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• solution for an offline server

  - by dashmug

  I'm trying to setup a development server at work that will ideally be able to test drive a couple of projects in PHP, Rails, or Django (not always running at the same time). I develop the apps locally on a Mac and then I'll put the projects up on this server for testing with my actual users (non-techies) before deploying to a production server. My problem is that we have a very poor internet connection (almost negligible) at work and doing the usual apt-get/yum/ports (make, clean, install) processes for setting up servers always get their packages from online repositories somewhere. I know I could probably download the source and then compile them myself but that's going to be too much of a hassle for me. I'm thinking about two solutions: Plan A: Run a server VM on my Mac and then use this VM as the source repository for the offline server. I've read about Ubuntu's apt-proxy and it seems to be good enough though I haven't tried it yet. I'm not sure if this is possible but can I simply do apt-get install nginx --downloadonly so that the package and its dependencies will be downloaded into my VM and my server can use the VM as the source repo for apt-get? Plan B: Run a server VM on my Mac (which I can setup/update easily when I'm home) and then clone the VM to the offline development server. Maybe I should simply make the server a VM host so I can simply copy the VM over. I think this is okay for the first-time setup but subsequent updates will take too long (cloning the VM image). If I was working on Windows, I imagine it'd be easier because most services have an installer file that I can download and then run at the server. If you could suggest another way, it would be much appreciated. Update: From Michael Hampton's answer, I found a possible solution which is apt-cacher. I also found this page on Ubuntu's website. I wonder if there is a better tool than this one.

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• Parallel shell loops

  - by brubelsabs

  Hi, I want to process many files and since I've here a bunch of cores I want to do it in parallel: for i in *.myfiles; do do_something $i `derived_params $i` other_params; done I know of a Makefile solution but my commands needs the arguments out of the shell globbing list. What I found is: > function pwait() { > while [ $(jobs -p | wc -l) -ge $1 ]; do > sleep 1 > done > } > To use it, all one has to do is put & after the jobs and a pwait call, the parameter gives the number of parallel processes: > for i in *; do > do_something $i & > pwait 10 > done But this doesn't work very well, e.g. I tried it with e.g. a for loop converting many files but giving me error and left jobs undone. I can't belive that this isn't done yet since the discussion on zsh mailing list is so old by now. So do you know any better?

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• Why would the Apache parent process restart silently?

  - by miracle

  I run apache 2.2.9 with mpm prefork on debian lenny. Following http://httpd.apache.org/docs/2.2/mod/prefork.html, I would expect that there is one parent process, running as root and listening as configured, which would start child processes as defined by the Min/Max/etc. directives. I expect the children to be restarted as per MaxRequestsPerChild, but the parent process to stay put with one process id until I restart it manually. Out of a little paranoia, I started monitoring listening ports including process ids. I have a cron job every 20 minutes to run netstat -ap | grep LISTEN and diff the output. Sometimes (about once per day) I see a series of this: 8c8 < tcp6 0 0 [::]:www [::]:* LISTEN 6194/apache2 --- tcp6 0 0 [::]:www [::]:* LISTEN 6607/apache2 10c10 < tcp6 0 0 [::]:https [::]:* LISTEN 6194/apache2 --- tcp6 0 0 [::]:https [::]:* LISTEN 6607/apache2 Over a period of an hour or three, the parent would change its pid at least once every 20 minutes, without any explanation in the log files or any other hint that anything is going wrong. This is not what I expected. What am I missing?

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• java memory allocation under linux

  - by pstanton

  I'm running 4 java processes with the following command: java -Xmx256m -jar ... and the system has 8Gb memory under fedora 12. however it is apparently going into swap. how can that be if 4 x 256m = 1Gb ? EDIT: also, how can all 8Gb of memory be used with so little memory allocated to basically the only thing running? is it java not garbage collecting because the OS tells it it doesn't need to or what? TOP: top - 20:13:57 up 3:55, 6 users, load average: 1.99, 2.54, 2.67 Tasks: 251 total, 6 running, 245 sleeping, 0 stopped, 0 zombie Cpu(s): 50.1%us, 2.9%sy, 0.0%ni, 45.1%id, 1.1%wa, 0.0%hi, 0.8%si, 0.0%st Mem: 8252304k total, 8195552k used, 56752k free, 34356k buffers Swap: 10354680k total, 74044k used, 10280636k free, 6624148k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1948 xxxxxxxx 20 0 1624m 240m 4020 S 96.8 3.0 164:33.75 java 1927 xxxxxxxx 20 0 139m 31m 27m R 91.8 0.4 38:34.55 postgres 1929 xxxxxxxx 20 0 1624m 200m 3984 S 86.2 2.5 183:24.88 java 1969 xxxxxxxx 20 0 1624m 292m 3984 S 65.6 3.6 154:06.76 java 1987 xxxxxxxx 20 0 137m 29m 27m R 28.5 0.4 75:49.82 postgres 1581 root 20 0 159m 18m 4712 S 22.5 0.2 52:42.54 Xorg 2411 xxxxxxxx 20 0 309m 9748 4544 S 20.9 0.1 45:05.08 gnome-system-mo 1947 xxxxxxxx 20 0 137m 28m 27m S 13.3 0.4 44:46.04 postgres 1772 xxxxxxxx 20 0 135m 25m 25m S 4.0 0.3 1:09.14 postgres 1966 xxxxxxxx 20 0 137m 29m 27m S 3.0 0.4 64:27.09 postgres 1773 xxxxxxxx 20 0 135m 732 624 S 1.0 0.0 0:24.86 postgres 2464 xxxxxxxx 20 0 15028 1156 744 R 0.7 0.0 0:49.14 top 344 root 15 -5 0 0 0 S 0.3 0.0 0:02.26 kdmflush 1 root 20 0 4124 620 524 S 0.0 0.0 0:00.88 init 2 root 15 -5 0 0 0 S 0.0 0.0 0:00.00 kthreadd 3 root RT -5 0 0 0 S 0.0 0.0 0:00.00 migration/0 4 root 15 -5 0 0 0 S 0.0 0.0 0:00.04 ksoftirqd/0

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• VMware ESX Linux Guest Customization

  - by andyh_ky

  Hello, I am interested in deploying several RHEL 4 Update 8 virtual machines for creation of a test environment. Here are the steps I am taking: In off hours, P2V/V2V the production machines and convert them to templates Deploy the virtual machines with a customization specification that changes hostname, IP address I am interested in how these processes are done and if there are any options for further customization. Are the machines brought on the network when they are powered on, before they are reconfigured? Is there a potential IP address conflict? Is there an option to run additional scripts which reside on the guest as a part of the reconfiguration? For example, restoring an Oracle Database. This is an option with Windows guests and sysprep, but I have been unable to locate anything showing a RHEL equivalent. I am dealing with a multi tier application. The main issue I am attempting to mitigate is that the application servers reference database servers by hostname and in tnsnames files. I am interested in scripting the reconfiguration of the application in the deployment so that the app/db servers are pointing to the test environment. I am OK with placing the 'cleanup' script on the source and executing it after the machine has been brought up. I am interested in the automation of the script's execution post clone/boot, as well as if there could be an IP address conflict. (cross posted to VMTN's ESX 4 community)

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• Folder Sharing NTFS permissions with Share Permission

  - by Muhammad Adly

  i have a problem on my domain, the history starting from when i had a server with WIN 2008 r2 installed with the following roles installed on it (AD, DNS, DHCP, File). From 1 month i decided to install a new server 2008 r2 server to get (AD, DNS, DHCP) and leave the file server on the old one. i did the following exactly: 1) robocopy all my data on external HDD 2) Install a new server with 2008 r2 3) transfer all 5 roles to transfer the domain to the new server (MainDC) 4) issue (NETLOGON, SYSVOL) not transferred but i decided to reinitialize them again an now they are operating (MainDC) 5) re-create and re-configure a new GPOs and link it to my OUs 6) reinstall Old server operating system with a fresh installation of WIN 2008 R2 (FileServer) 7) join my domain with my domain credentials. the issue when i tried to share folder on \fileserver the permissions that i had set in sharing permissions are applied on the main shared folder and subfolders. the security settings are not applied. i.e. Say i'm sharing \fileserver\MainFolder with sharing permission for Authenticated Users that can read, so every one can read this main shared folder, if i set security permission for \fileserver\MainFolder\User1 that User1 can Read\Write\Modify. User1 can not perform this processes when accessing it from Network Share, i tried alot of steps from topics online get ownership for folder, remove inheritance from parent folder, applying changes for child objects, i tried also to construct a new folder structure but also the same issue, i tried another host PC, also i get the same issue.

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• Growing a small hosting company [closed]

  - by user2353007

  We currently have a few servers, 1 WHM VPS (2GB), 1 MS SQL VPS (2 GB), and 1 IIS VPS (2GB). The VPS servers are doing fine as far as uptime and response times but we would like to add the following features. 1) monitoring with load statistics 2) failover I have looked a Zabbix, Zenoss, Nagios, and a couple of other cloud solutions like monitor.us and watchdog from Zerigo. Ideally for the monitoring solution. Our current hosting company suggested we get a dedicated server or VPS and install load balancing software (not sure I like that idea). I've looked into Rackspace and Amazon load balancers which seem like the most feasible solutions for load balancers. Does anybody have any input on the monitoring and load balancing products I'm looking into? Monitoring should monitor uptime as well as give reports on memory usage, disk usage, processor usage, and which processes/websites/users are responsible for the load. It would be ideal if the load balancer worked with any IP. Not sure if either Rackspace or Amazon load balancers would allow load balancing with servers outside their datacenter. Thank you.

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• Determining how all memory is used in Windows Server 2008

  - by Mojah

  I have a Windows Server 2008 system, which has 12GB of RAM. If I list all processes in the Task Manager, and SUM() the memory of each process (Working Set, Memory (Private Working Set), Commit Size, ...), I never reach more than 4-5GB that should be "in use". However, task manager reports this server has 11GB in use via the "Performance" tab. I'm failing in determining where all that used RAM is going. It doesn't seem to be system cache, but I can not be sure. It might be a memory leak in one of the appliances, but I'm struggling to find out which one. The server's memory keeps filing up, and eventually forces us to reboot the device to clear it. I've been reading up on how RAM assignments work on Windows Server: RAM, Virtual Memory, Pagefile and all that stuff: http://support.microsoft.com/kb/2267427 What's the best way to measure? http://www.zdnet.com/blog/bott/windows-7-memory-usage-whats-the-best-way-to-measure/1786 Configure the file system cache in Windows: http://smallvoid.com/article/winnt-system-cache.html But I fear I'm stuck without ideas at the moment.

