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  • Unable to cast transparent proxy to type &lt;type&gt;

    - by Rick Strahl
    This is not the first time I've run into this wonderful error while creating new AppDomains in .NET and then trying to load types and access them across App Domains. In almost all cases the problem I've run into with this error the problem comes from the two AppDomains involved loading different copies of the same type. Unless the types match exactly and come exactly from the same assembly the typecast will fail. The most common scenario is that the types are loaded from different assemblies - as unlikely as that sounds. An Example of Failure To give some context, I'm working on some old code in Html Help Builder that creates a new AppDomain in order to parse assembly information for documentation purposes. I create a new AppDomain in order to load up an assembly process it and then immediately unload it along with the AppDomain. The AppDomain allows for unloading that otherwise wouldn't be possible as well as isolating my code from the assembly that's being loaded. The process to accomplish this is fairly established and I use it for lots of applications that use add-in like functionality - basically anywhere where code needs to be isolated and have the ability to be unloaded. My pattern for this is: Create a new AppDomain Load a Factory Class into the AppDomain Use the Factory Class to load additional types from the remote domain Here's the relevant code from my TypeParserFactory that creates a domain and then loads a specific type - TypeParser - that is accessed cross-AppDomain in the parent domain:public class TypeParserFactory : System.MarshalByRefObject,IDisposable { …/// <summary> /// TypeParser Factory method that loads the TypeParser /// object into a new AppDomain so it can be unloaded. /// Creates AppDomain and creates type. /// </summary> /// <returns></returns> public TypeParser CreateTypeParser() { if (!CreateAppDomain(null)) return null; /// Create the instance inside of the new AppDomain /// Note: remote domain uses local EXE's AppBasePath!!! TypeParser parser = null; try { Assembly assembly = Assembly.GetExecutingAssembly(); string assemblyPath = Assembly.GetExecutingAssembly().Location; parser = (TypeParser) this.LocalAppDomain.CreateInstanceFrom(assemblyPath, typeof(TypeParser).FullName).Unwrap(); } catch (Exception ex) { this.ErrorMessage = ex.GetBaseException().Message; return null; } return parser; } private bool CreateAppDomain(string lcAppDomain) { if (lcAppDomain == null) lcAppDomain = "wwReflection" + Guid.NewGuid().ToString().GetHashCode().ToString("x"); AppDomainSetup setup = new AppDomainSetup(); // *** Point at current directory setup.ApplicationBase = AppDomain.CurrentDomain.BaseDirectory; //setup.PrivateBinPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "bin"); this.LocalAppDomain = AppDomain.CreateDomain(lcAppDomain,null,setup); // Need a custom resolver so we can load assembly from non current path AppDomain.CurrentDomain.AssemblyResolve += new ResolveEventHandler(CurrentDomain_AssemblyResolve); return true; } …} Note that the classes must be either [Serializable] (by value) or inherit from MarshalByRefObject in order to be accessible remotely. Here I need to call methods on the remote object so all classes are MarshalByRefObject. The specific problem code is the loading up a new type which points at an assembly that visible both in the current domain and the remote domain and then instantiates a type from it. This is the code in question:Assembly assembly = Assembly.GetExecutingAssembly(); string assemblyPath = Assembly.GetExecutingAssembly().Location; parser = (TypeParser) this.LocalAppDomain.CreateInstanceFrom(assemblyPath, typeof(TypeParser).FullName).Unwrap(); The last line of code is what blows up with the Unable to cast transparent proxy to type <type> error. Without the cast the code actually returns a TransparentProxy instance, but the cast is what blows up. In other words I AM in fact getting a TypeParser instance back but it can't be cast to the TypeParser type that is loaded in the current AppDomain. Finding the Problem To see what's going on I tried using the .NET 4.0 dynamic type on the result and lo and behold it worked with dynamic - the value returned is actually a TypeParser instance: Assembly assembly = Assembly.GetExecutingAssembly(); string assemblyPath = Assembly.GetExecutingAssembly().Location; object objparser = this.LocalAppDomain.CreateInstanceFrom(assemblyPath, typeof(TypeParser).FullName).Unwrap(); // dynamic works dynamic dynParser = objparser; string info = dynParser.GetVersionInfo(); // method call works // casting fails parser = (TypeParser)objparser; So clearly a TypeParser type is coming back, but nevertheless it's not the right one. Hmmm… mysterious.Another couple of tries reveal the problem however:// works dynamic dynParser = objparser; string info = dynParser.GetVersionInfo(); // method call works // c:\wwapps\wwhelp\wwReflection20.dll (Current Execution Folder) string info3 = typeof(TypeParser).Assembly.CodeBase; // c:\program files\vfp9\wwReflection20.dll (my COM client EXE's folder) string info4 = dynParser.GetType().Assembly.CodeBase; // fails parser = (TypeParser)objparser; As you can see the second value is coming from a totally different assembly. Note that this is even though I EXPLICITLY SPECIFIED an assembly path to load the assembly from! Instead .NET decided to load the assembly from the original ApplicationBase folder. Ouch! How I actually tracked this down was a little more tedious: I added a method like this to both the factory and the instance types and then compared notes:public string GetVersionInfo() { return ".NET Version: " + Environment.Version.ToString() + "\r\n" + "wwReflection Assembly: " + typeof(TypeParserFactory).Assembly.CodeBase.Replace("file:///", "").Replace("/", "\\") + "\r\n" + "Assembly Cur Dir: " + Directory.GetCurrentDirectory() + "\r\n" + "ApplicationBase: " + AppDomain.CurrentDomain.SetupInformation.ApplicationBase + "\r\n" + "App Domain: " + AppDomain.CurrentDomain.FriendlyName + "\r\n"; } For the factory I got: .NET Version: 4.0.30319.239wwReflection Assembly: c:\wwapps\wwhelp\bin\wwreflection20.dllAssembly Cur Dir: c:\wwapps\wwhelpApplicationBase: C:\Programs\vfp9\App Domain: wwReflection534cfa1f For the instance type I got: .NET Version: 4.0.30319.239wwReflection Assembly: C:\\Programs\\vfp9\wwreflection20.dllAssembly Cur Dir: c:\\wwapps\\wwhelpApplicationBase: C:\\Programs\\vfp9\App Domain: wwDotNetBridge_56006605 which clearly shows the problem. You can see that both are loading from different appDomains but the each is loading the assembly from a different location. Probably a better solution yet (for ANY kind of assembly loading problem) is to use the .NET Fusion Log Viewer to trace assembly loads.The Fusion viewer will show a load trace for each assembly loaded and where it's looking to find it. Here's what the viewer looks like: The last trace above that I found for the second wwReflection20 load (the one that is wonky) looks like this:*** Assembly Binder Log Entry (1/13/2012 @ 3:06:49 AM) *** The operation was successful. Bind result: hr = 0x0. The operation completed successfully. Assembly manager loaded from: C:\Windows\Microsoft.NET\Framework\V4.0.30319\clr.dll Running under executable c:\programs\vfp9\vfp9.exe --- A detailed error log follows. === Pre-bind state information === LOG: User = Ras\ricks LOG: DisplayName = wwReflection20, Version=4.61.0.0, Culture=neutral, PublicKeyToken=null (Fully-specified) LOG: Appbase = file:///C:/Programs/vfp9/ LOG: Initial PrivatePath = NULL LOG: Dynamic Base = NULL LOG: Cache Base = NULL LOG: AppName = vfp9.exe Calling assembly : (Unknown). === LOG: This bind starts in default load context. LOG: Using application configuration file: C:\Programs\vfp9\vfp9.exe.Config LOG: Using host configuration file: LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\V4.0.30319\config\machine.config. LOG: Policy not being applied to reference at this time (private, custom, partial, or location-based assembly bind). LOG: Attempting download of new URL file:///C:/Programs/vfp9/wwReflection20.DLL. LOG: Assembly download was successful. Attempting setup of file: C:\Programs\vfp9\wwReflection20.dll LOG: Entering run-from-source setup phase. LOG: Assembly Name is: wwReflection20, Version=4.61.0.0, Culture=neutral, PublicKeyToken=null LOG: Binding succeeds. Returns assembly from C:\Programs\vfp9\wwReflection20.dll. LOG: Assembly is loaded in default load context. WRN: The same assembly was loaded into multiple contexts of an application domain: WRN: Context: Default | Domain ID: 2 | Assembly Name: wwReflection20, Version=4.61.0.0, Culture=neutral, PublicKeyToken=null WRN: Context: LoadFrom | Domain ID: 2 | Assembly Name: wwReflection20, Version=4.61.0.0, Culture=neutral, PublicKeyToken=null WRN: This might lead to runtime failures. WRN: It is recommended to inspect your application on whether this is intentional or not. WRN: See whitepaper http://go.microsoft.com/fwlink/?LinkId=109270 for more information and common solutions to this issue. Notice that the fusion log clearly shows that the .NET loader makes no attempt to even load the assembly from the path I explicitly specified. Remember your Assembly Locations As mentioned earlier all failures I've seen like this ultimately resulted from different versions of the same type being available in the two AppDomains. At first sight that seems ridiculous - how could the types be different and why would you have multiple assemblies - but there are actually a number of scenarios where it's quite possible to have multiple copies of the same assembly floating around in multiple places. If you're hosting different environments (like hosting the Razor Engine, or ASP.NET Runtime for example) it's common to create a private BIN folder and it's important to make sure that there's no overlap of assemblies. In my case of Html Help Builder the problem started because I'm using COM interop to access the .NET assembly and the above code. COM Interop has very specific requirements on where assemblies can be found and because I was mucking around with the loader code today, I ended up moving assemblies around to a new location for explicit loading. The explicit load works in the main AppDomain, but failed in the remote domain as I showed. The solution here was simple enough: Delete the extraneous assembly which was left around by accident. Not a common problem, but one that when it bites is pretty nasty to figure out because it seems so unlikely that types wouldn't match. I know I've run into this a few times and writing this down hopefully will make me remember in the future rather than poking around again for an hour trying to debug the issue as I did today. Hopefully it'll save some of you some time as well in the future.© Rick Strahl, West Wind Technologies, 2005-2012Posted in .NET  COM   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • ADIOS Weblogs

