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  • Is MarshalByRefObject special?

    - by Vilx-
    .NET has a thing called remoting where you can pass objects around between separate appdomains or even physical machines. I don't fully understand how the magic is done, hence this question. In remoting there are two base ways of passing objects around - either they can be serialized (converted to a bunch of bytes and the rebuilt at the other end) or they can inherit from MarshalByRefObject, in which case .NET makes some transparent proxies and all method calls are forwarded back to the original instance. This is pretty cool and works like magic. And I don't like magic in programming. Looking at the MarshalByRefObject with the Reflector I don't see anything that would set it apart from any other typical object. Not even a weird internal attribute or anything. So how is the whole transparent proxy thing organized? Can I make such a mechanism myself? Can I make an alternate MyMarshalByRefObject which would not inherit from MarshalByRefObject but would still act the same? Or is MarshalByRefObject receiving some special treatment by the .NET engine itself and the whole remoting feat is non-duplicatable by mere mortals?

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  • Use the [Serializable] attribute or subclassing from MarshalByRefObject?

    - by Theo Lenndorff
    I'd like to use an object across AppDomains. For this I can use the [Serializeable] attribute: [Serializable] class MyClass { public string GetSomeString() { return "someString" } } Or subclass from MarshalByRefObject: class MyClass: MarshalByRefObject { public string GetSomeString() { return "someString" } } In both cases I can use the class like this: AppDomain appDomain = AppDomain.CreateDomain("AppDomain"); MyClass myObject = (MyClass)appDomain.CreateInstanceAndUnwrap( typeof(MyClass).Assembly.FullName, typeof(MyClass).FullName); Console.WriteLine(myObject.GetSomeString()); Why do both approaches seem to have the same effect? What is the difference in both approaches? When should I favor the one approach over the other? EDIT: At the surface I know that there are differences between both mechanisms, but if someone jumped out of a bush and asked me the question I couldn't give him a proper answer. The questions are quite open questions. I hoped that someone can explain it better than I could do.

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  • How do I pass references as method parameters across AppDomains?

    - by Thiado de Arruda
    I have been trying to get the following code to work(everything is defined in the same assembly) : namespace SomeApp{ public class A : MarshalByRefObject { public byte[] GetSomeData() { // } } public class B : MarshalByRefObject { private A remoteObj; public void SetA(A remoteObj) { this.remoteObj = remoteObj; } } public class C { A someA = new A(); public void Init() { AppDomain domain = AppDomain.CreateDomain("ChildDomain"); string currentAssemblyPath = Assembly.GetExecutingAssembly().Location; B remoteB = domain.domain.CreateInstanceFromAndUnwrap(currentAssemblyPath,"SomeApp.B") as B; remoteB.SetA(someA); // this throws an ArgumentException "Object type cannot be converted to target type." } } } What I'm trying to do is pass a reference of an 'A' instance created in the first AppDomain to the child domain and have the child domain execute a method on the first domain. In some point on 'B' code I'm going to call 'remoteObj.GetSomeData()'. This has to be done because the 'byte[]' from 'GetSomeData' method must be 'calculated' on the first appdomain. What should I do to avoid the exception, or what can I do to achieve the same result?

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  • How can I find out if an instance is a MarshalByRef proxy?

    - by Will
    I know there's a way, I know I've done it (a long time) before, but I can't remember or find out how to do it!!! var otherDomain = AppDomain.Create("Lol my memory sucks"); var myRemotableType = typeof(MyTypeThatExtendsMBRO); var proxy = otherDomain .CreateInstanceAndUnwrap( type.Assembly.FullName, type.FullName); // how do you do this next step??? bool isProxy = IsYouIsOrIsYouAintAProxy(proxy);

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  • Why can't pass Marshaled interface as integer(or pointer)