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• Allow more websocket connections

  - by Switz

  I want to load balance my node.js (DerbyJS to be specific) application on a basic Linode (512MB ram). It can probably take more than one process running at once. The querys/database does not concern me as I'm not doing anything intensive. The problem at the moment is that it can only handle up to ~40 websocket connections at once. I would love if I could get that number in the few hundred+ range. I anticipate a lot of traffic on launch due to the fact that it's a highly niche community with an engaged audience, but after it should be fine with just ~20-40 connections at once, which it handles perfectly as of now. I don't mind spending a bit of money for a week or two worth of running, but I also don't want to switch production environments. How can I test the process to see how many instances I am able to run on the box? Will increasing the number of processes increase the amount of websockets I can handle, or is that a limitation of the server's network? I have an old Macbook Pro running Linux sitting next to me that has 2GB ram and a 2.8 Dual Core Processor. Could I use this to handle some of the extra load? I could probably load balance with nginx to its IP. I'm on a FiOS home network. If you have any suggestions, I'd really appreciate it. Thanks

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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 =&gt; 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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• Why should you choose Oracle WebLogic 12c instead of JBoss EAP 6?

  - by Ricardo Ferreira

  In this post, I will cover some technical differences between Oracle WebLogic 12c and JBoss EAP 6, which was released a couple days ago from Red Hat. This article claims to help you in the evaluation of key points that you should consider when choosing for an Java EE application server. In the following sections, I will present to you some important aspects that most customers ask us when they are seriously evaluating for an middleware infrastructure, specially if you are considering JBoss for some reason. I would suggest that you keep the following question in mind while you are reading the points: "Why should I choose JBoss instead of WebLogic?" 1) Multi Datacenter Deployment and Clustering - D/R ("Disaster & Recovery") architecture support is embedded on the WebLogic Server 12c product. JBoss EAP 6 on the other hand has no direct D/R support included, Red Hat relies on third-part tools with higher prices. When you consider a middleware solution to host your business critical application, you should worry with every architectural aspect that are related with the solution. Fail-over support is one little aspect of a truly reliable solution. If you do not worry about D/R, your solution will not be reliable. Having said that, with Red Hat and JBoss EAP 6, you have this extra cost that will increase considerably the total cost of ownership of the solution. As we commonly hear from analysts, open-source are not so cheaper when you start seeing the big picture. - WebLogic Server 12c supports advanced LAN clustering, detection of death servers and have a common alert framework. JBoss EAP 6 on the other hand has limited LAN clustering support with no server death detection. They do not generate any alerts when servers goes down (only if you buy JBoss ON which is a separated technology, but until now does not support JBoss EAP 6) and manual intervention are required when servers goes down. In most cases, admin people must rely on "kill -9", "tail -f someFile.log" and "ps ax | grep java" commands to manage failures and clustering anomalies. - WebLogic Server 12c supports the concept of Node Manager, which is a separated process that runs on the physical | virtual servers that allows extend the administration of the cluster to WebLogic managed servers that are often distributed across multiple machines and geographic locations. JBoss EAP 6 on the other hand has no equivalent technology. Whole server instances must be managed individually. - WebLogic Server 12c Node Manager supports Coherence to boost performance when managing servers. JBoss EAP 6 on the other hand has no similar technology. There is no way to coordinate JBoss and infiniband instances provided by JBoss using high throughput and low latency protocols like InfiniBand. The Node Manager feature also allows another very important feature that JBoss EAP lacks: secure the administration. When using WebLogic Node Manager, all the administration tasks are sent to the managed servers in a secure tunel protected by a certificate, which means that the transport layer that separates the WebLogic administration console from the managed servers are secured by SSL. - WebLogic Server 12c are now integrated with OTD ("Oracle Traffic Director") which is a web server technology derived from the former Sun iPlanet Web Server. This software complements the web server support offered by OHS ("Oracle HTTP Server"). Using OTD, WebLogic instances are load-balanced by a high powerful software that knows how to handle SDP ("Socket Direct Protocol") over InfiniBand, which boost performance when used with engineered systems technologies like Oracle Exalogic Elastic Cloud. JBoss EAP 6 on the other hand only offers support to Apache Web Server with custom modules created to deal with JBoss clusters, but only across standard TCP/IP networks.  2) Application and Runtime Diagnostics - WebLogic Server 12c have diagnostics capabilities embedded on the server called WLDF ("WebLogic Diagnostic Framework") so there is no need to rely on third-part tools. JBoss EAP 6 on the other hand has no diagnostics capabilities. Their only diagnostics tool is the log generated by the application server. Admin people are encouraged to analyse thousands of log lines to find out what is going on. - WebLogic Server 12c complement WLDF with JRockit MC ("Mission Control"), which provides to administrators and developers a complete insight about the JVM performance, behavior and possible bottlenecks. WebLogic Server 12c also have an classloader analysis tool embedded, and even a log analyzer tool that enables administrators and developers to view logs of multiple servers at the same time. JBoss EAP 6 on the other hand relies on third-part tools to do something similar. Again, only log searching are offered to find out whats going on. - WebLogic Server 12c offers end-to-end traceability and monitoring available through Oracle EM ("Enterprise Manager"), including monitoring of business transactions that flows through web servers, ESBs, application servers and database servers, all of this with high deep JVM analysis and diagnostics. JBoss EAP 6 on the other hand, even using JBoss ON ("Operations Network"), which is a separated technology, does not support those features. Red Hat relies on third-part tools to provide direct Oracle database traceability across JVMs. One of those tools are Oracle EM for non-Oracle middleware that manage JBoss, Tomcat, Websphere and IIS transparently. - WebLogic Server 12c with their JRockit support offers a tool called JRockit Flight Recorder, which can give developers a complete visibility of a certain period of application production monitoring with zero extra overhead. This automatic recording allows you to deep analyse threads latency, memory leaks, thread contention, resource utilization, stack overflow damages and GC ("Garbage Collection") cycles, to observe in real time stop-the-world phenomenons, generational, reference count and parallel collects and mutator threads analysis. JBoss EAP 6 don't even dream to support something similar, even because they don't have their own JVM. 3) Application Server Administration - WebLogic Server 12c offers a complete administration console complemented with scripting and macro-like recording capabilities. A single WebLogic console can managed up to hundreds of WebLogic servers belonging to the same domain. JBoss EAP 6 on the other hand has a limited console and provides a XML centric administration. JBoss, after ten years, started the development of a rudimentary centralized administration that still leave a lot of administration tasks aside, so admin people and developers must touch scripts and XML configuration files for most advanced and even simple administration tasks. This lead applications to error prone and risky deployments. Even using JBoss ON, JBoss EAP are not able to offer decent administration features for admin people which must be high skilled in JBoss internal architecture and its managing capabilities. - Oracle EM is available to manage multiple domains, databases, application servers, operating systems and virtualization, with a complete end-to-end visibility. JBoss ON does not provide management capabilities across the complete architecture, only basic monitoring. Even deployment must be done aside JBoss ON which does no integrate well with others softwares than JBoss. Until now, JBoss ON does not supports JBoss EAP 6, so even their minimal support for JBoss are not available for JBoss EAP 6 leaving customers uncovered and subject to high skilled JBoss admin people. - WebLogic Server 12c has the same administration model whatever is the topology selected by the customer. JBoss EAP 6 on the other hand differentiates between two operational models: standalone-mode and domain-mode, that are not consistent with each other. Depending on the mode used, the administration skill is different. - WebLogic Server 12c has no point-of-failures processes, and it does not need to define any specialized server. Domain model in WebLogic is available for years (at least ten years or more) and is production proven. JBoss EAP 6 on the other hand needs special processes to garantee JBoss integrity, the PC ("Process-Controller") and the HC ("Host-Controller"). Different from WebLogic, the domain model in JBoss is quite new (one year at tops) of maturity, and need to mature considerably until start doing things like WebLogic domain model does. - WebLogic Server 12c supports parallel deployment model which enables some artifacts being deployed at the same time. JBoss EAP 6 on the other hand does not have any similar feature. Every deployment are done atomically in the containers. This means that if you have a huge EAR (an EAR of 120 MB of size for instance) and deploy onto JBoss EAP 6, this EAR will take some minutes in order to starting accept thread requests. The same EAR deployed onto WebLogic Server 12c will reduce the deployment time at least in 2X compared to JBoss. 4) Support and Upgrades - WebLogic Server 12c has patch management available. JBoss EAP 6 on the other hand has no patch management available, each JBoss EAP instance should be patched manually. To achieve such feature, you need to buy a separated technology called JBoss ON ("Operations Network") that manage this type of stuff. But until now, JBoss ON does not support JBoss EAP 6 so, in practice, JBoss EAP 6 does not have this feature. - WebLogic Server 12c supports previuous WebLogic domains without any reconfiguration since its kernel is robust and mature since its creation in 1995. JBoss EAP 6 on the other hand has a proven lack of supportability between JBoss AS 4, 5, 6 and 7. Different kernels and messaging engines were implemented in JBoss stack in the last five years reveling their incapacity to create a well architected and proven middleware technology. - WebLogic Server 12c has patch prescription based on customer configuration. JBoss EAP 6 on the other hand has no such capability. People need to create ticket supports and have their installations revised by Red Hat support guys to gain some patch prescription from them. - Oracle WebLogic Server independent of the version has 8 years of support of new patches and has lifetime release of existing patches beyond that. JBoss EAP 6 on the other hand provides patches for a specific application server version up to 5 years after the release date. JBoss EAP 4 and previous versions had only 4 years. A good question that Red Hat will argue to answer is: "what happens when you find issues after year 5"?  5) RAC ("Real Application Clusters") Support - WebLogic Server 12c ships with a specific JDBC driver to leverage Oracle RAC clustering capabilities (Fast-Application-Notification, Transaction Affinity, Fast-Connection-Failover, etc). Oracle JDBC thin driver are also available. JBoss EAP 6 on the other hand ships only the standard Oracle JDBC thin driver. Load balancing with Oracle RAC are not supported. Manual intervention in case of planned or unplanned RAC downtime are necessary. In JBoss EAP 6, situation does not reestablish automatically after downtime. - WebLogic Server 12c has a feature called Active GridLink for Oracle RAC which provides up to 3X performance on OLTP applications. This seamless integration between WebLogic and Oracle database enable more value added to critical business applications leveraging their investments in Oracle database technology and Oracle middleware. JBoss EAP 6 on the other hand has no performance gains at all, even when admin people implement some kind of connection-pooling tuning. - WebLogic Server 12c also supports transaction and web session affinity to the Oracle RAC, which provides aditional gains of performance. This is particularly interesting if you are creating a reliable solution that are distributed not only in an LAN cluster, but into a different data center. JBoss EAP 6 on the other hand has no such support. 6) Standards and Technology Support - WebLogic Server 12c is fully Java EE 6 compatible and production ready since december of 2011. JBoss EAP 6 on the other hand became fully compatible with Java EE 6 only in the community version after three months, and production ready only in a few days considering that this article was written in June of 2012. Red Hat says that they are the masters of innovation and technology proliferation, but compared with Oracle and even other proprietary vendors like IBM, they historically speaking are lazy to deliver the most newest technologies and standards adherence. - Oracle is the steward of Java, driving innovation into the platform from commercial and open-source vendors. Red Hat on the other hand does not have its own JVM and relies on third-part JVMs to complete their application server offer. 