    - by kashyapa
    I have been blogging on Weblogs.asp.net for a while now. I don't remember when actually i got a berth on to Weblogs. I think it was MS Joe – Joe Stagner way back somewhere in 2005 or sometime around that time frame (i don't remember the exact dates) that he had opened up weblogs.asp.net blog space. I remember sending an email to him and i had got a space for myself. So far weblogs has been a great starting platform for me. After close to a decade in the industry (this is my 9 year in the industry) i finally realized that i too can write and i have been lately passionate about writing. So far i just have 15 posts under my belt and close to 5 community speaking sessions. I have been lately enjoying writing and community things that i decided to have my own identity on the web. Yes i have purchased my own domain and i have taken up a hosting for my own blog. My new web identity would be 2 domains under my name – www.kashyapas.com and www.lohithgn.com. I will be discontinuing writing on weblogs.asp.net and will be fulltime at www.kashyapas.com. My RSS feed at weblogs.asp.net has been redirected to point to my new site. So whoever had subscribed to my RSS will still be getting the updated content from my new site. So do drop into my new home and let me know your feedback. As i say always – Happy coding and Code with passion !

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  • Speaking in Sweden in April

    - by Fabrice Marguerie
    As this is my first post in 2011, I wish you all the best for this new year. I don't know for you, but it will be a year of changes for me. I'll tell you more about that when the time comes. For the time being, I just wanted to announce my next speaking engagement: I'll be presenting at SDC2011, the Scandinavian Developer Conference. This event will take place on April 4 and 5 in Göteborg, Sweden. My session will be based on my article about memory leaks: How to detect and avoid memory and resources leaks in .NET applicationsDuring this session we will analyze the most common leak sources in .NET applications and we will see how to detect them in practice. We will demonstrate with live examples several tools that can help you to troubleshoot your applications. The goal of this session is to help you fix and avoid leaks in your .NET applications, whether they are built with Windows Forms, WPF, Silverlight, ASP.NET, or as console or Windows services. You will also get advices on how to improve your applications so they become less greedy. I hope to see you there if you're around in April :-)

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  • How to set SGEN toolpath in Msbuild to target 3.5 framework

    - by Craig Shearer
    I've just upgraded a project from VS2008 to VS2010 but I'm still targeting the 3.5 framework. In my project file I have a custom task to run SGEN to generate my XmlSerializers.dll. However the version of sgen being run targets the 4.0 framework. As a result, when I run my application I get the error message: "Could not load file or assembly 'XXXX.XXXX.XmlSerializers' or one of its dependencies. This assembly is built by a runtime newer than the currently loaded runtime and cannot be loaded." The Sgen task looks like this: <Target Name="AfterBuild" DependsOnTargets="AssignTargetPaths;Compile;ResolveKeySource" Inputs="$(MSBuildAllProjects);@(IntermediateAssembly)" Outputs="$(OutputPath)$(_SGenDllName)"> <!-- Delete the file because I can't figure out how to force the SGen task. --> <Delete Files="$(TargetDir)$(TargetName).XmlSerializers.dll" ContinueOnError="true" /> <SGen BuildAssemblyName="$(TargetFileName)" BuildAssemblyPath="$(OutputPath)" References="@(ReferencePath)" ShouldGenerateSerializer="true" UseProxyTypes="false" KeyContainer="$(KeyContainerName)" KeyFile="$(KeyOriginatorFile)" DelaySign="$(DelaySign)" ToolPath="$(SGenToolPath)"> <Output TaskParameter="SerializationAssembly" ItemName="SerializationAssembly" /> </SGen> </Target> There's the ToolPath="$(SGenToolPath)". How do I make it run the version that targets 3.5? There's a similar question here but it doesn't help me much.

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  • Java Sound API: Capturing sound output from a Target Port

    - by Kyle Kampy
    I'm writing a simple piece of software that streams audio over LAN. I have all of the network parts implemented, but what I'm stumbling on is using the Java Sound API. I have successfully captured audio from the microphone, and line-in, but I can't seem to capture from any target ports, like the speakers. My question is, is it possible to capture from the Master target port? Here is the piece of code that works on initializing the line. private boolean startCapture(){ try{ DataLine.Info info = new DataLine.Info( TargetDataLine.class, format); line = (TargetDataLine)AudioSystem.getLine(info); audioBuffer = new byte[bufferSize]; line.open(format); line.start(); return true; }catch(Exception e){ System.out.println("Exception thrown when capturing audio:\n" + e); return false; } } Running the code like this will just use the microphone as my line. Here is info about my sound system. Most important is probably the fact that I'm running Linux. Thanks in advance for any and all help you can give me.

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  • Should a new language compiler target the JVM?

    - by Pindatjuh
    I'm developing a new language. My initial target was to compile to native x86 for the Windows platform, but now I am in doubt. I've seen some new languages target the JVM (most notable Scala and Clojure). Ofcourse it's not possible to port every language easily to the JVM; to do so, it may lead to small changes to the language and it's design. So that's the reason behind this doubt, and thus this question: Is targetting the JVM a good idea, when creating a compiler for a new language? Or should I stick with x86? I have experience in generating JVM bytecode. Are there any workarounds to JVM's GC? The language has deterministic implicit memory management. How to produce JIT-compatible bytecode, such that it will get the highest speedup? Is it similar to compiling for IA-32, such as the 4-1-1 muops pattern on Pentium? I can imagine some advantages (please correct me if I'm wrong): JVM bytecode is easier than x86. Like x86 communicates with Windows, JVM communicates with the Java Foundation Classes. To provide I/O, Threading, GUI, etc. Implementing "lightweight"-threads.I've seen a very clever implementation of this at http://www.malhar.net/sriram/kilim/. Most advantages of the Java Runtime (portability, etc.) The disadvantages, as I imagined, are: Less freedom? On x86 it'll be more easy to create low-level constructs, while JVM has a higher level (more abstract) processor. Most disadvantages of the Java Runtime (no native dynamic typing, etc.)

