> element below         -->         <standardEndpoint name="" helpEnabled="true" automaticFormatSelectionEnabled="true"/>       </webHttpEndpoint>     </standardEndpoints>   </system.serviceModel> </configuration> Building the Time Service We’ll create a simple “TimeService” that will return the current time.  Let’s start with the following code: using System; using System.ServiceModel; using System.ServiceModel.Activation; using System.ServiceModel.Web; namespace Blog.WcfRest.TimeService {     [ServiceContract]     [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]     [ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall)]     public class TimeService     {         [WebGet(UriTemplate = "CurrentTime")]         public string CurrentTime()         {             return DateTime.Now.ToString();         }     } } The endpoint for this service will be http://[machinename]:[port]/TimeService.  To get the current time http://[machinename]:[port]/TimeService/CurrentTime will do the trick. The Results Are In Remember That Route In global.asax? Turns out it is pretty important.  When you set the route name, that defines the resource name starting after the host portion of the Uri. Help Pages in WCF 4 Another feature that came from the starter kit are the help pages.  To access the help pages simply append Help to the end of the service’s base Uri. Dropping the Soap Having dabbled with REST in the past and after using Soap for the last few years, the WCF 4 REST support is certainly refreshing.  I’m currently working on some REST implementations in .NET 3.5 and VS 2008 and am looking forward to working on REST in .NET 4 and VS 2010.

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• New MySQL Cluster 7.3 Previews: Foreign Keys, NoSQL Node.js API and Auto-Tuned Clusters

  - by Mat Keep

  At this weeks MySQL Connect conference, Oracle previewed an exciting new wave of developments for MySQL Cluster, further extending its simplicity and flexibility by expanding the range of use-cases, adding new NoSQL options, and automating configuration. What’s new: Development Release 1: MySQL Cluster 7.3 with Foreign Keys Early Access “Labs” Preview: MySQL Cluster NoSQL API for Node.js Early Access “Labs” Preview: MySQL Cluster GUI-Based Auto-Installer In this blog, I'll introduce you to the features being previewed. Review the blogs listed below for more detail on each of the specific features discussed. Save the date!: A live webinar is scheduled for Thursday 25th October at 0900 Pacific Time / 1600UTC where we will discuss each of these enhancements in more detail. Registration will be open soon and published to the MySQL webinars page MySQL Cluster 7.3: Development Release 1 The first MySQL Cluster 7.3 Development Milestone Release (DMR) previews Foreign Keys, bringing powerful new functionality to MySQL Cluster while eliminating development complexity. Foreign Key support has been one of the most requested enhancements to MySQL Cluster – enabling users to simplify their data models and application logic – while extending the range of use-cases for both custom projects requiring referential integrity and packaged applications, such as eCommerce, CRM, CMS, etc. Implementation The Foreign Key functionality is implemented directly within the MySQL Cluster data nodes, allowing any client API accessing the cluster to benefit from them – whether they are SQL or one of the NoSQL interfaces (Memcached, C++, Java, JPA, HTTP/REST or the new Node.js API - discussed later.) The core referential actions defined in the SQL:2003 standard are implemented: CASCADE RESTRICT NO ACTION SET NULL In addition, the MySQL Cluster implementation supports the online adding and dropping of Foreign Keys, ensuring the Cluster continues to serve both read and write requests during the operation.  This represents a further enhancement to MySQL Cluster's support for on0line schema changes, ie adding and dropping indexes, adding columns, etc.  Read this blog for a demonstration of using Foreign Keys with MySQL Cluster.  Getting Started with MySQL Cluster 7.3 DMR1: Users can download either the source or binary and evaluate the MySQL Cluster 7.3 DMR with Foreign Keys now! (Select the Development Release tab). MySQL Cluster NoSQL API for Node.js Node.js is hot! In a little over 3 years, it has become one of the most popular environments for developing next generation web, cloud, mobile and social applications. Bringing JavaScript from the browser to the server, the design goal of Node.js is to build new real-time applications supporting millions of client connections, serviced by a single CPU core. Making it simple to further extend the flexibility and power of Node.js to the database layer, we are previewing the Node.js Javascript API for MySQL Cluster as an Early Access release, available for download now from http://labs.mysql.com/. Select the following build: MySQL-Cluster-NoSQL-Connector-for-Node-js Alternatively, you can clone the project at the MySQL GitHub page.  Implemented as a module for the V8 engine, the new API provides Node.js with a native, asynchronous JavaScript interface that can be used to both query and receive results sets directly from MySQL Cluster, without transformations to SQL. Figure 1: MySQL Cluster NoSQL API for Node.js enables end-to-end JavaScript development Rather than just presenting a simple interface to the database, the Node.js module integrates the MySQL Cluster native API library directly within the web application itself, enabling developers to seamlessly couple their high performance, distributed applications with a high performance, distributed, persistence layer delivering 99.999% availability. The new Node.js API joins a rich array of NoSQL interfaces available for MySQL Cluster. Whichever API is chosen for an application, SQL and NoSQL can be used concurrently across the same data set, providing the ultimate in developer flexibility.  Get started with MySQL Cluster NoSQL API for Node.js tutorial MySQL Cluster GUI-Based Auto-Installer Compatible with both MySQL Cluster 7.2 and 7.3, the Auto-Installer makes it simple for DevOps teams to quickly configure and provision highly optimized MySQL Cluster deployments – whether on-premise or in the cloud. Implemented with a standard HTML GUI and Python-based web server back-end, the Auto-Installer intelligently configures MySQL Cluster based on application requirements and auto-discovered hardware resources Figure 2: Automated Tuning and Configuration of MySQL Cluster Developed by the same engineering team responsible for the MySQL Cluster database, the installer provides standardized configurations that make it simple, quick and easy to build stable and high performance clustered environments. The auto-installer is previewed as an Early Access release, available for download now from http://labs.mysql.com/, by selecting the MySQL-Cluster-Auto-Installer build. You can read more about getting started with the MySQL Cluster auto-installer here. Watch the YouTube video for a demonstration of using the MySQL Cluster auto-installer Getting Started with MySQL Cluster If you are new to MySQL Cluster, the Getting Started guide will walk you through installing an evaluation cluster on a singe host (these guides reflect MySQL Cluster 7.2, but apply equally well to 7.3 and the Early Access previews). Or use the new MySQL Cluster Auto-Installer! Download the Guide to Scaling Web Databases with MySQL Cluster (to learn more about its architecture, design and ideal use-cases). Post any questions to the MySQL Cluster forum where our Engineering team and the MySQL Cluster community will attempt to assist you. Post any bugs you find to the MySQL bug tracking system (select MySQL Cluster from the Category drop-down menu) And if you have any feedback, please post them to the Comments section here or in the blogs referenced in this article. Summary MySQL Cluster 7.2 is the GA, production-ready release of MySQL Cluster. The first Development Release of MySQL Cluster 7.3 and the Early Access previews give you the opportunity to preview and evaluate future developments in the MySQL Cluster database, and we are very excited to be able to share that with you. Let us know how you get along with MySQL Cluster 7.3, and other features that you want to see in future releases, by using the comments of this blog.