95% of Red Hat customers are using Oracle HotSpot as JVM, which means that without Oracle involvement, their support are limited exclusively to the application server layer and we all know that most problems are happens in the JVM layer. - WebLogic Server 12c supports natively JDK 7, which empower developers to explore the maximum of the Java platform productivity when writing code. This feature differentiate WebLogic from others application servers (except GlassFish that are also managed by Oracle) because the usage of JDK 7 introduce such remarkable productivity features like the "try-with-resources" enhancement, catching multiple exceptions with one try block, Strings in the switch statements, JVM improvements in terms of JDBC, I/O, networking, security, concurrency and of course, the most important feature of Java 7: native support for multiple non-Java languages. More features regarding JDK 7 can be found here. JBoss EAP 6 on the other hand does not support JDK 7 officially, they comment in their community version that "Java SE 7 can be used with JBoss 7" which does not gives you any guarantees of enterprise support for JDK 7. - Oracle WebLogic Server 12c supports integration with Spring framework allowing Spring applications to use WebLogic special transaction manager, exposing bean interfaces to WebLogic MBeans to take advantage of all WebLogic monitoring and administration advantages. JBoss EAP 6 on the other hand has no special integration with Spring. In fact, Red Hat offers a suspicious package called "JBoss Web Platform" that in theory supports Spring, but in practice this package does not offers any special integration. It is just a facility for Red Hat customers to have support from both JBoss and Spring technology using the same customer support. 7) Lightweight Development - Oracle WebLogic Server 12c and Oracle GlassFish are completely integrated and can share applications without any modifications. Starting with the 12c version, WebLogic now understands natively GlassFish deployment descriptors and specific configurations in order to offer you a truly and reliable migration path from a community Java EE application server to a enterprise middleware product like WebLogic. JBoss EAP 6 on the other hand has no support to natively reuse an existing (or still in development) application from JBoss AS community server. Users of JBoss suffer of critical issues during deployment time that includes: changing the libraries and dependencies of the application, patching the DTD or XSD deployment descriptors, refactoring of the application layers due classloading issues and anomalies, rebuilding of persistence, business and web layers due issues with "usage of the certified version of an certain dependency" or "frameworks that Red Hat potentially does not recommend" etc. If you have the culture or enterprise IT directive of developing Java EE applications using community middleware to in a certain future, transition to enterprise (supported by a vendor) middleware, Oracle WebLogic plus Oracle GlassFish offers you a more sustainable solution. - WebLogic Server 12c has a very light ZIP distribution (less than 165 MB). JBoss EAP 6 ZIP size is around 130 MB, together with JBoss ON you have more 100 MB resulting in a higher download footprint. This is particularly interesting if you plan to use automated setup of application server instances (for example, to rapidly setup a development or staging environment) using Maven or Hudson. - WebLogic Server 12c has a complete integration with Maven allowing developers to setup WebLogic domains with few commands. Tasks like downloading WebLogic, installation, domain creation, data sources deployment are completely integrated. JBoss EAP 6 on the other hand has a limited offer integration with those tools.  - WebLogic Server 12c has a startup mode called WLX that turns-off EJB, JMS and JCA containers leaving enabled only the web container with Java EE 6 web profile. JBoss EAP 6 on the other hand has no such feature, you need to disable manually the containers that you do not want to use. - WebLogic Server 12c supports fastswap, which enables you to change classes without redeployment. This is particularly interesting if you are developing patches for the application that is already deployed and you do not want to redeploy the entire application. This is the same behavior that most application servers offers to JSP pages, but with WebLogic Server 12c, you have the same feature for Java classes in general. JBoss EAP 6 on the other hand has no such support. Even JBoss EAP 5 does not support this until now. 8) JMS and Messaging - WebLogic Server 12c has a proven and high scalable JMS implementation since its initial release in 1995. JBoss EAP 6 on the other hand has a still immature technology called HornetQ, which was introduced in JBoss EAP 5 replacing everything that was implemented in the previous versions. Red Hat loves to introduce new technologies across JBoss versions, playing around with customers and their investments. And when they are asked about why they have changed the implementation and caused such a mess, their answer is always: "the previous implementation was inadequate and not aligned with the community strategy so we are creating a new a improved one". This Red Hat practice leads to uncomfortable investments that in a near future (sometimes less than a year) will be affected in someway. - WebLogic Server 12c has troubleshooting and monitoring features included on the WebLogic console and WLDF. JBoss EAP 6 on the other hand has no direct monitoring on the console, activity is reflected only on the logs, no debug logs available in case of JMS issues. - WebLogic Server 12c has extremely good performance and scalability. JBoss EAP 6 on the other hand has a JMS storage mechanism relying on Oracle database or MySQL. This means that if an issue in production happens and Red Hat affirms that an performance issue is happening due to database problems, they will not support you on the performance issue. They will orient you to call Oracle instead. - WebLogic Server 12c supports messaging enterprise features like SAF ("Store and Forward"), Distributed Queues/Topics and Foreign JMS providers support that leverage JMS implementations without compromise developer code making things completely transparent. JBoss EAP 6 on the other hand do not even dream to support such features. 9) Caching and Grid - Coherence, which is the leading and most mature data grid technology from Oracle, is available since early 2000 and was integrated with WebLogic in 2009. Coherence and WebLogic clusters can be both managed from WebLogic administrative console. Even Node Manager supports Coherence. JBoss on the other hand discontinued JBoss Cache, which was their caching implementation just like they did with the messaging implementation (JBossMQ) which was a issue for long term customers. JBoss EAP 6 ships InfiniSpan version 1.0 which is immature and lack a proven record of successful cases and reliability. - WebLogic Server 12c has a feature called ActiveCache which uses Coherence to, without any code changes, replicate HTTP sessions from both WebLogic and other application servers like JBoss, Tomcat, Websphere, GlassFish and even Microsoft IIS. JBoss EAP 6 on the other hand does have such support and even when they do in the future, they probably will support only their own application server. - Coherence can be used to manage both L1 and L2 cache levels, providing support to Oracle TopLink and others JPA compliant implementations, even Hibernate. JBoss EAP 6 and Infinispan on the other hand supports only Hibernate. And most important of all: Infinispan does not have any successful case of L1 or L2 caching level support using Hibernate, which lead us to reflect about its viability. 10) Performance - WebLogic Server 12c is certified with Oracle Exalogic Elastic Cloud and can run unchanged applications at this engineered system. This approach can benefit customers from Exalogic optimization's of both kernel and JVM layers to boost performance in terms of 10X for web, OLTP, JMS and grid applications. JBoss EAP 6 on the other hand has no investment on engineered systems: customers do not have the choice to deploy on a Java ultra fast system if their project becomes relevant and performance issues are detected. - WebLogic Server 12c maintains a performance gain across each new release: starting on WebLogic 5.1, the overall performance gain has been close to 4X, which close to a 20% gain release by release. JBoss on the other hand does not provide SPECJAppServer or SPECJEnterprise performance benchmarks. Their so called "performance gains" remains hidden in their customer environments, which lead us to think if it is true or not since we will never get access to those environments. - WebLogic Server 12c has industry performance benchmarks with submissions across platforms and configurations leading SPECJ. Oracle WebLogic leads SPECJAppServer performance in multiple categories, fitting all customer topologies like: dual-node, single-node, multi-node and multi-node with RAC. JBoss... again, does not provide any SPECJAppServer performance benchmarks. - WebLogic Server 12c has a feature called work manager which allows your application to embrace new performance levels based on critical resource utilization of the CPUs usage. Work managers prioritizes work and allocates threads based on an execution model that takes into account administrator-defined parameters and actual run-time performance and throughput. JBoss EAP 6 on the other hand has no compared feature and probably they never will. Not supporting such feature like work managers, JBoss EAP 6 forces admin people and specially developers to uncover performance gains in a intrusive way, rewriting the code and doing performance refactorings. 11) Professional Services Support - WebLogic Server 12c and any other technology sold by Oracle give customers the possibility of hire OCS ("Oracle Consulting Services") to manage critical scenarios, deployment assistance of new applications, high skilled consultancy of architecture, best practices and people allocation together with customer teams. All OCS services are available without any restrictions, having the customer bought software from Oracle or just starting their implementation before any acquisition. JBoss EAP 6 or Red Hat to be more specifically, only offers professional services if you buy subscriptions from them. If you are developing a new critical application for your business and need the help of Red Hat for a serious issue or architecture decision, they will probably say: "OK... I can help you but after you buy subscriptions from me". Red Hat also does not allows their professional services consultants to manage environments that uses community based software. They will probably force you to first buy a subscription, download their "enterprise" version and them, optionally hire their consultants. - Oracle provides you our university to educate your team into our technologies, including of course specialized trainings of WebLogic application server. At any time and location, you can hire Oracle to train your team so you get trustful knowledge according to your specific needs. Certifications for the products are also available if your technical people desire to differentiate themselves as professionals. Red Hat on the other hand have a limited pool of resources to train your team in their technologies. Basically they are selling training and certification for RHEL ("Red Hat Enterprise Linux") but if you demand more specialized training in JBoss middleware, they will probably connect you to some "certified" partner localized training since they are apparently discontinuing their education center, at least here in Brazil. They were not able to reproduce their success with RHEL education to their middleware division since they need first sell the subscriptions to after gives you specialized training. And again, they only offer you specialized training based on their enterprise version (EAP in the case of JBoss) which means that the courses will be a quite outdated. There are reports of developers that took official training's from Red Hat at this year (2012) and in a certain JBoss advanced course, Red Hat supposedly covered JBossMQ as the messaging subsystem, and even the printed material provided was based on JBossMQ since the training was created for JBoss EAP 4.3. 12) Encouraging Transparency without Ulterior Motives - WebLogic Server 12c like any other software from Oracle can be downloaded any time from anywhere, you should only possess an OTN ("Oracle Technology Network") credential and you can download any enterprise software how many times you want. And is not some kind of "trial" version. It is the official binaries that will be running for ever in your data center. Oracle does not encourages the usage of "specific versions" of our software. The binaries you buy from Oracle are the same binaries anyone in the world could download and use for testing and personal education. JBoss EAP 6 on the other hand are not available for download unless you buy a subscription and get access to the Red Hat enterprise repositories. If you need to test, learn or just start creating your application using Red Hat's middleware software, you should download it from the community website. You are not allowed to download the enterprise version that, according to Red Hat are more secure, reliable and robust. But no one of us want to start the development of a software with an unsecured, unreliable and not scalable middleware right? So what you do? You are "invited" by Red Hat to buy subscriptions from them to get access to the "cool" version of the software. - WebLogic Server 12c prices are publicly available in the Oracle website. If you want to know right now how much WebLogic will cost to your organization, just click here and get access to our price list. In the case of WebLogic, check out the "US Oracle Technology Commercial Price List". Oracle also encourages you to get in touch with a sales representative to discuss discounts that would make possible the investment into our technology. But you are not required to do this, only if you are interested in buying our technology or maybe you want to discuss some discount scenarios. JBoss EAP 6 on the other hand does not have its cost publicly available in Red Hat's website or in any other media, at least is not so easy to get such information. The only link you will possibly find in their website is a "Contact a Sales Representative" link. This is not a very good relationship between an customer and an vendor. This is not an example of transparency, mainly when the software are sold as open. In this situations, customers expects to see the software prices publicly available, so they can have the chance to decide, based on the existing features of the software, if the cost is fair or not. Conclusion Oracle WebLogic is the most mature, secure, reliable and scalable Java EE application server of the market, and have a proven record of success around the globe to prove it's majority. Don't lose the chance to discover today how WebLogic could fit your needs and sustain your global IT middleware strategy, no matter if your strategy are completely based on the Cloud or not.