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  • xcode project-/target-settings-syntax for linker flag force_load on iPhone

    - by Kaiserludi
    Hi all. I am confronted with the double bind, that on the one hand for one of the 3rd party static libraries, my iPhone application uses, the linker flag -all_load has to be set in the application project- or target settings, otherwise the app crashes at runtime not finding some symbols, called internally from the lib, on the other hand for another 3rd party static lib -all_load must not be set on application level, or the app won't build thanks to a "duplicate symbols"-linker error. To solve this issue I now want to use force_load instant of load_all, as it due to documentation it does the same like all_load, but only for the passed path or lib-file, instead of all libs. The problem with force_load is, I do not have a clue, how to pass a path or file as parameter with it, when passing it via xcode project- or target-settings. All syntax-possibilities coming to my mind either lead into xcode thinking its another linker flag instead of a parameter to the previous one, or the linker is throwing syntax related errors or the flag simply does nothing at all in comparison to not being set. I also opened the .pbxproj-file in a text-editor to edit it to the correct command line syntax manually, but when reloading the project with xcode, it auto changes the syntax into interpreting the parameter to force_load as a separate flag. Anyone having an idea on this issue? Thx, Kaiserludi.

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  • How to handle build rule with unknown targets in OMake when target list generator is built

    - by Michael E
    I have a project which uses OMake for its build system, and I am trying to handle a rather tough corner case. I have some definition files and a tool which can take these definition files and create GraphViz files. There are two problems, though: Each definition file can produce multiple graphs, and the list of graphs it can produce is encoded in the file. My dump tool does have a -list option which lists all the graphs a definition file will produce. This dump tool is built in the source tree. I want this list available in the OMakefile so I can use other rules to convert the DOT files to SVG, and have a phony target depend on all the SVGs (goal: a single build command which builds SVG descriptions of all my graphs). If I only had the first problem, it would be easy - I would run the tool to build a list, and then use that list to build a target which invokes the dumper to output the GraphViz files. However, I am rather stuck on forcing the dump tool to be built before it is needed. If this were make, I would just run make recursively to build the dump tool. OMake does not allow recursive invocation, however, and the build function is only usable from osh. Any suggestions for a good solution to this problem?

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  • make target is never determined up to date

    - by Michael
    Cygwin make always processing $(chrome_jar_file) target, after first successful build. So I never get up to date message and always see commands for $(chrome_jar_file) are executing. However it happens only on Windows 7. On Windows XP once it built and intact, no more builds. I narrowed down the issue to one prerequisite - $(jar_target_dir). Here is part of the code # The location where the JAR file will be created. jar_target_dir := $(build_dir)/chrome # The main chrome JAR file. chrome_jar_file := $(jar_target_dir)/$(extension_name).jar # The root of the JAR sources. jar_source_root := chrome # The sources for the JAR file. jar_sources := bla #... some files, doesn't matter jar_sources_no_dir := $(subst $(jar_source_root)/,,$(jar_sources)) $(chrome_jar_file): $(jar_sources) $(jar_target_dir) @echo "Creating chrome JAR file." @cd $(jar_source_root); $(ZIP) ../$(chrome_jar_file) $(jar_sources_no_dir) @echo "Creating chrome JAR file. Done!" $(jar_target_dir): $(build_dir) echo "Creating jar target dir..." if [ ! -x $(jar_target_dir) ]; \ then \ mkdir $(jar_target_dir); \ fi $(build_dir): @if [ ! -x $(build_dir) ]; \ then \ mkdir $(build_dir); \ fi so if I just remove $(jar_target_dir) from $(chrome_jar_file) rule, it works fine.

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  • WCF REST Service Activation Errors when AspNetCompatibility is enabled

    - by Rick Strahl
    I’m struggling with an interesting problem with WCF REST since last night and I haven’t been able to track this down. I have a WCF REST Service set up and when accessing the .SVC file it crashes with a version mismatch for System.ServiceModel: Server Error in '/AspNetClient' Application. Could not load type 'System.ServiceModel.Activation.HttpHandler' from assembly 'System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.TypeLoadException: Could not load type 'System.ServiceModel.Activation.HttpHandler' from assembly 'System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [TypeLoadException: Could not load type 'System.ServiceModel.Activation.HttpHandler' from assembly 'System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.] System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMarkHandle stackMark, Boolean loadTypeFromPartialName, ObjectHandleOnStack type) +0 System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark, Boolean loadTypeFromPartialName) +95 System.RuntimeType.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark) +54 System.Type.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase) +65 System.Web.Compilation.BuildManager.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase) +69 System.Web.Configuration.HandlerFactoryCache.GetTypeWithAssert(String type) +38 System.Web.Configuration.HandlerFactoryCache.GetHandlerType(String type) +13 System.Web.Configuration.HandlerFactoryCache..ctor(String type) +19 System.Web.HttpApplication.GetFactory(String type) +81 System.Web.MaterializeHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +223 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +184 Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.1 What’s really odd about this is that it crashes only if it runs inside of IIS (it works fine in Cassini) and only if ASP.NET Compatibility is enabled in web.config:<serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true" /> Arrrgh!!!!! After some experimenting and some help from Glenn Block and his team mates I was able to track down the problem in ApplicationHost.config. Specifically the problem was that there were multiple *.svc mappings in the ApplicationHost.Config file and the older 2.0 runtime specific versions weren’t marked for the proper runtime. Because these handlers show up at the top of the list they execute first resulting in assembly load errors for the wrong version assembly. To fix this problem I ended up making a couple changes in applicationhost.config. On the machine level root’s Handler mappings I had an entry that looked like this:<add name="svc-Integrated" path="*.svc" verb="*" type="System.ServiceModel.Activation.HttpHandler, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" preCondition="integratedMode" /> and it needs to be changed to this:<add name="svc-Integrated" path="*.svc" verb="*" type="System.ServiceModel.Activation.HttpHandler, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" preCondition="integratedMode,runtimeVersionv2.0" />Notice the explicit runtime version assignment in the preCondition attribute which is key to keep ASP.NET 4.0 from executing that handler. The key here is that the runtime version needs to be set explicitly so that the various *.svc handlers don’t fire only in the order defined which in case of a .NET 4.0 app with the original setting would result in an incompatible version of System.ComponentModel to load.What was really hard to track this down is that even when looking in the debugger when launching the Web app, the AppDomain assembly loads showed System.ServiceModel V4.0 starting up just fine. Apparently the ASP.NET runtime load occurs at a different point and that’s when things break.So how did this break? According to the Microsoft folks it’s some older tools that got installed that change the default service handlers. There’s a blog entry that points at this problem with more detail:http://blogs.iis.net/webtopics/archive/2010/04/28/system-typeloadexception-for-system-servicemodel-activation-httpmodule-in-asp-net-4.aspxNote that I tried running aspnet_regiis and that did not fix the problem for me. I had to manually change the entries in applicationhost.config.   © Rick Strahl, West Wind Technologies, 2005-2011Posted in AJAX   ASP.NET  WCF  

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  • C#/.NET Little Wonders: The Generic Func Delegates