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• Installing Visual Studio Team Foundation Server Service Pack 1

  - by Martin Hinshelwood

  As has become customary when the product team releases a new patch, SP or version I like to document the install. Although I had no errors on my main computer, my netbook did have problems. Although I am not ready to call it a Service Pack problem just yet! Update 2011-03-10 – Running the Team Foundation Server 2010 Service Pack 1 install a second time worked As per Brian's post I am installing the Team Foundation Server Service Pack first and indeed as this is a single server local deployment I need to install both. If I only install one it will leave the other product broken. This however does not affect you if you are running Visual Studio and Team Foundation Server on separate computers as is normal in a production deployment. Main workhorse I will be installing the service pack first on my main computer as I want to actually use it here. Figure: My main workhorse I will also be installing this on my netbook which is obviously of significantly lower spec, but I will do that one after. Although, as always I had my fingers crossed, I was not really worried. Figure: KB2182621 Compared to Visual Studio there are not really a lot of components to update. Figure: TFS 2010 and SQL 2008 are the main things to update There is no “web” installer for the Team Foundation Server 2010 Service Pack, but that is ok as most people will be installing it on a production server and will want to have everything local. I would have liked a Web installer, but the added complexity for the product team is not work the capability for a 500mb patch. Figure: There is currently no way to roll SP1 and RTM together Figure: No problems with the file verification, phew Figure: Although the install took a while, it progressed smoothly   Figure: I always like a success screen Well, as far as the install is concerned everything is OK, but what about TFS? Can I still connect and can I still administer it. Figure: Service Pack 1 is reflected correctly in the Administration Console I am confident that there are no major problems with TFS on my system and that it has been updated to SP1. I can do all of the things that I used before with ease, and with the new features detailed by Brian I think I will be happy. Netbook The great god Murphy has stuck, and my poor wee laptop spat the Team Foundation Server 2010 Service Pack 1 out so fast it hit me on the back of the head. That will teach me for not looking… Figure: “Installation did not succeed” I am pretty sure should not be all caps! On examining the file I found that everything worked, except the actual Team Foundation Server 2010 serving step. Action: System Requirement Checks... Action complete Action: Downloading and/or Verifying Items c:\757fe6efe9f065130d4838081911\VS10-KB2182621.msp: Verifying signature for VS10-KB2182621.msp c:\757fe6efe9f065130d4838081911\VS10-KB2182621.msp Signature verified successfully for VS10-KB2182621.msp c:\757fe6efe9f065130d4838081911\DACFramework_enu.msi: Verifying signature for DACFramework_enu.msi c:\757fe6efe9f065130d4838081911\DACFramework_enu.msi Signature verified successfully for DACFramework_enu.msi c:\757fe6efe9f065130d4838081911\DACProjectSystemSetup_enu.msi: Verifying signature for DACProjectSystemSetup_enu.msi Exists: evaluating Exists evaluated to false c:\757fe6efe9f065130d4838081911\DACProjectSystemSetup_enu.msi Signature verified successfully for DACProjectSystemSetup_enu.msi c:\757fe6efe9f065130d4838081911\TSqlLanguageService_enu.msi: Verifying signature for TSqlLanguageService_enu.msi c:\757fe6efe9f065130d4838081911\TSqlLanguageService_enu.msi Signature verified successfully for TSqlLanguageService_enu.msi c:\757fe6efe9f065130d4838081911\SharedManagementObjects_x86_enu.msi: Verifying signature for SharedManagementObjects_x86_enu.msi c:\757fe6efe9f065130d4838081911\SharedManagementObjects_x86_enu.msi Signature verified successfully for SharedManagementObjects_x86_enu.msi c:\757fe6efe9f065130d4838081911\SharedManagementObjects_amd64_enu.msi: Verifying signature for SharedManagementObjects_amd64_enu.msi