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• Know more about Cache Buffer Handle

  - by Liu Maclean(???)

  ??????«latch free:cache buffer handles???SQL????»?????cache buffer handle latch?????,?????????: “?????pin?buffer header???????buffer handle,??buffer handle?????????cache buffer handles?,??????cache buffer handles??????,???????cache???buffer handles,?????(reserved set)?????????????_db_handles_cached(???5)???,?????????????????SQL??????????????????????,????pin??????,????????handle,?????????5?cached buffer handles???handle????????????????,Oracle?????????????????pin?”????“?buffer,????????????????handle???db_block_buffers/processes,????_cursor_db_buffers_pinned???????cache buffer handles?????,??????,????????????SQL,????cache?buffer handles?????????,??????????????,???????????/?????” ????T.ASKMACLEAN.COM????,??????cache Buffer handle?????: cache buffer handle ??: ------------------------------ | Buffer state object | ------------------------------ | Place to hang the buffer | ------------------------------ | Consistent Get? | ------------------------------ | Proc Owning SO | ------------------------------ | Flags(RIR) | ------------------------------ ???? cache buffer handle SO: 70000046fdfe530, type: 24, owner: 70000041b018630, flag: INIT/-/-/0×00(buffer) (CR) PR: 70000048e92d148 FLG: 0×500000lock rls: 0, class bit: 0kcbbfbp: [BH: 7000001c7f069b0, LINK: 70000046fdfe570]where: kdswh02: kdsgrp, why: 0BH (7000001c7f069b0) file#: 12 rdba: 0×03061612 (12/398866) class: 1 ba: 7000001c70ee000set: 75 blksize: 8192 bsi: 0 set-flg: 0 pwbcnt: 0dbwrid: 2 obj: 66209 objn: 48710 tsn: 6 afn: 12hash: [700000485f12138,700000485f12138] lru: [70000025af67790,700000132f69ee0]lru-flags: hot_bufferckptq: [NULL] fileq: [NULL] objq: [700000114f5dd10,70000028bf5d620]use: [70000046fdfe570,70000046fdfe570] wait: [NULL]st: SCURRENT md: SHR tch: 0flags: affinity_lockLRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]where: kdswh02: kdsgrp, why: 0 # Example:#   (buffer) (CR) PR: 37290 FLG:    0#   kcbbfbp    : [BH: befd8, LINK: 7836c] (WAITING) Buffer handle (X$KCBBF) kernel cache, buffer buffer_handles Query x$kcbbf  – lists all the buffer handles ???? _db_handles             System-wide simultaneous buffer operations ,no of buffer handles_db_handles_cached      Buffer handles cached each process , no of processes  default 5_cursor_db_buffers_pinned  additional number of buffers a cursor can pin at once_session_kept_cursor_pins       Number of cursors pins to keep in a session When a buffer is pinned it is attached to buffer state object. ??? ???????? cache buffer handles latch ? buffer pin???: SESSION A : SQL> select * from v$version; BANNER ---------------------------------------------------------------- Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bi PL/SQL Release 10.2.0.5.0 - Production CORE    10.2.0.5.0      Production TNS for Linux: Version 10.2.0.5.0 - Production NLSRTL Version 10.2.0.5.0 - Production SQL> create table test_cbc_handle(t1 int); Table created. SQL> insert into test_cbc_handle values(1); 1 row created. SQL> commit; Commit complete. SQL> select rowid from test_cbc_handle; ROWID ------------------ AAANO6AABAAAQZSAAA SQL> select * from test_cbc_handle where rowid='AAANO6AABAAAQZSAAA';         T1 ----------          1 SQL> select addr,name from v$latch_parent where name='cache buffer handles'; ADDR             NAME ---------------- -------------------------------------------------- 00000000600140A8 cache buffer handles SQL> select to_number('00000000600140A8','xxxxxxxxxxxxxxxxxxxx') from dual; TO_NUMBER('00000000600140A8','XXXXXXXXXXXXXXXXXXXX') ----------------------------------------------------                                           1610694824 ??cache buffer handles????parent latch ??? child latch ???SESSION A hold ??????cache buffer handles parent latch ???? oradebug call kslgetl ??, kslgetl?oracle??get latch??? SQL> oradebug setmypid; Statement processed. SQL> oradebug call kslgetl 1610694824 1; Function returned 1 ?????SESSION B ???: SQL> select * from v$latchholder;        PID        SID LADDR            NAME                                                                   GETS ---------- ---------- ---------------- ---------------------------------------------------------------- ----------         15        141 00000000600140A8 cache buffer handles                                                    119 cache buffer handles latch ???session A hold??,????????acquire cache buffer handle latch SQL> select * from test_cbc_handle where rowid='AAANO6AABAAAQZSAAA';         T1 ----------          1 ?????Server Process?????? read buffer, ????????"_db_handles_cached", ??process?cache 5? cache buffer handle ??"_db_handles_cached"=0,?process????5????cache buffer handle , ???? process ???pin buffer,???hold cache buffer handle latch??????cache buffer handle SQL> alter system set "_db_handles_cached"=0 scope=spfile; System altered. ????? shutdown immediate; startup; session A: SQL> oradebug setmypid; Statement processed. SQL> oradebug call kslgetl 1610694824 1; Function returned 1 session B: select * from test_cbc_handle where rowid='AAANO6AABAAAQZSAAA'; session B hang!! WHY? SQL> oradebug setmypid; Statement processed. SQL> oradebug dump systemstate 266; Statement processed.   SO: 0x11b30b7b0, type: 2, owner: (nil), flag: INIT/-/-/0x00   (process) Oracle pid=22, calls cur/top: (nil)/0x11b453c38, flag: (0) -             int error: 0, call error: 0, sess error: 0, txn error 0   (post info) last post received: 0 0 0               last post received-location: No post               last process to post me: none               last post sent: 0 0 0               last post sent-location: No post               last process posted by me: none     (latch info) wait_event=0 bits=8       holding    (efd=4) 600140a8 cache buffer handles level=3   SO: 0x11b305810, type: 2, owner: (nil), flag: INIT/-/-/0x00   (process) Oracle pid=10, calls cur/top: 0x11b455ac0/0x11b450a58, flag: (0) -             int error: 0, call error: 0, sess error: 0, txn error 0   (post info) last post received: 0 0 0               last post received-location: No post               last process to post me: none               last post sent: 0 0 0               last post sent-location: No post               last process posted by me: none     (latch info) wait_event=0 bits=2         Location from where call was made: kcbzgs:       waiting for 600140a8 cache buffer handles level=3 FBD93353:000019F0    10   162 10005   1 KSL WAIT BEG [latch: cache buffer handles] 1610694824/0x600140a8 125/0x7d 0/0x0 FF936584:00002761    10   144 10005   1 KSL WAIT BEG [latch: cache buffer handles] 1610694824/0x600140a8 125/0x7d 0/0x0 PID=22 holding ??cache buffer handles latch PID=10 ?? cache buffer handles latch, ????"_db_handles_cached"=0 ?? process??????cache buffer handles ??systemstate???? kcbbfbp cache buffer handle??, ?? "_db_handles_cached"=0 ? cache buffer handles latch?hold ?? ????cache buffer handles latch , ??? buffer?pin?????????? session A exit session B: SQL> select * from v$latchholder; no rows selected SQL> insert into test_cbc_handle values(2); 1 row created. SQL> commit; Commit complete. SQL> SQL> select t1,rowid from test_cbc_handle;         T1 ROWID ---------- ------------------          1 AAANPAAABAAAQZSAAA          2 AAANPAAABAAAQZSAAB SQL> select spid,pid from v$process where addr = ( select paddr from v$session where sid=(select distinct sid from v$mystat)); SPID                PID ------------ ---------- 19251                10 ? GDB ? SPID=19215 ?debug , ?? kcbrls ????breakpoint ??? ????release buffer [oracle@vrh8 ~]$ gdb $ORACLE_HOME/bin/oracle 19251 GNU gdb (GDB) Red Hat Enterprise Linux (7.0.1-37.el5) Copyright (C) 2009 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.  Type "show copying" and "show warranty" for details. This GDB was configured as "x86_64-redhat-linux-gnu". For bug reporting instructions, please see: <http://www.gnu.org/software/gdb/bugs/>... Reading symbols from /s01/oracle/product/10.2.0.5/db_1/bin/oracle...(no debugging symbols found)...done. Attaching to program: /s01/oracle/product/10.2.0.5/db_1/bin/oracle, process 19251 Reading symbols from /s01/oracle/product/10.2.0.5/db_1/lib/libskgxp10.so...(no debugging symbols found)...done. Loaded symbols for /s01/oracle/product/10.2.0.5/db_1/lib/libskgxp10.so Reading symbols from /s01/oracle/product/10.2.0.5/db_1/lib/libhasgen10.so...(no debugging symbols found)...done. Loaded symbols for /s01/oracle/product/10.2.0.5/db_1/lib/libhasgen10.so Reading symbols from /s01/oracle/product/10.2.0.5/db_1/lib/libskgxn2.so...(no debugging symbols found)...done. Loaded symbols for /s01/oracle/product/10.2.0.5/db_1/lib/libskgxn2.so Reading symbols from /s01/oracle/product/10.2.0.5/db_1/lib/libocr10.so...(no debugging symbols found)...done. Loaded symbols for /s01/oracle/product/10.2.0.5/db_1/lib/libocr10.so Reading symbols from /s01/oracle/product/10.2.0.5/db_1/lib/libocrb10.so...(no debugging symbols found)...done. Loaded symbols for /s01/oracle/product/10.2.0.5/db_1/lib/libocrb10.so Reading symbols from /s01/oracle/product/10.2.0.5/db_1/lib/libocrutl10.so...(no debugging symbols found)...done. Loaded symbols for /s01/oracle/product/10.2.0.5/db_1/lib/libocrutl10.so Reading symbols from /s01/oracle/product/10.2.0.5/db_1/lib/libjox10.so...(no debugging symbols found)...done. Loaded symbols for /s01/oracle/product/10.2.0.5/db_1/lib/libjox10.so Reading symbols from /s01/oracle/product/10.2.0.5/db_1/lib/libclsra10.so...(no debugging symbols found)...done. Loaded symbols for /s01/oracle/product/10.2.0.5/db_1/lib/libclsra10.so Reading symbols from /s01/oracle/product/10.2.0.5/db_1/lib/libdbcfg10.so...