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Back in one of my three original “Little Wonders” Trilogy of posts, I had listed generic delegates as one of the Little Wonders of .NET.  Later, someone posted a comment saying said that they would love more detail on the generic delegates and their uses, since my original entry just scratched the surface of them. Last week, I began our look at some of the handy generic delegates built into .NET with a description of delegates in general, and the Action family of delegates.  For this week, I’ll launch into a look at the Func family of generic delegates and how they can be used to support generic, reusable algorithms and classes. Quick Delegate Recap Delegates are similar to function pointers in C++ in that they allow you to store a reference to a method.  They can store references to either static or instance methods, and can actually be used to chain several methods together in one delegate. Delegates are very type-safe and can be satisfied with any standard method, anonymous method, or a lambda expression.  They can also be null as well (refers to no method), so care should be taken to make sure that the delegate is not null before you invoke it. Delegates are defined using the keyword delegate, where the delegate’s type name is placed where you would typically place the method name: 1: // This delegate matches any method that takes string, returns nothing 2: public delegate void Log(string message); This delegate defines a delegate type named Log that can be used to store references to any method(s) that satisfies its signature (whether instance, static, lambda expression, etc.). Delegate instances then can be assigned zero (null) or more methods using the operator = which replaces the existing delegate chain, or by using the operator += which adds a method to the end of a delegate chain: 1: // creates a delegate instance named currentLogger defaulted to Console.WriteLine (static method) 2: Log currentLogger = Console.Out.WriteLine; 3:  4: // invokes the delegate, which writes to the console out 5: currentLogger("Hi Standard Out!"); 6:  7: // append a delegate to Console.Error.WriteLine to go to std error 8: currentLogger += Console.Error.WriteLine; 9:  10: // invokes the delegate chain and writes message to std out and std err 11: currentLogger("Hi Standard Out and Error!"); While delegates give us a lot of power, it can be cumbersome to re-create fairly standard delegate definitions repeatedly, for this purpose the generic delegates were introduced in various stages in .NET.  These support various method types with particular signatures. Note: a caveat with generic delegates is that while they can support multiple parameters, they do not match methods that contains ref or out parameters. If you want to a delegate to represent methods that takes ref or out parameters, you will need to create a custom delegate. We’ve got the Func… delegates Just like it’s cousin, the Action delegate family, the Func delegate family gives us a lot of power to use generic delegates to make classes and algorithms more generic.  Using them keeps us from having to define a new delegate type when need to make a class or algorithm generic. Remember that the point of the Action delegate family was to be able to perform an “action” on an item, with no return results.  Thus Action delegates can be used to represent most methods that take 0 to 16 arguments but return void.  You can assign a method The Func delegate family was introduced in .NET 3.5 with the advent of LINQ, and gives us the power to define a function that can be called on 0 to 16 arguments and returns a result.  Thus, the main difference between Action and Func, from a delegate perspective, is that Actions return nothing, but Funcs return a result. The Func family of delegates have signatures as follows: Func<TResult> – matches a method that takes no arguments, and returns value of type TResult. Func<T, TResult> – matches a method that takes an argument of type T, and returns value of type TResult. Func<T1, T2, TResult> – matches a method that takes arguments of type T1 and T2, and returns value of type TResult. Func<T1, T2, …, TResult> – and so on up to 16 arguments, and returns value of type TResult. These are handy because they quickly allow you to be able to specify that a method or class you design will perform a function to produce a result as long as the method you specify meets the signature. For example, let’s say you were designing a generic aggregator, and you wanted to allow the user to define how the values will be aggregated into the result (i.e. Sum, Min, Max, etc…).  To do this, we would ask the user of our class to pass in a method that would take the current total, the next value, and produce a new total.  A class like this could look like: 1: public sealed class Aggregator<TValue, TResult> 2: { 3: // holds method that takes previous result, combines with next value, creates new result 4: private Func<TResult, TValue, TResult> _aggregationMethod; 5:  6: // gets or sets the current result of aggregation 7: public TResult Result { get; private set; } 8:  9: // construct the aggregator given the method to use to aggregate values 10: public Aggregator(Func<TResult, TValue, TResult> aggregationMethod = null) 11: { 12: if (aggregationMethod == null) throw new ArgumentNullException("aggregationMethod"); 13:  14: _aggregationMethod = aggregationMethod; 15: } 16:  17: // method to add next value 18: public void Aggregate(TValue nextValue) 19: { 20: // performs the aggregation method function on the current result and next and sets to current result 21: Result = _aggregationMethod(Result, nextValue); 22: } 23: } Of course, LINQ already has an Aggregate extension method, but that works on a sequence of IEnumerable<T>, whereas this is designed to work more with aggregating single results over time (such as keeping track of a max response time for a service). We could then use this generic aggregator to find the sum of a series of values over time, or the max of a series of values over time (among other things): 1: // creates an aggregator that adds the next to the total to sum the values 2: var sumAggregator = new Aggregator<int, int>((total, next) => total + next); 3:  4: // creates an aggregator (using static method) that returns the max of previous result and next 5: var maxAggregator = new Aggregator<int, int>(Math.Max); So, if we were timing the response time of a web method every time it was called, we could pass that response time to both of these aggregators to get an idea of the total time spent in that web method, and the max time spent in any one call to the web method: 1: // total will be 13 and max 13 2: int responseTime = 13; 3: sumAggregator.Aggregate(responseTime); 4: maxAggregator.Aggregate(responseTime); 5:  6: // total will be 20 and max still 13 7: responseTime = 7; 8: sumAggregator.Aggregate(responseTime); 9: maxAggregator.Aggregate(responseTime); 10:  11: // total will be 40 and max now 20 12: responseTime = 20; 13: sumAggregator.Aggregate(responseTime); 14: maxAggregator.Aggregate(responseTime); The Func delegate family is useful for making generic algorithms and classes, and in particular allows the caller of the method or user of the class to specify a function to be performed in order to generate a result. What is the result of a Func delegate chain? If you remember, we said earlier that you can assign multiple methods to a delegate by using the += operator to chain them.  So how does this affect delegates such as Func that return a value, when applied to something like the code below? 1: Func<int, int, int> combo = null; 2:  3: // What if we wanted to aggregate the sum and max together? 4: combo += (total, next) => total + next; 5: combo += Math.Max; 6:  7: // what is the result? 8: var comboAggregator = new Aggregator<int, int>(combo); Well, in .NET if you chain multiple methods in a delegate, they will all get invoked, but the result of the delegate is the result of the last method invoked in the chain.  Thus, this aggregator would always result in the Math.Max() result.  The other chained method (the sum) gets executed first, but it’s result is thrown away: 1: // result is 13 2: int responseTime = 13; 3: comboAggregator.Aggregate(responseTime); 4:  5: // result is still 13 6: responseTime = 7; 7: comboAggregator.Aggregate(responseTime); 8:  9: // result is now 20 10: responseTime = 20; 11: comboAggregator.Aggregate(responseTime); So remember, you can chain multiple Func (or other delegates that return values) together, but if you do so you will only get the last executed result. Func delegates and co-variance/contra-variance in .NET 4.0 Just like the Action delegate, as of .NET 4.0, the Func delegate family is contra-variant on its arguments.  In addition, it is co-variant on its return type.  To support this, in .NET 4.0 the signatures of the Func delegates changed to: Func<out TResult> – matches a method that takes no arguments, and returns value of type TResult (or a more derived type). Func<in T, out TResult> – matches a method that takes an argument of type T (or a less derived type), and returns value of type TResult(or a more derived type). Func<in T1, in T2, out TResult> – matches a method that takes arguments of type T1 and T2 (or less derived types), and returns value of type TResult (or a more derived type). Func<in T1, in T2, …, out TResult> – and so on up to 16 arguments, and returns value of type TResult (or a more derived type). Notice the addition of the in and out keywords before each of the generic type placeholders.  As we saw last week, the in keyword is used to specify that a generic type can be contra-variant -- it can match the given type or a type that is less derived.  However, the out keyword, is used to specify that a generic type can be co-variant -- it can match the given type or a type that is more derived. On contra-variance, if you are saying you need an function that will accept a string, you can just as easily give it an function that accepts an object.  In other words, if you say “give me an function that will process dogs”, I could pass you a method that will process any animal, because all dogs are animals.  On the co-variance side, if you are saying you need a function that returns an object, you can just as easily pass it a function that returns a string because any string returned from the given method can be accepted by a delegate expecting an object result, since string is more derived.  Once again, in other words, if you say “give me a method that creates an animal”, I can pass you a method that will create a dog, because all dogs are animals. It really all makes sense, you can pass a more specific thing to a less specific parameter, and you can return a more specific thing as a less specific result.  In other words, pay attention to the direction the item travels (parameters go in, results come out).  Keeping that in mind, you can always pass more specific things in and return more specific things out. For example, in the code below, we have a method that takes a Func<object> to generate an object, but we can pass it a Func<string> because the return type of object can obviously accept a return value of string as well: 1: // since Func<object> is co-variant, this will access Func<string>, etc... 2: public static string Sequence(int count, Func<object> generator) 3: { 4: var builder = new StringBuilder(); 5:  6: for (int i=0; i<count; i++) 7: { 8: object value = generator(); 9: builder.Append(value); 10: } 11:  12: return builder.ToString(); 13: } Even though the method above takes a Func<object>, we can pass a Func<string> because the TResult type placeholder is co-variant and accepts types that are more derived as well: 1: // delegate that's typed to return string. 2: Func<string> stringGenerator = () => DateTime.Now.ToString(); 3:  4: // This will work in .NET 4.0, but not in previous versions 5: Sequence(100, stringGenerator); Previous versions of .NET implemented some forms of co-variance and contra-variance before, but .NET 4.0 goes one step further and allows you to pass or assign an Func<A, BResult> to a Func<Y, ZResult> as long as A is less derived (or same) as Y, and BResult is more derived (or same) as ZResult. Sidebar: The Func and the Predicate A method that takes one argument and returns a bool is generally thought of as a predicate.  Predicates are used to examine an item and determine whether that item satisfies a particular condition.  Predicates are typically unary, but you may also have binary and other predicates as well. Predicates are often used to filter results, such as in the LINQ Where() extension method: 1: var numbers = new[] { 1, 2, 4, 13, 8, 10, 27 }; 2:  3: // call Where() using a predicate which determines if the number is even 4: var evens = numbers.Where(num => num % 2 == 0); As of .NET 3.5, predicates are typically represented as Func<T, bool> where T is the type of the item to examine.  Previous to .NET 3.5, there was a Predicate<T> type that tended to be used (which we’ll discuss next week) and is still supported, but most developers recommend using Func<T, bool> now, as it prevents confusion with overloads that accept unary predicates and binary predicates, etc.: 1: // this seems more confusing as an overload set, because of Predicate vs Func 2: public static SomeMethod(Predicate<int> unaryPredicate) { } 3: public static SomeMethod(Func<int, int, bool> binaryPredicate) { } 4:  5: // this seems more consistent as an overload set, since just uses Func 6: public static SomeMethod(Func<int, bool> unaryPredicate) { } 7: public static SomeMethod(Func<int, int, bool> binaryPredicate) { } Also, even though Predicate<T> and Func<T, bool> match the same signatures, they are separate types!  Thus you cannot assign a Predicate<T> instance to a Func<T, bool> instance and vice versa: 1: // the same method, lambda expression, etc can be assigned to both 2: Predicate<int> isEven = i => (i % 2) == 0; 3: Func<int, bool> alsoIsEven = i => (i % 2) == 0; 4:  5: // but the delegate instances cannot be directly assigned, strongly typed! 6: // ERROR: cannot convert type... 7: isEven = alsoIsEven; 8:  9: // however, you can assign by wrapping in a new instance: 10: isEven = new Predicate<int>(alsoIsEven); 11: alsoIsEven = new Func<int, bool>(isEven); So, the general advice that seems to come from most developers is that Predicate<T> is still supported, but we should use Func<T, bool> for consistency in .NET 3.5 and above. Sidebar: Func as a Generator for Unit Testing One area of difficulty in unit testing can be unit testing code that is based on time of day.  We’d still want to unit test our code to make sure the logic is accurate, but we don’t want the results of our unit tests to be dependent on the time they are run. One way (of many) around this is to create an internal generator that will produce the “current” time of day.  This would default to returning result from DateTime.Now (or some other method), but we could inject specific times for our unit testing.  Generators are typically methods that return (generate) a value for use in a class/method. For example, say we are creating a CacheItem<T> class that represents an item in the cache, and we want to make sure the item shows as expired if the age is more than 30 seconds.  Such a class could look like: 1: // responsible for maintaining an item of type T in the cache 2: public sealed class CacheItem<T> 3: { 4: // helper method that returns the current time 5: private static Func<DateTime> _timeGenerator = () => DateTime.Now; 6:  7: // allows internal access to the time generator 8: internal static Func<DateTime> TimeGenerator 9: { 10: get { return _timeGenerator; } 11: set { _timeGenerator = value; } 12: } 13:  14: // time the item was cached 15: public DateTime CachedTime { get; private set; } 16:  17: // the item cached 18: public T Value { get; private set; } 19:  20: // item is expired if older than 30 seconds 21: public bool IsExpired 22: { 23: get { return _timeGenerator() - CachedTime > TimeSpan.FromSeconds(30.0); } 24: } 25:  26: // creates the new cached item, setting cached time to "current" time 27: public CacheItem(T value) 28: { 29: Value = value; 30: CachedTime = _timeGenerator(); 31: } 32: } Then, we can use this construct to unit test our CacheItem<T> without any time dependencies: 1: var baseTime = DateTime.Now; 2:  3: // start with current time stored above (so doesn't drift) 4: CacheItem<int>.TimeGenerator = () => baseTime; 5:  6: var target = new CacheItem<int>(13); 7:  8: // now add 15 seconds, should still be non-expired 9: CacheItem<int>.TimeGenerator = () => baseTime.AddSeconds(15); 10:  11: Assert.IsFalse(target.IsExpired); 12:  13: // now add 31 seconds, should now be expired 14: CacheItem<int>.TimeGenerator = () => baseTime.AddSeconds(31); 15:  16: Assert.IsTrue(target.IsExpired); Now we can unit test for 1 second before, 1 second after, 1 millisecond before, 1 day after, etc.  Func delegates can be a handy tool for this type of value generation to support more testable code.  Summary Generic delegates give us a lot of power to make truly generic algorithms and classes.  The Func family of delegates is a great way to be able to specify functions to calculate a result based on 0-16 arguments.  Stay tuned in the weeks that follow for other generic delegates in the .NET Framework!   Tweet Technorati Tags: .NET, C#, CSharp, Little Wonders, Generics, Func, Delegates