c:\757fe6efe9f065130d4838081911\SharedManagementObjects_amd64_enu.msi Signature verified successfully for SharedManagementObjects_amd64_enu.msi c:\757fe6efe9f065130d4838081911\SQLSysClrTypes_x86_enu.msi: Verifying signature for SQLSysClrTypes_x86_enu.msi c:\757fe6efe9f065130d4838081911\SQLSysClrTypes_x86_enu.msi Signature verified successfully for SQLSysClrTypes_x86_enu.msi c:\757fe6efe9f065130d4838081911\SQLSysClrTypes_amd64_enu.msi: Verifying signature for SQLSysClrTypes_amd64_enu.msi c:\757fe6efe9f065130d4838081911\SQLSysClrTypes_amd64_enu.msi Signature verified successfully for SQLSysClrTypes_amd64_enu.msi c:\757fe6efe9f065130d4838081911\vcruntime\Vc_runtime_x86.cab: Verifying signature for vcruntime\Vc_runtime_x86.cab c:\757fe6efe9f065130d4838081911\vcruntime\Vc_runtime_x86.cab Signature verified successfully for vcruntime\Vc_runtime_x86.cab c:\757fe6efe9f065130d4838081911\vcruntime\Vc_runtime_x86.msi: Verifying signature for vcruntime\Vc_runtime_x86.msi c:\757fe6efe9f065130d4838081911\vcruntime\Vc_runtime_x86.msi Signature verified successfully for vcruntime\Vc_runtime_x86.msi c:\757fe6efe9f065130d4838081911\SetupUtility.exe: Verifying signature for SetupUtility.exe c:\757fe6efe9f065130d4838081911\SetupUtility.exe Signature verified successfully for SetupUtility.exe c:\757fe6efe9f065130d4838081911\vcruntime\Vc_runtime_x64.cab: Verifying signature for vcruntime\Vc_runtime_x64.cab c:\757fe6efe9f065130d4838081911\vcruntime\Vc_runtime_x64.cab Signature verified successfully for vcruntime\Vc_runtime_x64.cab c:\757fe6efe9f065130d4838081911\vcruntime\Vc_runtime_x64.msi: Verifying signature for vcruntime\Vc_runtime_x64.msi c:\757fe6efe9f065130d4838081911\vcruntime\Vc_runtime_x64.msi Signature verified successfully for vcruntime\Vc_runtime_x64.msi c:\757fe6efe9f065130d4838081911\NDP40-KB2468871.exe: Verifying signature for NDP40-KB2468871.exe c:\757fe6efe9f065130d4838081911\NDP40-KB2468871.exe Signature verified successfully for NDP40-KB2468871.exe Action complete Action: Performing actions on all Items Entering Function: BaseMspInstallerT >::PerformAction Action: Performing Install on MSP: c:\757fe6efe9f065130d4838081911\VS10-KB2182621.msp targetting Product: Microsoft Team Foundation Server 2010 - ENU Returning IDOK. INSTALLMESSAGE_ERROR [Error 1935.An error occurred during the installation of assembly 'Microsoft.TeamFoundation.WebAccess.WorkItemTracking,version="10.0.0.0",publicKeyToken="b03f5f7f11d50a3a",processorArchitecture="MSIL",fileVersion="10.0.40219.1",culture="neutral"'. Please refer to Help and Support for more information. HRESULT: 0x80070005. ] Returning IDOK. INSTALLMESSAGE_ERROR [Error 1712.One or more of the files required to restore your computer to its previous state could not be found. Restoration will not be possible.] Patch (c:\757fe6efe9f065130d4838081911\VS10-KB2182621.msp) Install failed on product (Microsoft Team Foundation Server 2010 - ENU). Msi Log: MSI returned 0x643 Entering Function: MspInstallerT >::Rollback Action Rollback changes PerformMsiOperation returned 0x643 PerformMsiOperation returned 0x643 OnFailureBehavior for this item is to Rollback. Action complete Final Result: Installation failed with error code: (0x80070643), "Fatal error during installation. " (Elapsed time: 0 00:14:09). Figure: Error log for Team Foundation Server 2010 install shows a failure As there is really no information in this log as to why the installation failed so I checked the event log on that box. Figure: There are hundreds of errors and it actually looks like there are more problems than a failed Service Pack I am going to just run it again and see if it was because the netbook was slow to catch on to the update. Hears hoping, but even if it fails, I would question the installation of Windows (PDC laptop original install) before I question the Service Pack Figure: Second run through was successful I don’t know if the laptop was just slow, or what… Did you get this error? If you did I will push this to the product team as a problem, but unless more people have this sort of error, I will just look to write this off as a corrupted install of Windows and reinstall.