(no debugging symbols found)...done. Loaded symbols for /s01/oracle/product/10.2.0.5/db_1/lib/libdbcfg10.so Reading symbols from /s01/oracle/product/10.2.0.5/db_1/lib/libnnz10.so...(no debugging symbols found)...done. Loaded symbols for /s01/oracle/product/10.2.0.5/db_1/lib/libnnz10.so Reading symbols from /usr/lib64/libaio.so.1...(no debugging symbols found)...done. Loaded symbols for /usr/lib64/libaio.so.1 Reading symbols from /lib64/libdl.so.2...(no debugging symbols found)...done. Loaded symbols for /lib64/libdl.so.2 Reading symbols from /lib64/libm.so.6...(no debugging symbols found)...done. Loaded symbols for /lib64/libm.so.6 Reading symbols from /lib64/libpthread.so.0...(no debugging symbols found)...done. [Thread debugging using libthread_db enabled] Loaded symbols for /lib64/libpthread.so.0 Reading symbols from /lib64/libnsl.so.1...(no debugging symbols found)...done. Loaded symbols for /lib64/libnsl.so.1 Reading symbols from /lib64/libc.so.6...(no debugging symbols found)...done. Loaded symbols for /lib64/libc.so.6 Reading symbols from /lib64/ld-linux-x86-64.so.2...(no debugging symbols found)...done. Loaded symbols for /lib64/ld-linux-x86-64.so.2 Reading symbols from /lib64/libnss_files.so.2...(no debugging symbols found)...done. Loaded symbols for /lib64/libnss_files.so.2 0x00000035c000d940 in __read_nocancel () from /lib64/libpthread.so.0 (gdb) break kcbrls Breakpoint 1 at 0x10e5d24 session B: select * from test_cbc_handle where rowid='AAANPAAABAAAQZSAAA'; select hang !! GDB (gdb) c Continuing. Breakpoint 1, 0x00000000010e5d24 in kcbrls () (gdb) bt #0  0x00000000010e5d24 in kcbrls () #1  0x0000000002e87d25 in qertbFetchByUserRowID () #2  0x00000000030c62b8 in opifch2 () #3  0x00000000032327f0 in kpoal8 () #4  0x00000000013b7c10 in opiodr () #5  0x0000000003c3c9da in ttcpip () #6  0x00000000013b3144 in opitsk () #7  0x00000000013b60ec in opiino () #8  0x00000000013b7c10 in opiodr () #9  0x00000000013a92f8 in opidrv () #10 0x0000000001fa3936 in sou2o () #11 0x000000000072d40b in opimai_real () #12 0x000000000072d35c in main () SQL> oradebug setmypid; Statement processed. SQL> oradebug dump systemstate 266; Statement processed. ?????? kcbbfbp buffer cache handle ?  SO state object ? BH BUFFER HEADER  link???     ----------------------------------------     SO: 0x11b452348, type: 3, owner: 0x11b305810, flag: INIT/-/-/0x00     (call) sess: cur 11b41bd18, rec 0, usr 11b41bd18; depth: 0       ----------------------------------------       SO: 0x1182dc750, type: 24, owner: 0x11b452348, flag: INIT/-/-/0x00       (buffer) (CR) PR: 0x11b305810 FLG: 0x108000       class bit: (nil)       kcbbfbp: [BH: 0xf2fc69f8, LINK: 0x1182dc790]       where: kdswh05: kdsgrp, why: 0       BH (0xf2fc69f8) file#: 1 rdba: 0x00410652 (1/67154) class: 1 ba: 0xf297c000         set: 3 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 272         dbwrid: 0 obj: 54208 objn: 54202 tsn: 0 afn: 1         hash: [f2fc47f8,1181f3038] lru: [f2fc6b88,f2fc6968]         obj-flags: object_ckpt_list         ckptq: [1182ecf38,1182ecf38] fileq: [1182ecf58,1182ecf58] objq: [108712a28,108712a28]         use: [1182dc790,1182dc790] wait: [NULL]         st: XCURRENT md: SHR tch: 12         flags: buffer_dirty gotten_in_current_mode block_written_once                 redo_since_read         LRBA: [0xc7.73b.0] HSCN: [0x0.1cbe52] HSUB: [1]         Using State Objects           ----------------------------------------           SO: 0x1182dc750, type: 24, owner: 0x11b452348, flag: INIT/-/-/0x00           (buffer) (CR) PR: 0x11b305810 FLG: 0x108000           class bit: (nil)           kcbbfbp: [BH: 0xf2fc69f8, LINK: 0x1182dc790]           where: kdswh05: kdsgrp, why: 0         buffer tsn: 0 rdba: 0x00410652 (1/67154)         scn: 0x0000.001cbe52 seq: 0x01 flg: 0x02 tail: 0xbe520601         frmt: 0x02 chkval: 0x0000 type: 0x06=trans data tab 0, row 0, @0x1f9a tl: 6 fb: --H-FL-- lb: 0x0  cc: 1 col  0: [ 2]  c1 02 tab 0, row 1, @0x1f94 tl: 6 fb: --H-FL-- lb: 0x2  cc: 1 col  0: [ 2]  c1 15 end_of_block_dump         (buffer) (CR) PR: 0x11b305810 FLG: 0x108000 st: XCURRENT md: SHR tch: 12 ? buffer header?status= XCURRENT mode=KCBMSHARE KCBMSHR     current share ?????  x$kcbbf ????? cache buffer handle SQL> select distinct KCBBPBH from  x$kcbbf ; KCBBPBH ---------------- 00 00000000F2FC69F8            ==>0xf2fc69f8 SQL> select * from x$kcbbf where kcbbpbh='00000000F2FC69F8'; ADDR                   INDX    INST_ID KCBBFSO_TYP KCBBFSO_FLG KCBBFSO_OWN ---------------- ---------- ---------- ----------- ----------- ----------------   KCBBFFLG    KCBBFCR    KCBBFCM KCBBFMBR         KCBBPBH ---------- ---------- ---------- ---------------- ---------------- KCBBPBF          X0KCBBPBH        X0KCBBPBF        X1KCBBPBH ---------------- ---------------- ---------------- ---------------- X1KCBBPBF        KCBBFBH            KCBBFWHR   KCBBFWHY ---------------- ---------------- ---------- ---------- 00000001182DC750        748          1          24           1 000000011B452348    1081344          1          0 00               00000000F2FC69F8 00000001182DC750 00               00000001182DC750 00 00000001182DC7F8 00                      583          0 SQL> desc x$kcbbf;  Name                                      Null?    Type  ----------------------------------------- -------- ----------------------------  ADDR                                               RAW(8)  INDX                                               NUMBER  INST_ID                                            NUMBER  KCBBFSO_TYP                                        NUMBER  KCBBFSO_FLG                                        NUMBER  KCBBFSO_OWN                                        RAW(8)  KCBBFFLG                                           NUMBER  KCBBFCR                                            NUMBER  KCBBFCM                                            NUMBER  KCBBFMBR                                           RAW(8)  KCBBPBH                                            RAW(8)  KCBBPBF                                            RAW(8)  X0KCBBPBH                                          RAW(8)  X0KCBBPBF                                          RAW(8)  X1KCBBPBH                                          RAW(8)  X1KCBBPBF                                          RAW(8)  KCBBFBH                                            RAW(8)  KCBBFWHR                                           NUMBER  KCBBFWHY                                           NUMBER gdb ?? ?process??????kcbrls release buffer? ???cache buffer handle??? SQL> select distinct KCBBPBH from  x$kcbbf ; KCBBPBH ---------------- 00

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• Problem with waitable timers in Windows (timeSetEvent and CreateTimerQueueTimer)

  - by MusiGenesis

  I need high-resolution (more accurate than 1 millisecond) timing in my application. The waitable timers in Windows are (or can be made) accurate to the millisecond, but if I need a precise periodicity of, say, 35.7142857141 milliseconds, even a waitable timer with a 36 ms period will drift out of sync quickly. My "solution" to this problem (in ironic quotes because it's not working quite right) is to use a series of one-shot timers where I use the expiration of each timer to call the next timer. Normally a process like this would be subject to cumulative error over time, but in each timer callback I check the current time (with System.Diagnostics.Stopwatch) and use this to calculate what the period of the next timer needs to be (so if a timer happens to expire a little late, the next timer will automagically have a shorter period to compensate). This works as expected, except that after maybe 10-15 seconds the timer system seems to get bogged down, and a few timer callbacks here and there arrive anywhere from 25 to 100 milliseconds late. After a couple of seconds the problem goes away and everything runs smoothly again for 10-15 seconds, and then the stuttering again. Since I'm using Stopwatch to set each timer period, I'm also using it to monitor the arrival times of each timer callback. During the smooth-running periods, most (maybe 95%) of the intervals are either 35 or 36 milliseconds, and no intervals are ever more than 5 milliseconds away from the expected 35.7142857143. During the "glitchy" stretches, the distribution of intervals is very nearly identical, except that a very small number are unusually large (a couple more than 60 ms and one or two longer than 100 ms during maybe a 3-second stretch). This stuttering is very noticeable, and it's what I'm trying to fix, if possible. For the high-resolution timer, I was using the extremely antique timeSetEvent() multimedia timer from winmm.dll. In pursuit of this problem, I switched to using CreateTimerQueueTimer (along with timeBeginPeriod to set the high-resolution), but I'm seeing the same problem with both timer mechanisms. I've tried experimenting with the various flags for CreateTimerQueueTimer which determine which thread the timer runs on, but the stuttering appears no matter what. Is this just a fundamental problem with using timers in this way (i.e. using each one-shot timer to call the next)? If so, do I have any alternatives? One thing I was considering was to determine how many consecutive 1-millisecond-accuracy ticks would keep my within some arbitrary precision limit before I need to reset the timer. So, for example, if I wanted a 35.71428 period, I could let a 36 ms timer elapse 15 times before it was off by 5 milliseconds, then kill it and start a new one.