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  • MVC2 EditorTemplate for DropDownList

    - by tschreck
    I've spent the majority of the past week knee deep in the new templating functionality baked into MVC2. I had a hard time trying to get a DropDownList template working. The biggest problem I've been working to solve is how to get the source data for the drop down list to the template. I saw a lot of examples where you can put the source data in the ViewData dictionary (ViewData["DropDownSourceValuesKey"]) then retrieve them in the template itself (var sourceValues = ViewData["DropDownSourceValuesKey"];) This works, but I did not like having a silly string as the lynch pin for making this work. Below is an approach I've come up with and wanted to get opinions on this approach: here are my design goals: The view model should contain the source data for the drop down list Limit Silly Strings Not use ViewData dictionary Controller is responsible for filling the property with the source data for the drop down list Here's my View Model: public class CustomerViewModel { [ScaffoldColumn(false)] public String CustomerCode{ get; set; } [UIHint("DropDownList")] [DropDownList(DropDownListTargetProperty = "CustomerCode"] [DisplayName("Customer Code")] public IEnumerable<SelectListItem> CustomerCodeList { get; set; } public String FirstName { get; set; } public String LastName { get; set; } public String PhoneNumber { get; set; } public String Address1 { get; set; } public String Address2 { get; set; } public String City { get; set; } public String State { get; set; } public String Zip { get; set; } } My View Model has a CustomerCode property which is a value that the user selects from a list of values. I have a CustomerCodeList property that is a list of possible CustomerCode values and is the source for a drop down list. I've created a DropDownList attribute with a DropDownListTargetProperty. DropDownListTargetProperty points to the property which will be populated based on the user selection from the generated drop down (in this case, the CustomerCode property). Notice that the CustomerCode property has [ScaffoldColumn(false)] which forces the generator to skip the field in the generated output. My DropDownList.ascx file will generate a dropdown list form element with the source data from the CustomerCodeList property. The generated dropdown list will use the value of the DropDownListTargetProperty from the DropDownList attribute as the Id and the Name attributes of the Select form element. So the generated code will look like this: <select id="CustomerCode" name="CustomerCode"> <option>... </select> This works out great because when the form is submitted, MVC will populate the target property with the selected value from the drop down list because the name of the generated dropdown list IS the target property. I kinda visualize it as the CustomerCodeList property is an extension of sorts of the CustomerCode property. I've coupled the source data to the property. Here's my code for the controller: public ActionResult Create() { //retrieve CustomerCodes from a datasource of your choosing List<CustomerCode> customerCodeList = modelService.GetCustomerCodeList(); CustomerViewModel viewModel= new CustomerViewModel(); viewModel.CustomerCodeList = customerCodeList.Select(s => new SelectListItem() { Text = s.CustomerCode, Value = s.CustomerCode, Selected = (s.CustomerCode == viewModel.CustomerCode) }).AsEnumerable(); return View(viewModel); } Here's my code for the DropDownListAttribute: namespace AutoForm.Attributes { public class DropDownListAttribute : Attribute { public String DropDownListTargetProperty { get; set; } } } Here's my code for the template (DropDownList.ascx): <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<IEnumerable<SelectListItem>>" %> <%@ Import Namespace="AutoForm.Attributes"%> <script runat="server"> DropDownListAttribute GetDropDownListAttribute() { var dropDownListAttribute = new DropDownListAttribute(); if (ViewData.ModelMetadata.AdditionalValues.ContainsKey("DropDownListAttribute")) { dropDownListAttribute = (DropDownListAttribute)ViewData.ModelMetadata.AdditionalValues["DropDownListAttribute"]; } return dropDownListAttribute; } </script> <% DropDownListAttribute attribute = GetDropDownListAttribute();%> <select id="<%= attribute.DropDownListTargetProperty %>" name="<%= attribute.DropDownListTargetProperty %>"> <% foreach(SelectListItem item in ViewData.Model) {%> <% if (item.Selected == true) {%> <option value="<%= item.Value %>" selected="true"><%= item.Text %></option> <% } %> <% else {%> <option value="<%= item.Value %>"><%= item.Text %></option> <% } %> <% } %> </select> I tried using the Html.DropDownList helper, but it would not allow me to change the Id and Name attributes of the generated Select element. NOTE: you have to override the CreateMetadata method of the DataAnnotationsModelMetadataProvider for the DropDownListAttribute. Here's the code for that: public class MetadataProvider : DataAnnotationsModelMetadataProvider { protected override ModelMetadata CreateMetadata(IEnumerable<Attribute> attributes, Type containerType, Func<object> modelAccessor, Type modelType, string propertyName) { var metadata = base.CreateMetadata(attributes, containerType, modelAccessor, modelType, propertyName); var additionalValues = attributes.OfType<DropDownListAttribute>().FirstOrDefault(); if (additionalValues != null) { metadata.AdditionalValues.Add("DropDownListAttribute", additionalValues); } return metadata; } } Then you have to make a call to the new MetadataProvider in Application_Start of Global.asax.cs: protected void Application_Start() { RegisterRoutes(RouteTable.Routes); ModelMetadataProviders.Current = new MetadataProvider(); } Well, I hope this makes sense and I hope this approach may save you some time. I'd like some feedback on this approach please. Is there a better approach?