    - by cemick
    I passed ref of interface from Visio Add-ins to MyCOMServer (http://stackoverflow.com/questions/2455183/interface-marshalling-in-delphi).I have to pass interface as pointer in internals method of MyCOMServer. I try to pass interface to internal method as pointer of interface, but after back cast when i try call method of interface I get exception. Simple example(Fisrt block execute without error, but At Second block I get Exception after addressed to property of IVApplication interface): procedure TMyCOMServer.test(const Interface_:IDispatch); stdcall; var IMy:_IMyInterface; V: Variant; Str: String; I: integer; Vis: IVApplication; begin ...... Self.QuaryInterface(_IMyInterface,IMy); str := IA.ApplicationName; V := Integer(IMy); i := V; Pointer(IMy) := Pointer(i); str := IMy.SomeProperty; // normal completion str := (Interface_ as IVApplication).Path; V := Interface_; I := V; Pointer(Vis) := Pointer(i); str := Vis.Path; // 'access violation at 0x76358e29: read of address 0xfeeefeee' end; Why I can't do like this?

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  • C# How to output to GUI when data is coming via an interface via MarshalByRefObject?

    - by Tom
    Hey, can someone please show me how i can write the output of OnCreateFile to a GUI? I thought the GUI would have to be declared at the bottom in the main function, so how do i then refer to it within OnCreateFile? using System; using System.Collections.Generic; using System.Runtime.Remoting; using System.Text; using System.Diagnostics; using System.IO; using EasyHook; using System.Drawing; using System.Windows.Forms; namespace FileMon { public class FileMonInterface : MarshalByRefObject { public void IsInstalled(Int32 InClientPID) { //Console.WriteLine("FileMon has been installed in target {0}.\r\n", InClientPID); } public void OnCreateFile(Int32 InClientPID, String[] InFileNames) { for (int i = 0; i < InFileNames.Length; i++) { String[] s = InFileNames[i].ToString().Split('\t'); if (s[0].ToString().Contains("ROpen")) { //Console.WriteLine(DateTime.Now.Hour+":"+DateTime.Now.Minute+":"+DateTime.Now.Second+"."+DateTime.Now.Millisecond + "\t" + s[0] + "\t" + getProcessName(int.Parse(s[1])) + "\t" + getRootHive(s[2])); Program.ff.enterText(DateTime.Now.Hour + ":" + DateTime.Now.Minute + ":" + DateTime.Now.Second + "." + DateTime.Now.Millisecond + "\t" + s[0] + "\t" + getProcessName(int.Parse(s[1])) + "\t" + getRootHive(s[2])); } else if (s[0].ToString().Contains("RQuery")) { Console.WriteLine(DateTime.Now.Hour + ":" + DateTime.Now.Minute + ":" + DateTime.Now.Second + "." + DateTime.Now.Millisecond + "\t" + s[0] + "\t" + getProcessName(int.Parse(s[1])) + "\t" + getRootHive(s[2])); } else if (s[0].ToString().Contains("RDelete")) { Console.WriteLine(DateTime.Now.Hour + ":" + DateTime.Now.Minute + ":" + DateTime.Now.Second + "." + DateTime.Now.Millisecond + "\t" + s[0] + "\t" + getProcessName(int.Parse(s[0])) + "\t" + getRootHive(s[1])); } else if (s[0].ToString().Contains("FCreate")) { //Console.WriteLine(DateTime.Now.Hour+":"+DateTime.Now.Minute+":"+DateTime.Now.Second+"."+DateTime.Now.Millisecond + "\t" + s[0] + "\t" + getProcessName(int.Parse(s[1])) + "\t" + s[2]); } } } public void ReportException(Exception InInfo) { Console.WriteLine("The target process has reported an error:\r\n" + InInfo.ToString()); } public void Ping() { } public String getProcessName(int ID) { String name = ""; Process[] process = Process.GetProcesses(); for (int i = 0; i < process.Length; i++) { if (process[i].Id == ID) { name = process[i].ProcessName; } } return name; } public String getRootHive(String hKey) { int r = hKey.CompareTo("2147483648"); int r1 = hKey.CompareTo("2147483649"); int r2 = hKey.CompareTo("2147483650"); int r3 = hKey.CompareTo("2147483651"); int r4 = hKey.CompareTo("2147483653"); if (r == 0) { return "HKEY_CLASSES_ROOT"; } else if (r1 == 0) { return "HKEY_CURRENT_USER"; } else if (r2 == 0) { return "HKEY_LOCAL_MACHINE"; } else if (r3 == 0) { return "HKEY_USERS"; } else if (r4 == 0) { return "HKEY_CURRENT_CONFIG"; } else return hKey.ToString(); } } class Program : System.Windows.Forms.Form { static String ChannelName = null; public static Form1 ff; Program() // ADD THIS CONSTRUCTOR { InitializeComponent(); } static void Main() { try { Config.Register("A FileMon like demo application.", "FileMon.exe", "FileMonInject.dll"); RemoteHooking.IpcCreateServer<FileMonInterface>(ref ChannelName, WellKnownObjectMode.SingleCall); Process[] p = Process.GetProcesses(); for (int i = 0; i < p.Length; i++) { try { RemoteHooking.Inject(p[i].Id, "FileMonInject.dll", "FileMonInject.dll", ChannelName); } catch (Exception e) { } } } catch (Exception ExtInfo) { Console.WriteLine("There was an error while connecting to target:\r\n{0}", ExtInfo.ToString()); } } } }