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• iPad application crash in Apple review - cannot replicate in simulator, have crash log

  - by Mike

  I am clearly missing something obvious here and would really appreciate some input. I have tried repeatedly to submit an application to Apple (iPad in this case) that is crashing on their end when testing but I cannot replicated the situation on my end (obviously I only have the damned simulator to work with at this point). The crash log is as follows: Date/Time: 2010-04-01 05:39:47.226 -0700 OS Version: iPhone OS 3.2 (7B367) Report Version: 104 Exception Type: EXC_CRASH (SIGABRT) Exception Codes: 0x00000000, 0x00000000 Crashed Thread: 0 Thread 0 Crashed: 0 libSystem.B.dylib 0x000790a0 __kill + 8 1 libSystem.B.dylib 0x00079090 kill + 4 2 libSystem.B.dylib 0x00079082 raise + 10 3 libSystem.B.dylib 0x0008d20a abort + 50 4 libstdc++.6.dylib 0x00044a1c __gnu_cxx::__verbose_terminate_handler() + 376 5 libobjc.A.dylib 0x000057c4 _objc_terminate + 104 6 libstdc++.6.dylib 0x00042dee __cxxabiv1::__terminate(void (*)()) + 46 7 libstdc++.6.dylib 0x00042e42 std::terminate() + 10 8 libstdc++.6.dylib 0x00042f12 __cxa_throw + 78 9 libobjc.A.dylib 0x000046a4 objc_exception_throw + 64 10 CoreFoundation 0x00090c6e +[NSException raise:format:arguments:] + 74 11 CoreFoundation 0x00090d38 +[NSException raise:format:] + 28 12 Foundation 0x00002600 -[NSCFDictionary setObject:forKey:] + 184 13 iPadMosaic 0x00003282 -[iPadMosaicViewController getAlbumThumbs] (iPadMosaicViewController.m:468) 14 Foundation 0x000728fe __NSFireDelayedPerform + 314 15 CoreFoundation 0x00022d1c CFRunLoopRunSpecific + 2092 16 CoreFoundation 0x000224da CFRunLoopRunInMode + 42 17 GraphicsServices 0x000030d4 GSEventRunModal + 108 18 GraphicsServices 0x00003180 GSEventRun + 56 19 UIKit 0x000034c2 -[UIApplication _run] + 374 20 UIKit 0x000019ec UIApplicationMain + 636 21 iPadMosaic 0x00002234 main (main.m:14) 22 iPadMosaic 0x00002204 start + 32 My understanding here is that I am botching the Dictionary add somehow. The relevant lines of code are: for (NSDictionary *album in self.albumList) { // Get image for each album cover UIImage *albumCover; // Loop through photos to get URL of cover based on photo ID match NSString *coverURL = @""; for (NSDictionary *photo in self.photoList) { if ([[photo objectForKey:@"pid"] isEqualToString:[album objectForKey:@"cover_pid"]]) { coverURL = [photo objectForKey:@"src"]; } } NSURL *albumCoverURL = [NSURL URLWithString:coverURL]; NSData *albumCoverData = [NSData dataWithContentsOfURL:albumCoverURL]; albumCover = [UIImage imageWithData:albumCoverData]; if (albumCover == nil || albumCover == NULL) { //NSLog(@"No album cover for some reason"); albumCover = [UIImage imageNamed:@"noImage.png"]; } [[self.albumList objectAtIndex:albumCurrent] setObject:albumCover forKey:@"coverThumb"]; } This is part of a loop that runs over the existing dictionaries stored in an array. If retrieving the album cover fails for some reason the object is filled with a default image and then added. The last line of the code is what's showing up in the crash log. It runs fine in the simulator but crashes 100% in testing on device apparently. Can anyone tell me what I am missing here?

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• WPF Animation FPS vs. CPU usage - Am I expecting too much?

  - by Cory Charlton

  Working on a screen saver for my wife, http://cchearts.codeplex.com/, and while I've been able to improve FPS on lower end machines (switch from Path to StreamGeometry, use DrawingVisual instead of UserControl, etc) the CPU usage still seems very high. Here's some numbers I ran from a few 5 minute sampling periods: ~60FPS 35% average CPU on Core 2 Duo T7500 @ 2.2GHz, 3GB ram, NVIDIA Quadro NVS 140M (128MB), Vista [My dev laptop] ~40FPS 50% average CPU on Pentium D @ 3.4GHz, 1.5GB ram, Standard VGA Graphics Adapter (unknown), 2003 Server [A crappy desktop] I can understand the lower frame rate and higher CPU usage on the crappy desktop but it still seems pretty high and 35% on my dev laptop seems high as well. I'd really like to analyze the application to get more details but I'm having issues there as well so I'm wondering if I'm doing something wrong (never profiled WPF before). WPF Performance Suite: Process Launch Error Unable to attach to process: CCHearts.exe Do you want to kill it? This error message occurs when I click cancel after attempting launch. If I don't click cancel it sits there idle, I guess waiting to attach. Performance Explorer: Could not launch C:\Projects2\CC.Hearts\CC.Hearts\bin\Debug (USEVISUAL)\CCHearts.exe. Previous attempt to profile the application finished unsuccessfully. Please restart the application. Output Window from Performance: Profiling started. Profiling process ID 5360 (CCHearts). Process ID 5360 has exited. Data written to C:\Projects2\CC.Hearts\CCHearts100608.vsp. Profiling finished. PRF0025: No data was collected. Profiling complete. So I'm stuck wanting to improve performance but have no concrete way to determine where the bottleneck is. Have been relatively successful throwing darts at this point but I'm beyond that now :) PS: Screensaver is hosted at CodePlex if you want to look at the source and missed the link above. Edit: My RenderOptions darts... // NOTE: Grasping at straws here ;-) RenderOptions.SetBitmapScalingMode(newHeart, BitmapScalingMode.LowQuality); RenderOptions.SetCachingHint(newHeart, CachingHint.Cache); RenderOptions.SetEdgeMode(newHeart, EdgeMode.Aliased); I threw those a little while back and didn't see much difference (not sure if the bitmap scaling even comes into play). Really wish I could get profiling working to know where I should try to optimize. For now I assume there is some overhead in creating a new HeartVisual and the DrawingVisual contained inside. Maybe if I reset and reused the hearts (tossed them in a queue once they completed or something) I'd see an improvement. Shrug Throwing darts while blindfolder is always fun.

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• Properly clean up excel interop objects revisited: Wrapper objects

  - by chiccodoro

  Hi all, Excel 2007 Hangs When Closing via .NET How to properly clean up Excel interop objects in C# How to properly clean up interop objects in C# All of these struggle with the problem that C# does not release the Excel COM objects properly after using them. There are mainly two directions of working around this issue: Kill the Excel process when Excel is not used anymore. Take care to assign each COM object used explicitly to a variable and to Marshal.ReleaseComObject all of these. Some have stated that 2 is too tedious and there is always some uncertainty whether you forget to stick to this rule at some places in the code. Still 1 seems dirty and dangerous to me, also I could imagine that in an environment with restricted access killing processes is not allowed. So I've been thinking about solving 2 by creating another proxy object model which mimics the Excel object model (for me, it would suffice to implement the objects I actually need). The principle would look as follows: Each Excel Interop class has its proxy which wraps an object of that class. The proxy releases the COM object in its destructor. The proxy mimics the interface of the Interop class (maybe by inheriting it). Any methods that usually return another COM object return a proxy instead. The other methods simply delegate the implementation to the inner COM object. This is a rough sketch of the code: public class Application : Microsoft.Office.Interop.Excel.Application { private Microsoft.Office.Interop.Excel.Application innerApplication = new Microsoft.Office.Interop.Excel.Application innerApplication(); ~Application() { Marshal.ReleaseCOMObject(innerApplication); } public Workbooks Workbooks { get { return new Workbooks(innerApplication.Workbooks); } } } public class Workbooks { private Microsoft.Office.Interop.Excel.Workbooks innerWorkbooks; Workbooks(Microsoft.Office.Interop.Excel.Workbooks innerWorkbooks) { this.innerWorkbooks = innerWorkbooks; } ~Workbooks() { Marshal.ReleaseCOMObject(innerWorkbooks); } } My questions to you are in particular: Who finds this a bad idea and why? Who finds this a gread idea? If so, why hasn't anybody implemented/published such a model yet? Just due to the effort, or am I missing a killing problem with that idea? Is it impossible/bad/dangerous to do the ReleaseCOMObject in the destructor? (I've only seen proposals to put it in a Dispose() rather than in a destructor - why?) If the approach makes sense, any suggestions to improve it?

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• XML Socket and Regular Socket in Flash/Flex does not send message immediately.