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• CQRS &ndash; Questions and Concerns

  - by Dylan Smith

  I’ve been doing a lot of learning on CQRS and Event Sourcing over the last little while and I have a number of questions that I haven’t been able to answer. 1. What is the benefit of CQRS when compared to a typical DDD architecture that uses Event Sourcing and properly captures intent and behavior via verb-based commands? (other than Scalability) 2. When using CQRS what do you do with complex query-based logic? I’m going to elaborate on #1 in this blog post and I’ll do a follow-up post on #2. I watched through Greg Young’s video on the business benefits of CQRS + Event Sourcing and first let me say that I thought it was an excellent presentation that really drives home a lot of the benefits to this approach to architecture (I watched it twice in a row I enjoyed it so much!). But it didn’t answer some of my questions fully (I wish I had been there to ask these of Greg in person!). So let me pick apart some of the points he makes and how they relate to my first question above. I’m completely sold on the idea of event sourcing and have a clear understanding of the benefits that it brings to the table, so I’m not going to question that. But you can use event sourcing without going to a CQRS architecture, so my main question is around the benefits of CQRS + Event Sourcing vs Event Sourcing + Typical DDD architecture Architecture with Event Sourcing + Commands on Left, CQRS on Right Greg talks about how the stereotypical architecture doesn’t support DDD, but is that only because his diagram shows DTO’s coming up from the client. If we use the same diagram but allow the client to send commands doesn’t that remove a lot of the arguments that Greg makes against the stereotypical architecture? We can now introduce verbs into the system. We can capture intent now (storing it still requires event sourcing, but you can implement event sourcing without doing CQRS) We can create a rich domain model (as opposed to an anemic domain model) Scalability is obviously a benefit that CQRS brings to the table, but like Greg says, very few of the systems we create truly need significant scalability Greg talks about the ability to scale your development efforts. He says CQRS allows you to split the system into 3 parts (Client, Domain/Commands, Reads) and assign 3 teams of developers to work on them in parallel; letting you scale your development efforts by 3x with nearly linear gains. But in the stereotypical architecture don’t you already have 2 separate modules that you can split your dev efforts between: The client that sends commands/queries and receives DTO’s, and the Domain which accepts commands/queries, and generates events/DTO’s. If this is true it’s not really a 3x scaling you achieve with CQRS but merely a 1.5x scaling which while great doesn’t sound nearly as dramatic (“I can do it with 10 devs in 12 months – let me hire 5 more and we can have it done in 8 months”). Making the Query side “stupid simple” such that you can assign junior developers (or even outsource it) sounds like a valid benefit, but I have some concerns over what you do with complex query-based logic/behavior. I’m going to go into more detail on this in a follow-up blog post shortly. He also seemed to focus on how “stupid-simple” it is doing queries against the de-normalized data store, but I imagine there is still significant complexity in the event handlers that interpret the events and apply them to the de-normalized tables. It sounds like Greg suggests that because we’re doing CQRS that allows us to apply Event Sourcing when we otherwise wouldn’t be able to (~33:30 in the video). I don’t believe this is true. I don’t see why you wouldn’t be able to apply Event Sourcing without separating out the Commands and Queries. The queries would just operate against the domain model instead of the database. But you’d still get the benefits of Event Sourcing. Without CQRS the queries would only be able to operate against the current state rather than the event history, but even in CQRS the domain behaviors can only operate against the current state and I don’t see that being a big limiting factor. If some query needs to operate against something that is not captured by the current state you would just have to update the domain model to capture that information (no different than if that statement were made about a Command under CQRS). Some of the benefits I do see being applicable are that your domain model might end up being simpler/smaller since it only needs to represent the state needed to process commands and not worry about the reads (like the Deactivate Inventory Item and associated comment example that Greg provides). And also commands that can be handled in a Transaction Script style manner by the command handler simply generating events and not touching the domain model. It also makes it easier for your senior developers to focus on the command behavior and ignore the queries, which is usually going to be a better use of their time. And of course scalability. If anybody out there has any thoughts on this and can help educate me further, please either leave a comment or feel free to get in touch with me via email:

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• SQLAuthority News – Why VoIP Service Providers Should Think About NuoDB’s Geo Distribution

  - by Pinal Dave

  You can always tell when someone’s showing off their cool, cutting edge comms technology. They tend to raise their voice a lot. Back in the day they’d announce their gadget leadership to the rest of the herd by shouting into their cellphone. Usually the message was no more urgent than “Hi, I’m on my cellphone!” Now the same types will loudly name-drop a different technology to the rest of the airport lounge. “I’m leveraging the wifi,” a fellow passenger bellowed, the other day, as we filtered through the departure gate. Nobody needed to know that, but the subtext was “look at me everybody”. You can tell the really advanced mobile user – they tend to whisper. Their handset has a microphone (how cool is that!) and they know how to use it. Sometimes these shouty public broadcasters aren’t even connected anyway because the database for their Voice over IP (VoIP) platform can’t cope. This will happen if they are using a traditional SQL model to try and cope with a phone network which has far flung offices and hundreds of mobile employees. That, like shouting into your phone, is just wrong on so many levels. What VoIP needs now is a single, logical database across multiple servers in different geographies. It needs to be updated in real-time and automatically scaled out during times of peak demand. A VoIP system should scale up to handle increased traffic, but just as importantly is must then go back down in the off peak hours. Try this with a MySQL database. It can’t scale easily enough, so it will keep your developers busy. They’ll have spent many hours trying to knit the different databases together. Traditional relational databases can possibly achieve this, at a price. Mind you, you could extend baked bean cans and string to every point on the network and that would be no less elegant. That’s not really following engineering principles though is it? Having said that, most telcos and VoIP systems use a separate, independent solution for each office location, which they link together – loosely.  The more office locations, the more complex and expensive the solution becomes and so the more you spend on maintenance. Ideally, you’d have a fluid system that can automatically shift its shape as the need arises. That’s the point of software isn’t it – it adapts. Otherwise, we might as well return to the old days. A MySQL system isn’t exactly baked bean cans attached by string, but it’s closer in spirit to the old many teethed mechanical beast that was employed in the first type of automated switchboard. NuoBD’s NewSQL is designed to be a single database that works across multiple servers, which can scale easily, and scale on demand. That’s one system that gives high connectivity but no latency, complexity or maintenance issues. MySQL works in some circumstances, but a period of growth isn’t one of them. So as a company moves forward, the MySQL database can’t keep pace. Data storage and data replication errors creep in. Soon the diaspora of offices becomes a problem. Your telephone system isn’t just distributed, it is literally all over the place. Though voice calls are often a software function, some of the old habits of telephony remain. When you call an engineer out, some of them will listen to what you’re asking for and announce that it cannot be done. This is what happens if you ask, say, database engineers familiar with Oracle or Microsoft to fulfill your wish for a low maintenance system built on a single, fluid, scalable database. No can do, they’d say. In fact, I heard one shouting something similar into his VoIP handset at the airport. “I can’t get on the network, Mac. I’m on MySQL.” You can download NuoDB from here. “NuoDB provides the ability to replicate data globally in real-time, which is not available with any other product offering,” states Weeks.  “That alone is remarkable and it works. I’ve seen it. I’ve used it.  I’ve tested it. The ability to deploy NuoDB removes a tremendous burden from our support and engineering teams.” Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: NuoDB

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