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  • InternalsVisibleTo attribute and security vulnerability

    - by Sergey Litvinov
    I found one issue with InternalsVisibleTo attribute usage. The idea of InternalsVisibleTo attribute to allow some other assemblies to use internal classes\methods of this assembly. To make it work you need sign your assemblies. So, if other assemblies isn't specified in main assembly and if they have incorrect public key, then they can't use Internal members. But the issue in Reflection Emit type generation. For example, we have CorpLibrary1 assembly and it has such class: public class TestApi { internal virtual void DoSomething() { Console.WriteLine("Base DoSomething"); } public void DoApiTest() { // some internal logic // ... // call internal method DoSomething(); } } This assembly is marked with such attribute to allow another CorpLibrary2 to make inheritor for that TestAPI and override behaviour of DoSomething method. [assembly: InternalsVisibleTo("CorpLibrary2, PublicKey=0024000004800000940000000602000000240000525341310004000001000100434D9C5E1F9055BF7970B0C106AAA447271ECE0F8FC56F6AF3A906353F0B848A8346DC13C42A6530B4ED2E6CB8A1E56278E664E61C0D633A6F58643A7B8448CB0B15E31218FB8FE17F63906D3BF7E20B9D1A9F7B1C8CD11877C0AF079D454C21F24D5A85A8765395E5CC5252F0BE85CFEB65896EC69FCC75201E09795AAA07D0")] The issue is that I'm able to override this internal DoSomething method and break class logic. My steps to do it: Generate new assembly in runtime via AssemblyBuilder Get AssemblyName from CorpLibrary1 and copy PublikKey to new assembly Generate new assembly that will inherit TestApi class As PublicKey and name of generated assembly is the same as in InternalsVisibleTo, then we can generate new DoSomething method that will override internal method in TestAPI assembly Then we have another assembly that isn't related to this CorpLibrary1 and can't use internal members. We have such test code in it: class Program { static void Main(string[] args) { var builder = new FakeBuilder(InjectBadCode, "DoSomething", true); TestApi fakeType = builder.CreateFake(); fakeType.DoApiTest(); // it will display: // Inject bad code // Base DoSomething Console.ReadLine(); } public static void InjectBadCode() { Console.WriteLine("Inject bad code"); } } And this FakeBuilder class has such code: /// /// Builder that will generate inheritor for specified assembly and will overload specified internal virtual method /// /// Target type public class FakeBuilder { private readonly Action _callback; private readonly Type _targetType; private readonly string _targetMethodName; private readonly string _slotName; private readonly bool _callBaseMethod; public FakeBuilder(Action callback, string targetMethodName, bool callBaseMethod) { int randomId = new Random((int)DateTime.Now.Ticks).Next(); _slotName = string.Format("FakeSlot_{0}", randomId); _callback = callback; _targetType = typeof(TFakeType); _targetMethodName = targetMethodName; _callBaseMethod = callBaseMethod; } public TFakeType CreateFake() { // as CorpLibrary1 can't use code from unreferences assemblies, we need to store this Action somewhere. // And Thread is not bad place for that. It's not the best place as it won't work in multithread application, but it's just a sample LocalDataStoreSlot slot = Thread.AllocateNamedDataSlot(_slotName); Thread.SetData(slot, _callback); // then we generate new assembly with the same nameand public key as target assembly trusts by InternalsVisibleTo attribute var newTypeName = _targetType.Name + "Fake"; var targetAssembly = Assembly.GetAssembly(_targetType); AssemblyName an = new AssemblyName(); an.Name = GetFakeAssemblyName(targetAssembly); // copying public key to new generated assembly var assemblyName = targetAssembly.GetName(); an.SetPublicKey(assemblyName.GetPublicKey()); an.SetPublicKeyToken(assemblyName.GetPublicKeyToken()); AssemblyBuilder assemblyBuilder = Thread.GetDomain().DefineDynamicAssembly(an, AssemblyBuilderAccess.RunAndSave); ModuleBuilder moduleBuilder = assemblyBuilder.DefineDynamicModule(assemblyBuilder.GetName().Name, true); // create inheritor for specified type TypeBuilder typeBuilder = moduleBuilder.DefineType(newTypeName, TypeAttributes.Public | TypeAttributes.Class, _targetType); // LambdaExpression.CompileToMethod can be used only with static methods, so we need to create another method that will call our Inject method // we can do the same via ILGenerator, but expression trees are more easy to use MethodInfo methodInfo = CreateMethodInfo(moduleBuilder); MethodBuilder methodBuilder = typeBuilder.DefineMethod(_targetMethodName, MethodAttributes.Public | MethodAttributes.Virtual); ILGenerator ilGenerator = methodBuilder.GetILGenerator(); // call our static method that will call inject method ilGenerator.EmitCall(OpCodes.Call, methodInfo, null); // in case if we need, then we put call to base method if (_callBaseMethod) { var baseMethodInfo = _targetType.GetMethod(_targetMethodName, BindingFlags.NonPublic | BindingFlags.Instance); // place this to stack ilGenerator.Emit(OpCodes.Ldarg_0); // call the base method ilGenerator.EmitCall(OpCodes.Call, baseMethodInfo, new Type[0]); // return ilGenerator.Emit(OpCodes.Ret); } // generate type, create it and return to caller Type cheatType = typeBuilder.CreateType(); object type = Activator.CreateInstance(cheatType); return (TFakeType)type; } /// /// Get name of assembly from InternalsVisibleTo AssemblyName /// private static string GetFakeAssemblyName(Assembly assembly) { var internalsVisibleAttr = assembly.GetCustomAttributes(typeof(InternalsVisibleToAttribute), true).FirstOrDefault() as InternalsVisibleToAttribute; if (internalsVisibleAttr == null) { throw new InvalidOperationException("Assembly hasn't InternalVisibleTo attribute"); } var ind = internalsVisibleAttr.AssemblyName.IndexOf(","); var name = internalsVisibleAttr.AssemblyName.Substring(0, ind); return name; } /// /// Generate such code: /// ((Action)Thread.GetData(Thread.GetNamedDataSlot(_slotName))).Invoke(); /// private LambdaExpression MakeStaticExpressionMethod() { var allocateMethod = typeof(Thread).GetMethod("GetNamedDataSlot", BindingFlags.Static | BindingFlags.Public); var getDataMethod = typeof(Thread).GetMethod("GetData", BindingFlags.Static | BindingFlags.Public); var call = Expression.Call(allocateMethod, Expression.Constant(_slotName)); var getCall = Expression.Call(getDataMethod, call); var convCall = Expression.Convert(getCall, typeof(Action)); var invokExpr = Expression.Invoke(convCall); var lambda = Expression.Lambda(invokExpr); return lambda; } /// /// Generate static class with one static function that will execute Action from Thread NamedDataSlot /// private MethodInfo CreateMethodInfo(ModuleBuilder moduleBuilder) { var methodName = "_StaticTestMethod_" + _slotName; var className = "_StaticClass_" + _slotName; TypeBuilder typeBuilder = moduleBuilder.DefineType(className, TypeAttributes.Public | TypeAttributes.Class); MethodBuilder methodBuilder = typeBuilder.DefineMethod(methodName, MethodAttributes.Static | MethodAttributes.Public); LambdaExpression expression = MakeStaticExpressionMethod(); expression.CompileToMethod(methodBuilder); var type = typeBuilder.CreateType(); return type.GetMethod(methodName, BindingFlags.Static | BindingFlags.Public); } } remarks about sample: as we need to execute code from another assembly, CorpLibrary1 hasn't access to it, so we need to store this delegate somewhere. Just for testing I stored it in Thread NamedDataSlot. It won't work in multithreaded applications, but it's just a sample. I know that we use Reflection to get private\internal members of any class, but within reflection we can't override them. But this issue is allows anyone to override internal class\method if that assembly has InternalsVisibleTo attribute. I tested it on .Net 3.5\4 and it works for both of them. How does it possible to just copy PublicKey without private key and use it in runtime? The whole sample can be found there - https://github.com/sergey-litvinov/Tests_InternalsVisibleTo UPDATE1: That test code in Program and FakeBuilder classes hasn't access to key.sn file and that library isn't signed, so it hasn't public key at all. It just copying it from CorpLibrary1 by using Reflection.Emit