  - by kramer

  I am trying to build a basic RIA where my Flex application client opens an XML socket, sends the xml message "people_list" to server, and prints out the response. I have ruby at the server side and I have successfully set up the security policy stuff. The ruby xml server, successfully accepts the connections from Flex, successfully detects when they are closed and can also send messages to client. But; there is a problem... It cannot receive messages from flex client. The messages sent from flex client are queued and sent as one package when the socket is closed. Therefore, the whole wait-for-request-then-reply thing is not working... This is also -kinda- mentioned in the XMLSocket.send() document, where it is stated that the messages are sent async so; they may be delivered at any time in future. But; I need them to be synced, flushed or whatever. This is the server side code: require 'socket' require 'observer' class Network_Reader_Ops include Observable @@reader_listener_socket = UDPSocket.new @@reader_broadcast_socket = UDPSocket.new @@thread_id def initialize @@reader_broadcast_socket.setsockopt(Socket::SOL_SOCKET, Socket::SO_BROADCAST, 1) @@reader_broadcast_socket.setsockopt(Socket::SOL_SOCKET, Socket::SO_REUSEADDR, 1) @@reader_listener_socket.setsockopt(Socket::SOL_SOCKET, Socket::SO_REUSEADDR, 1) @@reader_broadcast_socket.bind('', 50050) @@reader_listener_socket.bind('', 50051) @@thread_id = Thread.start do loop do begin text, sender = @@reader_listener_socket.recvfrom_nonblock 1024 print("Knock response recived: ", text) notify_observers text rescue Errno::EAGAIN retry rescue Errno::EWOULDBLOCK retry end end end end def query @@reader_broadcast_socket.send("KNOCK KNOCK", 0, "255.255.255.255", 50050) end def stop Thread.kill @@thread_id end end class XMLSocket_Connection attr_accessor :connection_id def update (data) connection_id.write(data+"\0") end end begin # Set EOL for Flash $/ = '\x00' xml_socket = TCPServer.open('', '4444') security_policy_socket = TCPServer.open('', '843') xml_socket.setsockopt(Socket::SOL_SOCKET, Socket::SO_REUSEADDR, 1) security_policy_socket.setsockopt(Socket::SOL_SOCKET, Socket::SO_REUSEADDR, 1) a = Thread.start do network_ops = nil loop { accepted_connection = xml_socket.accept print(accepted_connection.peeraddr, " is accepted\n") while accepted_connection.gets incoming = $_.dump print("Received: ", incoming) if incoming == "<request>readers on network</request>" then network_ops = Network_Reader_Ops.new this_con = XMLSocket_Connection.new this_con.connection_id = accepted_connection network_ops.add_observer this_con network_ops.query end end if not network_ops.nil? then network_ops.delete_observer this_con network_ops.stop network_ops = nil end print(accepted_connection, " is gone\n") accepted_connection.close } end b = Thread.start do loop { accepted_connection = security_policy_socket.accept Thread.start do current_connection = accepted_connection while current_connection.gets if $_ =~ /.*policy\-file.*/i then current_connection.write("<cross-domain-policy><allow-access-from domain="*" to-ports="*" /></cross-domain-policy>\0") end end current_connection.close end } end a.join b.join rescue puts "FAILED" retry end And this is the flex/flash client side code: UPDATE: I have also tried using regular socket and calling flush() method but; the result was same. private var socket:XMLSocket = new XMLSocket(); protected function stopXMLSocket():void { socket.close(); } protected function startXMLSocket():void { socket.addEventListener(DataEvent.DATA, dataHandler); socket.connect(xmlSocketServer_address, xmlSocketServer_port); socket.send("<request>readers on network</request>"); } protected function dataHandler(event:DataEvent):void { mx.controls.Alert.show(event.data); } How do I achieve the described behaviour?

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• Uploading a file using post() method of QNetworkAccessManager

  - by user304361

  I'm having some trouble with a Qt application; specifically with the QNetworkAccessManager class. I'm attempting to perform a simple HTTP upload of a binary file using the post() method of the QNetworkAccessManager. The documentation states that I can give a pointer to a QIODevice to post(), and that the class will transmit the data found in the QIODevice. This suggests to me that I ought to be able to give post() a pointer to a QFile. For example: QFile compressedFile("temp"); compressedFile.open(QIODevice::ReadOnly); netManager.post(QNetworkRequest(QUrl("http://mywebsite.com/upload") ), &compressedFile); What seems to happen on the Windows system where I'm developing this is that my Qt application pushes the data from the QFile, but then doesn't complete the request; it seems to be sitting there waiting for more data to show up from the file. The post request isn't "closed" until I manually kill the application, at which point the whole file shows up at my server end. From some debugging and research, I think this is happening because the read() operation of QFile doesn't return -1 when you reach the end of the file. I think that QNetworkAccessManager is trying to read from the QIODevice until it gets a -1 from read(), at which point it assumes there is no more data and closes the request. If it keeps getting a return code of zero from read(), QNetworkAccessManager assumes that there might be more data coming, and so it keeps waiting for that hypothetical data. I've confirmed with some test code that the read() operation of QFile just returns zero after you've read to the end of the file. This seems to be incompatible with the way that the post() method of QNetworkAccessManager expects a QIODevice to behave. My questions are: Is this some sort of limitation with the way that QFile works under Windows? Is there some other way I should be using either QFile or QNetworkAccessManager to push a file via post()? Is this not going to work at all, and will I have to find some other way to upload my file? Any suggestions or hints would be appreciated. Thanks, Don

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• timeIntervalSinceDate Accuracy

  - by mmccomb

  I've been working on a game with an engine that updates 20 times per seconds. I've got to point now where I want to start getting some performance figures and tweak the rendering and logic updates. In order to do so I started to add some timing code to my game loop, implemented as follows... NSDate* startTime = [NSDate date]; // Game update logic here.... // Also timing of smaller internal events NSDate* endTime = [NSDate date]; [endTime timeIntervalSinceDate:startTime]; I noticed however that when I timed blocks within the outer timing logic that the time they took to execute did not sum up to match the overall time taken. So I wrote a small unit test to demonstrate the problem in which I time the overall time taken to complete the test and then 10 smaller events, here it is... - (void)testThatSumOfTimingsMatchesOverallTiming { NSDate* startOfOverallTime = [NSDate date]; // Variable to hold summation of smaller timing events in the upcoming loop... float sumOfIndividualTimes = 0.0; NSTimeInterval times[10] = {0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0}; for (int i = 0; i < 10; i++) { NSDate* startOfIndividualTime = [NSDate date]; // Kill some time... sleep(1); NSDate* endOfIndividualTime = [NSDate date]; times[i] = [endOfIndividualTime timeIntervalSinceDate:startOfIndividualTime]; sumOfIndividualTimes += times[i]; } NSDate* endOfOverallTime = [NSDate date]; NSTimeInterval overallTimeTaken = [endOfOverallTime timeIntervalSinceDate:startOfOverallTime]; NSLog(@"Sum of individual times: %fms", sumOfIndividualTimes); NSLog(@"Overall time: %fms", overallTimeTaken); STAssertFalse(TRUE, @""); } And here's the output... Sum of individual times: 10.001377ms Overall time: 10.016834ms Which illustrates my problem quite clearly. The overall time was 0.000012ms but the smaller events took only 0.000001ms. So what happened to the other 0.000011ms? Is there anything that looks particularly wrong with my code? Or is there an alternative timing mechanism I should use?

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• Taking screenshot with Win32 API (C# pInvoke) not working in IIS

  - by Dillen Meijboom

  I want to take a screenshot of an external website. Currently my workflow is to start a Firefox instance with the specified URL and take a screenshot using PrintWindow in the Win32 API When I run this application in IISExpress it works fine but when I run the same application in IIS on a windows VPS it is not working (screenshot is blank). I don't know what I'm doing wrong? My code: using Newtonsoft.Json; using System; using System.Collections.Generic; using System.Diagnostics; using System.Drawing; using System.Drawing.Imaging; using System.Linq; using System.Runtime.InteropServices; using System.Security; using System.Threading; using System.Web; namespace WebTools.Web { public class RemoteScreenshot { public static Bitmap TakeScreenshot(Process process) { // may need a process Refresh before return TakeScreenshot(process.MainWindowHandle); } public static Bitmap TakeScreenshot(IntPtr handle) { RECT rc = new RECT(); GetWindowRect(handle, ref rc); Bitmap bitmap = new Bitmap(rc.right - rc.left, rc.bottom - rc.top); using (Graphics graphics = Graphics.FromImage(bitmap)) { PrintWindow(handle, graphics.GetHdc(), 0); } return bitmap; } [DllImport("user32.dll")] private static extern bool GetWindowRect(IntPtr hWnd, ref RECT rect); [DllImport("user32.dll")] private static extern bool PrintWindow(IntPtr hWnd, IntPtr hDC, int flags); [StructLayout(LayoutKind.Sequential)] private struct RECT { public int left; public int top; public int right; public int bottom; } public static void Save(string url, string file, int timeout = 0) { Process.Start(new ProcessStartInfo("C:\\Program Files (x86)\\Mozilla Firefox\\firefox.exe", url) { CreateNoWindow = false, WindowStyle = ProcessWindowStyle.Maximized }); Thread.Sleep(timeout); var bitmap = TakeScreenshot(Process.GetProcessesByName("firefox").First()); bitmap.Save(file, ImageFormat.Png); bitmap.Dispose(); Process.GetProcessesByName("firefox").First().Kill(); } } } EDIT: Running Firefox works fine because the AppPool is under another account that has the rights to execute firefox.

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• Problem in running boost eample blocking_udp_echo_client on MacOSX