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  • Creating a Sandboxed Instance

    - by Ricardo Peres
    In .NET 4.0 the policy APIs have changed a bit. Here's how you can create a sandboxed instance of a type, which must inherit from MarshalByRefObject: static T CreateRestrictedType<T>(SecurityZone zone, params Assembly [] fullTrustAssemblies) where T : MarshalByRefObject, new() { return(CreateRestrictedType<T>(zone, fullTrustAssemblies, new IPermission [0]); } static T CreateRestrictedType<T>(SecurityZone zone, params IPermission [] additionalPermissions) where T : MarshalByRefObject, new() { return(CreateRestrictedType<T>(zone, new Assembly [0], additionalPermissions); } static T CreateRestrictedType<T>(SecurityZone zone, Assembly [] fullTrustAssemblies, IPermission [] additionalPermissions) where T : MarshalByRefObject, new() { Evidence evidence = new Evidence(); evidence.AddHostEvidence(new Zone(zone)); PermissionSet evidencePermissionSet = SecurityManager.GetStandardSandbox(evidence); foreach (IPermission permission in additionalPermissions ?? new IPermission[ 0 ]) { evidencePermissionSet.AddPermission(permission); } StrongName [] strongNames = (fullTrustAssemblies ?? new Assembly[0]).Select(a = a.Evidence.GetHostEvidence<StrongName>()).ToArray(); AppDomainSetup adSetup = new AppDomainSetup(); adSetup.ApplicationBase = Path.GetDirectoryName(typeof(T).Assembly.Location); AppDomain newDomain = AppDomain.CreateDomain("Sandbox", evidence, adSetup, evidencePermissionSet, strongNames); ObjectHandle handle = Activator.CreateInstanceFrom(newDomain, typeof(T).Assembly.ManifestModule.FullyQualifiedName, typeof(T).FullName); return (handle.Unwrap() as T); } SyntaxHighlighter.config.clipboardSwf = 'http://alexgorbatchev.com/pub/sh/2.0.320/scripts/clipboard.swf'; SyntaxHighlighter.brushes.CSharp.aliases = ['c#', 'c-sharp', 'csharp']; SyntaxHighlighter.all();

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  • Hosting the Razor Engine for Templating in Non-Web Applications