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  • Can I set Session timeout for a specified Session variable differently than other Session Variables

    - by Eppz
    I'd like to set the timeout on a specific Session Variable in a .Net web application, but leave other Session variables alone. Is this possible? Example: I have 5 Session Variables Session(var1) Session(var2) Session(var3) Session(var4) Session(var5) I want to set it so that Session(var1) through Session(var4) have a timeout of 8 hours (480 minutes), but Session(var5) has a timeout of 20 minutes. Can it be done?

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  • How to get fully qualified path of css file?

    - by Malcolm
    Hi, In ASP.NET MVC how do I get the fully qualified path to my css file by specifying the relative path. Eg Url.Content("~/Content/Print.css") This returns eg "/Content/Print.css" Where as I want http://www.mysite.com/Content/Printcss Understand the issue? Malcolm

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  • Bogus InvalidOperationException (in a DataServiceRequestException)

    - by Andrei Rinea
    I am having a hard time with ADO.NET Data Services (formerly code-named Astoria) as it gives me a bogus exception when I try to insert a new entity from the silverlight client and trying in a clean project (the same code) doesn't. In both cases, however, data is correctly inserted into the database. Using Fiddler (an HTTP debugger I could see that there is no problem in the HTTP communication as I will show later in this question. The code : var ctx = new MyProject123Entities(new Uri("http://andreiri/MyProject.Data/Data.svc")); var i = new Zone() { Data = DateTime.Now, IdElement = 1 }; ctx.AddToZone(i); i.StareZone = new StareZone() { IdStareZone = 1 }; ctx.AttachTo("StareZone", i.StareZone); ctx.SetLink(i, "StareZone", i.StareZone); i.TipZone = new TipZone() { IdTipZone = 1 }; ctx.AttachTo("TipZone", i.TipZone); ctx.SetLink(i, "TipZone", i.TipZone); i.User = new User() { IdUser = 2 }; ctx.AttachTo("User", i.User); ctx.SetLink(i, "User", i.User); ctx.BeginSaveChanges(r =] ctx.EndSaveChanges(r), null); when run the last line (ctx.EndSaveChanges(r)) will throw the following exception : System.Data.Services.Client.DataServiceRequestException was unhandled by user code Message="An error occurred while processing this request." StackTrace: at System.Data.Services.Client.DataServiceContext.SaveAsyncResult.HandleBatchResponse() at System.Data.Services.Client.DataServiceContext.SaveAsyncResult.EndRequest() at System.Data.Services.Client.DataServiceContext.EndSaveChanges(IAsyncResult asyncResult) at MyProject.MainPage.[]c__DisplayClassd6.[]c__DisplayClassd8.[dashboard_PostZoneCurent]b__d5(IAsyncResult r) at System.Data.Services.Client.BaseAsyncResult.HandleCompleted() at System.Data.Services.Client.DataServiceContext.SaveAsyncResult.HandleCompleted(PerRequest pereq) at System.Data.Services.Client.DataServiceContext.SaveAsyncResult.AsyncEndRead(IAsyncResult asyncResult) at System.IO.Stream.BeginRead(Byte[] buffer, Int32 offset, Int32 count, AsyncCallback callback, Object state) at System.Data.Services.Client.DataServiceContext.SaveAsyncResult.AsyncEndGetResponse(IAsyncResult asyncResult) InnerException: System.InvalidOperationException Message="The context is already tracking a different entity with the same resource Uri." StackTrace: at System.Data.Services.Client.DataServiceContext.AttachTo(Uri identity, Uri editLink, String etag, Object entity, Boolean fail) at System.Data.Services.Client.MaterializeAtom.MoveNext() at System.Data.Services.Client.DataServiceContext.HandleResponsePost(ResourceBox entry, MaterializeAtom materializer, Uri editLink, String etag) at System.Data.Services.Client.DataServiceContext.SaveAsyncResult.[HandleBatchResponse]d__1d.MoveNext() InnerException: (there is no further information regarding the exception although the ADo.NET Data Service is configured to return detailed informations) However the row is inserted correctly and completely in the database. Using fiddler I can see that the request : <?xml version="1.0" encoding="utf-8" standalone="yes"?> <entry xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices" xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata" xmlns="http://www.w3.org/2005/Atom"> <category scheme="http://schemas.microsoft.com/ado/2007/08/dataservices/scheme" term="MyProject123Model.Zone" /> <title /> <updated>2009-09-11T13:36:46.917157Z</updated> <author> <name /> </author> <id /> <link href="http://andreiri/MyProject.Data/Data.svc/StareZone(1)" rel="http://schemas.microsoft.com/ado/2007/08/dataservices/related/StareZone" type="application/atom+xml;type=entry" /> <link href="http://andreiri/MyProject.Data/Data.svc/TipZone(4)" rel="http://schemas.microsoft.com/ado/2007/08/dataservices/related/TipZone" type="application/atom+xml;type=entry" /> <link href="http://andreiri/MyProject.Data/Data.svc/User(4)" rel="http://schemas.microsoft.com/ado/2007/08/dataservices/related/User" type="application/atom+xml;type=entry" /> <content type="application/xml"> <m:properties> <d:Data m:type="Edm.DateTime">2009-09-11T16:36:40.588951+03:00</d:Data> <d:Detalii>aslkdfjasldkfj</d:Detalii> <d:IdElement m:type="Edm.Int32">1</d:IdElement> <d:IdZone m:type="Edm.Int32">0</d:IdZone> <d:X_Post m:type="Edm.Decimal">587647.4705</d:X_Post> <d:X_Repost m:type="Edm.Decimal" m:null="true" /> <d:Y_Post m:type="Edm.Decimal">325783.077599999</d:Y_Post> <d:Y_Repost m:type="Edm.Decimal" m:null="true" /> </m:properties> </content> </entry> is well accepted and a successful response is returned : HTTP/1.1 201 Created Date: Fri, 11 Sep 2009 13:36:47 GMT Server: Microsoft-IIS/6.0 X-Powered-By: ASP.NET X-AspNet-Version: 2.0.50727 DataServiceVersion: 1.0; Location: http://andreiri/MyProject.Data/Data.svc/Zone(75) Cache-Control: no-cache Content-Type: application/atom+xml;charset=utf-8 Content-Length: 2213 <?xml version="1.0" encoding="utf-8" standalone="yes"?> <entry xml:base="http://andreiri/MyProject.Data/Data.svc/" xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices" xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata" xmlns="http://www.w3.org/2005/Atom"> <id>http://andreiri/MyProject.Data/Data.svc/Zone(75)</id> <title type="text"></title> <updated>2009-09-11T13:36:47Z</updated> <author> <name /> </author> <link rel="edit" title="Zone" href="Zone(75)" /> <link rel="http://schemas.microsoft.com/ado/2007/08/dataservices/related/CenterZone" type="application/atom+xml;type=feed" title="CenterZone" href="Zone(75)/CenterZone" /> <link rel="http://schemas.microsoft.com/ado/2007/08/dataservices/related/ZoneMobil" type="application/atom+xml;type=feed" title="ZoneMobil" href="Zone(75)/ZoneMobil" /> <link rel="http://schemas.microsoft.com/ado/2007/08/dataservices/related/StareZone" type="application/atom+xml;type=entry" title="StareZone" href="Zone(75)/StareZone" /> <link rel="http://schemas.microsoft.com/ado/2007/08/dataservices/related/TipZone" type="application/atom+xml;type=entry" title="TipZone" href="Zone(75)/TipZone" /> <link rel="http://schemas.microsoft.com/ado/2007/08/dataservices/related/User" type="application/atom+xml;type=entry" title="User" href="Zone(75)/User" /> <category term="MyProject123Model.Zone" scheme="http://schemas.microsoft.com ado/2007/08/dataservices/scheme" /> <content type="application/xml"> <m:properties> <d:IdZone m:type="Edm.Int32">75</d:IdZone> <d:X_Post m:type="Edm.Decimal">587647.4705</d:X_Post> <d:Y_Post m:type="Edm.Decimal">325783.077599999</d:Y_Post> <d:X_Repost m:type="Edm.Decimal" m:null="true" /> <d:Y_Repost m:type="Edm.Decimal" m:null="true" /> <d:Data m:type="Edm.DateTime">2009-09-11T16:36:40.588951+03:00</d:Data> <d:Detalii>aslkdfjasldkfj</d:Detalii> <d:IdElement m:type="Edm.Int32">1</d:IdElement> </m:properties> </content> </entry> Why do I get an exception? And, using this in a clean project does not throw the exception..