  - by n179911

  I am trying to run blocking_udp_echo_client on MacOS X http://www.boost.org/doc/libs/1_35_0/doc/html/boost_asio/example/echo/blocking_udp_echo_client.cpp I run it with argument 'localhost 9000' But the program crashes and this is the line in the source which crashes: `udp::socket s(io_service, udp::endpoint(udp::v4(), 0));' this is the stack trace: #0 0x918c3e42 in __kill #1 0x918c3e34 in kill$UNIX2003 #2 0x9193623a in raise #3 0x91942679 in abort #4 0x940d96f9 in __gnu_debug::_Error_formatter::_M_error #5 0x0000e76e in __gnu_debug::_Safe_iterator::op_base* , __gnu_debug_def::list::op_base*, std::allocator::op_base* ::_Safe_iterator at safe_iterator.h:124 #6 0x00014729 in boost::asio::detail::hash_map::op_base*::bucket_type::bucket_type at hash_map.hpp:277 #7 0x00019e97 in std::_Construct::op_base*::bucket_type, boost::asio::detail::hash_map::op_base*::bucket_type at stl_construct.h:81 #8 0x0001a457 in std::__uninitialized_fill_n_aux::op_base*::bucket_type*, __gnu_norm::vector::op_base*::bucket_type, std::allocator::op_base*::bucket_type , unsigned long, boost::asio::detail::hash_map::op_base*::bucket_type at stl_uninitialized.h:194 #9 0x0001a4e1 in std::uninitialized_fill_n::op_base*::bucket_type*, __gnu_norm::vector::op_base*::bucket_type, std::allocator::op_base*::bucket_type , unsigned long, boost::asio::detail::hash_map::op_base*::bucket_type at stl_uninitialized.h:218 #10 0x0001a509 in std::__uninitialized_fill_n_a::op_base*::bucket_type*, __gnu_norm::vector::op_base*::bucket_type, std::allocator::op_base*::bucket_type , unsigned long, boost::asio::detail::hash_map::op_base*::bucket_type, boost::asio::detail::hash_map::op_base*::bucket_type at stl_uninitialized.h:310 #11 0x0001aa34 in __gnu_norm::vector::op_base*::bucket_type, std::allocator::op_base*::bucket_type ::_M_fill_insert at vector.tcc:365 #12 0x0001acda in __gnu_norm::vector::op_base*::bucket_type, std::allocator::op_base*::bucket_type ::insert at stl_vector.h:658 #13 0x0001ad81 in __gnu_norm::vector::op_base*::bucket_type, std::allocator::op_base*::bucket_type ::resize at stl_vector.h:427 #14 0x0001ae3a in __gnu_debug_def::vector::op_base*::bucket_type, std::allocator::op_base*::bucket_type ::resize at vector:169 #15 0x0001b7be in boost::asio::detail::hash_map::op_base*::rehash at hash_map.hpp:221 #16 0x0001bbeb in boost::asio::detail::hash_map::op_base*::hash_map at hash_map.hpp:67 #17 0x0001bc74 in boost::asio::detail::reactor_op_queue::reactor_op_queue at reactor_op_queue.hpp:42 #18 0x0001bd24 in boost::asio::detail::kqueue_reactor::kqueue_reactor at kqueue_reactor.hpp:86 #19 0x0001c000 in boost::asio::detail::service_registry::use_service at service_registry.hpp:109 #20 0x0001c14d in boost::asio::use_service at io_service.ipp:195 #21 0x0001c26d in boost::asio::detail::reactive_socket_service ::reactive_socket_service at reactive_socket_service.hpp:111 #22 0x0001c344 in boost::asio::detail::service_registry::use_service at service_registry.hpp:109 #23 0x0001c491 in boost::asio::use_service at io_service.ipp:195 #24 0x0001c4d5 in boost::asio::datagram_socket_service::datagram_socket_service at datagram_socket_service.hpp:95 #25 0x0001c59e in boost::asio::detail::service_registry::use_service at service_registry.hpp:109 #26 0x0001c6eb in boost::asio::use_service at io_service.ipp:195 #27 0x0001c711 in boost::asio::basic_io_object ::basic_io_object at basic_io_object.hpp:72 #28 0x0001c783 in boost::asio::basic_socket ::basic_socket at basic_socket.hpp:108 #29 0x0001c865 in boost::asio::basic_datagram_socket ::basic_datagram_socket at basic_datagram_socket.hpp:107 #30 0x000027bc in main at main.cpp:32 This is the gdb output: (gdb) continue /Developer/SDKs/MacOSX10.5.sdk/usr/include/c++/4.0.0/debug/safe_iterator.h:127: error: attempt to copy-construct an iterator from a singular iterator. Objects involved in the operation: iterator "this" @ 0x0x100420 { type = N11__gnu_debug14_Safe_iteratorIN10__gnu_norm14_List_iteratorISt4pairIiPN5boost4asio6detail16reactor_op_queueIiE7op_baseEEEEN15__gnu_debug_def4listISB_SaISB_EEEEE (mutable iterator); state = singular; } iterator "other" @ 0x0xbfffe8a4 { type = N11__gnu_debug14_Safe_iteratorIN10__gnu_norm14_List_iteratorISt4pairIiPN5boost4asio6detail16reactor_op_queueIiE7op_baseEEEEN15__gnu_debug_def4listISB_SaISB_EEEEE (mutable iterator); state = singular; } Program received signal: “SIGABRT”. (gdb) continue Program received signal: “?”. Does someone has any idea why this example does not work on mac osx? Thank you.

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• PulpCore music playback - loop sound and animate volume

  - by Peter Perhác

  I have been experimenting with PulpCore, trying to create my own tower defence game (not-playable yet), and I am enjoying it very much I ran into a problem that I can't quite figure out. I extended PulpCore with the JOrbis thing to allow OGG files to be played. Works fine. However, pulpCore seems to have a problem with looping the sound WHILE animating the volume level. I tried this with wav file too, to make sure it isn't jOrbis that breaks it. The code is like this: Sound bgMusic = Sound.load("music/music.ogg"); Playback musicPlayback; ... musicVolume = new Fixed(0.75); musicPlayback = bgMusic.loop(musicVolume); //TODO figure out why it's NOT looping when volume is animated // musicVolume.animate(0, musicVolume.get(), FADE_IN_TIME); This code, for as long as the last line is commented out, plays the music.ogg again and again in an endless loop (which I can stop by calling stop on the Playback object returned from loop(). However, I would like the music to fade in smoothly, so following the advice of the PulpCore API docs, I added the last line which will create the fade-in but the music will only play once and then stop. I wonder why is that? Here is a bit of the documentation: Playback pulpcore.sound.Sound.loop(Fixed level) Loops this sound clip with the specified volume level (0.0 to 1.0). The level may have a property animation attached. Parameters: level Returns: a Playback object for this unique sound playback (one Sound can have many simultaneous Playback objects) or null if the sound could not be played. So what could be the problem? I repeat, with the last line, the sound fades in but doesn't loop, without it it loops but starts with the specified 0.75 volume level. Why can't I animate the volume of the looped music playback? What am I doing wrong? Anyone has any experience with pulpCore and has come across this problem? Anyone could please download PulpCore and try to loop music which fades-in (out)? note: I need to keep a reference to the Playback object returned so I can kill music later.

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• Learning to create beautiful /next-generation GUI

  - by ShaChris23

  I really want to create a stunning-looking GUI desktop application that looks like, for example: Mac OS X interface Picasa desktop client on windows IPhone apps Office 2007 I've mostly been programming GUI using Qt/Swing/WinForm and I'm tired of creating so plain looking GUI, lol. So I was thinking about diving into stuff like: jQuery WPF/C# iPhone SDK Silverlight Adobe Air/Flex Just to get some ideas on how to create really cool looking UI. Does that sound like a good list? Any developers here that could share what platform they use to create very cool looking desktop app? On a sidenote, I really wonder what developers at Apple / Microsoft use to develop their own cool-looking software. EDIT A lot of responses talk about the importance of usability over "cool-looking".. I totally agree that usability and simplicity are the most important aspects of user interface design. I've been doing GUI development for a while now ( 3 years), so that I understand. But using cool-looking UI also improves user experience + it could make big difference on whether or not your software sells. I mean, otherwise why would Microsoft/Apple try to make their OS UI look "cooler" everytime there's a new version? Why would websites like pragprog.com, or versionsapp.com. make their websites look like that? Basically you kill 2 birds with one stone: stunnning-looking UI + super usability (because it looks simple and intuitive). That is what I'm striving for. And as far as I know, I cannot achieve that using Qt/Winform. Most of the books I have read just show you how to make average-looking (read: 1990's) UI. I want to learn how to create cool-looking UI. And the only place I see cool-looking UIs these days are the technology I list above. I'm not enamored with any technology; but I just want to know how things are done in other technology to see if I could apply them to the technology I'm using, or see if I could use those technology in my line of work. An example: if I were to pick between this UI and this UI, I probably would pick the latter, if just based on looks alone. Functionally, they are just the same UI; they both allow you to keep track of your time. They both contain buttons and textboxes, etc. But the fact that they look different, also differentiate them in terms of attractiveness. So in all, I think the "ice on the cake" is very important. I would say it's the thing you strive for after you are certain you have a totally intuitive, usable UI.

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• How to break a Hibernate session?

  - by Péter Török

  In the Hibernate reference, it is stated several times that All exceptions thrown by Hibernate are fatal. This means you have to roll back the database transaction and close the current Session. You aren’t allowed to continue working with a Session that threw an exception. One of our legacy apps uses a single session to update/insert many records from files into a DB table. Each recourd update/insert is done in a separate transaction, which is then duly committed (or rolled back in case an error occurred). Then for the next record a new transaction is opened etc. But the same session is used throughout the whole process, even if a HibernateException was caught in the middle. We are using Oracle 9i btw with Hibernate 3.24.sp1 on JBoss 4.2. Reading the above in the book, I realized that this design may fail. So I refactored the app to use a separate session for each record update. In a unit test with a mock session factory, I could prove that it is now requesting a new session for each record update. So far, so good. However, we found no way to reproduce the session failure while testing the whole app (would this be a stress test btw, or ...?). We thought of shutting down the listener of the DB but we realized that the app is keeping a bunch of connections open to the DB, and the listener would not affect those connections. (This is a web app, activated once every night by a scheduler, but it can also be activated via the browser.) Then we tried to kill some of those connections in the DB while the app was processing updates - this resulted in some failed updates, but then the app happily continued. Apparently Hibernate is clever enough to reopen broken connections under the hood without breaking the whole session. So this might not be a critical issue, as our app seems to be robust enough even in its original form. However, the issue keeps bugging me. I would like to know: Under what circumstances does the Hibernate session really become unusable after a HibernateException was thrown? How to reproduce this in a test? (What's the proper term for such a test?)

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• .NET 2.0 Process Elevation for App Installation

  - by Brian Gillespie

  We have an application written in both C++ and .NET that installs for all users in the Program Files folder. This application downloads new versions of itself (as MSI installers) and spawns the new installer process to replace itself. The install process as it exists today: Copy an install manager app (C#, .NET 2.0) to the temp directory. Call this 'Manager' Manager is executed with elevated privs per this article. The original application exits. Manager spawns the MSI installer (with elevated privs, since the copy is elevated) Manager spawns the new version of the app. The bug: The newly installed app is running in an elevated state. This causes problems I won't enumerate here. Ideally, the launch of the newly installed app would be run with the permissions of the original user. I can't figure out how to demote the app back to being the standard user after elevation. An inelegant hack: (yeah, yeah, this whole process is inelegant anyway) Copy the install manager to the temp directory Run the install manager with standard user privs. Lets call this instance 'LowlyManager'. Original application exits. LowlyManager spawns the app again, this time with elevated privs. Let's name this instance 'UpperManagement' UpperManagement spawns the installer UpperManagement exits gracefully, returning the exit code of the installer. LowlyManager interprets the error code from UpperManagement, and spawns the newly installed application. This time as the original invoker. Is there a better way to do this? (I've left out a bunch of other details before and after these steps that make the process smoother for the user, but this should be enough to understand the core of the problem I'm trying to solve.) Other requirements: We can't install as a per-user app The user shouldn't be presented with an authentication dialog box if UAC would have simply asked "are you sure you want to allow this?". I think this might kill a solution using WindowsImpersonationContext, but I'm not sure. The system needs to work on XP, Vista, and Windows 7 (even if there is a separate process for XP).

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