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  • NerdDinner routing

    - by Joe
    I watched Scot hanselmann's presentation at mix '10. When he presented the tiny urls for Nerddinner he said it was a 2 part process. a) modify global.asax.cs with a new route b)some sort of isapi rewrite. When I implemented this in my asp.net mvc 2 site I only did part a. and it works. why then did he do part b?? what is the advantages of doing that???

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  • availability of Win32_MountPoint and Win32_Volume on Windows XP?

    - by SteveC
    From the MSDN articles I've found -- http://msdn.microsoft.com/en-us/library/aa394515(v=VS.85).aspx -- Win32_Volume and Win32_MountPoint aren't available on Windows XP. However, I'm developing a C# app on Windows XP (64bit), and I can get to those WMI classes just fine. Users of my app will be on Windows XP sp2 with .Net 3.5 sp1. Googling around, I can't determine whether I can count on this or not. Am I successful on my system because of one or more of the following: - windows xp service pack 2? - visual studio 2008 sp1 was installed? - .Net 3.5 sp1? Should I use something other than WMI to get at the volume/mountpoint info? Below is sample code that's working... public static Dictionary<string, NameValueCollection> GetAllVolumeDeviceIDs() { Dictionary<string, NameValueCollection> ret = new Dictionary<string, NameValueCollection>(); // retrieve information from Win32_Volume try { using (ManagementClass volClass = new ManagementClass("Win32_Volume")) { using (ManagementObjectCollection mocVols = volClass.GetInstances()) { // iterate over every volume foreach (ManagementObject moVol in mocVols) { // get the volume's device ID (will be key into our dictionary) string devId = moVol.GetPropertyValue("DeviceID").ToString(); ret.Add(devId, new NameValueCollection()); //Console.WriteLine("Vol: {0}", devId); // for each non-null property on the Volume, add it to our NameValueCollection foreach (PropertyData p in moVol.Properties) { if (p.Value == null) continue; ret[devId].Add(p.Name, p.Value.ToString()); //Console.WriteLine("\t{0}: {1}", p.Name, p.Value); } // find the mountpoints of this volume using (ManagementObjectCollection mocMPs = moVol.GetRelationships("Win32_MountPoint")) { foreach (ManagementObject moMP in mocMPs) { // only care about adding directory // Directory prop will be something like "Win32_Directory.Name=\"C:\\\\\"" string dir = moMP["Directory"].ToString(); // find opening/closing quotes in order to get the substring we want int first = dir.IndexOf('"') + 1; int last = dir.LastIndexOf('"'); string dirSubstr = dir.Substring(first , last - first); // use GetFullPath to normalize/unescape any extra backslashes string fullpath = Path.GetFullPath(dirSubstr); ret[devId].Add(MOUNTPOINT_DIRS_KEY, fullpath); } } } } } } catch (Exception ex) { Console.WriteLine("Problem retrieving Volume information from WMI. {0} - \n{1}",ex.Message,ex.StackTrace); return ret; } return ret; }

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  • Limit WebClient DownloadFile maximum file size

    - by Jack Juiceson
    Hi everyone, In my asp .net project, my main page receives URL as a parameter I need to download internally and then process it. I know that I can use WebClient's DownloadFile method however I want to avoid malicious user from giving a url to a huge file, which will unnecessary traffic from my server. In order to avoid this, I'm looking for a solution to set maximum file size that DownloadFile will download. Thank you in advance, Jack

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  • Handling Errors from HttpWebRequest.GetResponse

    - by Jason
    Hey experts - I'm having a ridiculous time trying to get an SMS API working (ZeepMobile, if you're interested) with .NET... I've been around .NET for a few years, but with all this social networking and API stuff, I need to get into the HttpWebRequest a bit. I'm new at it, but not completely new; I was able to hook up my site to Twitter without too much fuss (ie, I was able to modify someone's code to work for me). Anyways, the way their API works is to send an SMS message, you send them a POST and they respond back to you. I can send it just fine, but every time I do, rather than echo back something helpful to figure out what the error is, I get the Yellow Error Page Of Death (YEPOD) saying something to the effect of "The remote server returned an error: (400) Bad Request." This occurs on my line: '...creation of httpwebrequest here...' Dim myWebResponse As WebResponse myWebResponse = request.GetResponse() '<--- error line Is there any way to simply receive the error from the server rather than have the webserver throw an exception and give me the YEPOD? Or better yet, can anyone post a working example of their Zeep code? :) Thanks! EDIT: Here's my whole code block: Public Shared Function SendTextMessage(ByVal username As String, _ ByVal txt As String) As String Dim content As String = "user_id=" + _ username + "&body=" + Current.Server.UrlEncode(txt) Dim httpDate As String = DateTime.Now.ToString("r") Dim canonicalString As String = API_KEY & httpDate & content Dim encoding As New System.Text.UTF8Encoding Dim hmacSha As New HMACSHA1(encoding.GetBytes(SECRET_ACCESS_KEY)) Dim hash() As Byte = hmacSha.ComputeHash(encoding.GetBytes(canonicalString)) Dim b64 As String = Convert.ToBase64String(hash) 'connect with zeep' Dim request As HttpWebRequest = CType(WebRequest.Create(_ "https://api.zeepmobile.com/messaging/2008-07-14/send_message"), HttpWebRequest) request.Method = "POST" request.ServicePoint.Expect100Continue = False ' set the authorization levels' request.Headers.Add("Authorization", "Zeep " & API_KEY & ":" & b64) request.ContentType = "application/x-www-form-urlencoded" request.ContentLength = content.Length ' set up and write to stream' Dim reqStream As New StreamWriter(request.GetRequestStream()) reqStream.Write(content) reqStream.Close() Dim msg As String = "" msg = reqStream.ToString Dim myWebResponse As WebResponse Dim myResponseStream As Stream Dim myStreamReader As StreamReader myWebResponse = request.GetResponse() myResponseStream = myWebResponse.GetResponseStream() myStreamReader = New StreamReader(myResponseStream) msg = myStreamReader.ReadToEnd() myStreamReader.Close() myResponseStream.Close() ' Close the WebResponse' myWebResponse.Close() Return msg End Function

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  • Reverse function of HttpUtility.ParseQueryString

    - by Palani
    .Net System.Web.HttpUtility class has following function to parse query string into NameValueCollection. public static NameValueCollection ParseQueryString(string query); MSDN: http://msdn.microsoft.com/en-us/library/ms150046.aspx Is there any function to do reverse , convert NameValueCollection into Query String.

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  • Throwing exception vs checking null, for a null argument

    - by dotnetdev
    What factors dictate throwing an exception if argument is null (eg if (a is null) throw new ArgumentNullException() ), as opposed to checking the argument if it is null beforehand. I don't see why the exception should be thrown rather than checking for null in the first place? What benefit is there in the throw exception approach? This is for C#/.NET Thanks

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