    - by Rick Strahl
    Microsoft’s new Razor HTML Rendering Engine that is currently shipping with ASP.NET MVC previews can be used outside of ASP.NET. Razor is an alternative view engine that can be used instead of the ASP.NET Page engine that currently works with ASP.NET WebForms and MVC. It provides a simpler and more readable markup syntax and is much more light weight in terms of functionality than the full blown WebForms Page engine, focusing only on features that are more along the lines of a pure view engine (or classic ASP!) with focus on expression and code rendering rather than a complex control/object model. Like the Page engine though, the parser understands .NET code syntax which can be embedded into templates, and behind the scenes the engine compiles markup and script code into an executing piece of .NET code in an assembly. Although it ships as part of the ASP.NET MVC and WebMatrix the Razor Engine itself is not directly dependent on ASP.NET or IIS or HTTP in any way. And although there are some markup and rendering features that are optimized for HTML based output generation, Razor is essentially a free standing template engine. And what’s really nice is that unlike the ASP.NET Runtime, Razor is fairly easy to host inside of your own non-Web applications to provide templating functionality. Templating in non-Web Applications? Yes please! So why might you host a template engine in your non-Web application? Template rendering is useful in many places and I have a number of applications that make heavy use of it. One of my applications – West Wind Html Help Builder - exclusively uses template based rendering to merge user supplied help text content into customizable and executable HTML markup templates that provide HTML output for CHM style HTML Help. This is an older product and it’s not actually using .NET at the moment – and this is one reason I’m looking at Razor for script hosting at the moment. For a few .NET applications though I’ve actually used the ASP.NET Runtime hosting to provide templating and mail merge style functionality and while that works reasonably well it’s a very heavy handed approach. It’s very resource intensive and has potential issues with versioning in various different versions of .NET. The generic implementation I created in the article above requires a lot of fix up to mimic an HTTP request in a non-HTTP environment and there are a lot of little things that have to happen to ensure that the ASP.NET runtime works properly most of it having nothing to do with the templating aspect but just satisfying ASP.NET’s requirements. The Razor Engine on the other hand is fairly light weight and completely decoupled from the ASP.NET runtime and the HTTP processing. Rather it’s a pure template engine whose sole purpose is to render text templates. Hosting this engine in your own applications can be accomplished with a reasonable amount of code (actually just a few lines with the tools I’m about to describe) and without having to fake HTTP requests. It’s also much lighter on resource usage and you can easily attach custom properties to your base template implementation to easily pass context from the parent application into templates all of which was rather complicated with ASP.NET runtime hosting. Installing the Razor Template Engine You can get Razor as part of the MVC 3 (RC and later) or Web Matrix. Both are available as downloadable components from the Web Platform Installer Version 3.0 (!important – V2 doesn’t show these components). If you already have that version of the WPI installed just fire it up. You can get the latest version of the Web Platform Installer from here: http://www.microsoft.com/web/gallery/install.aspx Once the platform Installer 3.0 is installed install either MVC 3 or ASP.NET Web Pages. Once installed you’ll find a System.Web.Razor assembly in C:\Program Files\Microsoft ASP.NET\ASP.NET Web Pages\v1.0\Assemblies\System.Web.Razor.dll which you can add as a reference to your project. Creating a Wrapper The basic Razor Hosting API is pretty simple and you can host Razor with a (large-ish) handful of lines of code. I’ll show the basics of it later in this article. However, if you want to customize the rendering and handle assembly and namespace includes for the markup as well as deal with text and file inputs as well as forcing Razor to run in a separate AppDomain so you can unload the code-generated assemblies and deal with assembly caching for re-used templates little more work is required to create something that is more easily reusable. For this reason I created a Razor Hosting wrapper project that combines a bunch of this functionality into an easy to use hosting class, a hosting factory that can load the engine in a separate AppDomain and a couple of hosting containers that provided folder based and string based caching for templates for an easily embeddable and reusable engine with easy to use syntax. If you just want the code and play with the samples and source go grab the latest code from the Subversion Repository at: http://www.west-wind.com:8080/svn/articles/trunk/RazorHosting/ or a snapshot from: http://www.west-wind.com/files/tools/RazorHosting.zip Getting Started Before I get into how hosting with Razor works, let’s take a look at how you can get up and running quickly with the wrapper classes provided. It only takes a few lines of code. The easiest way to use these Razor Hosting Wrappers is to use one of the two HostContainers provided. One is for hosting Razor scripts in a directory and rendering them as relative paths from these script files on disk. The other HostContainer serves razor scripts from string templates… Let’s start with a very simple template that displays some simple expressions, some code blocks and demonstrates rendering some data from contextual data that you pass to the template in the form of a ‘context’. Here’s a simple Razor template: @using System.Reflection Hello @Context.FirstName! Your entry was entered on: @Context.Entered @{ // Code block: Update the host Windows Form passed in through the context Context.WinForm.Text = "Hello World from Razor at " + DateTime.Now.ToString(); } AppDomain Id: @AppDomain.CurrentDomain.FriendlyName Assembly: @Assembly.GetExecutingAssembly().FullName Code based output: @{ // Write output with Response object from code string output = string.Empty; for (int i = 0; i < 10; i++) { output += i.ToString() + " "; } Response.Write(output); } Pretty easy to see what’s going on here. The only unusual thing in this code is the Context object which is an arbitrary object I’m passing from the host to the template by way of the template base class. I’m also displaying the current AppDomain and the executing Assembly name so you can see how compiling and running a template actually loads up new assemblies. Also note that as part of my context I’m passing a reference to the current Windows Form down to the template and changing the title from within the script. It’s a silly example, but it demonstrates two-way communication between host and template and back which can be very powerful. The easiest way to quickly render this template is to use the RazorEngine<TTemplateBase> class. The generic parameter specifies a template base class type that is used by Razor internally to generate the class it generates from a template. The default implementation provided in my RazorHosting wrapper is RazorTemplateBase. Here’s a simple one that renders from a string and outputs a string: var engine = new RazorEngine<RazorTemplateBase>(); // we can pass any object as context - here create a custom context var context = new CustomContext() { WinForm = this, FirstName = "Rick", Entered = DateTime.Now.AddDays(-10) }; string output = engine.RenderTemplate(this.txtSource.Text new string[] { "System.Windows.Forms.dll" }, context); if (output == null) this.txtResult.Text = "*** ERROR:\r\n" + engine.ErrorMessage; else this.txtResult.Text = output; Simple enough. This code renders a template from a string input and returns a result back as a string. It  creates a custom context and passes that to the template which can then access the Context’s properties. Note that anything passed as ‘context’ must be serializable (or MarshalByRefObject) – otherwise you get an exception when passing the reference over AppDomain boundaries (discussed later). Passing a context is optional, but is a key feature in being able to share data between the host application and the template. Note that we use the Context object to access FirstName, Entered and even the host Windows Form object which is used in the template to change the Window caption from within the script! In the code above all the work happens in the RenderTemplate method which provide a variety of overloads to read and write to and from strings, files and TextReaders/Writers. Here’s another example that renders from a file input using a TextReader: using (reader = new StreamReader("templates\\simple.csHtml", true)) { result = host.RenderTemplate(reader, new string[] { "System.Windows.Forms.dll" }, this.CustomContext); } RenderTemplate() is fairly high level and it handles loading of the runtime, compiling into an assembly and rendering of the template. If you want more control you can use the lower level methods to control each step of the way which is important for the HostContainers I’ll discuss later. Basically for those scenarios you want to separate out loading of the engine, compiling into an assembly and then rendering the template from the assembly. Why? So we can keep assemblies cached. In the code above a new assembly is created for each template rendered which is inefficient and uses up resources. Depending on the size of your templates and how often you fire them you can chew through memory very quickly. This slighter lower level approach is only a couple of extra steps: // we can pass any object as context - here create a custom context var context = new CustomContext() { WinForm = this, FirstName = "Rick", Entered = DateTime.Now.AddDays(-10) }; var engine = new RazorEngine<RazorTemplateBase>(); string assId = null; using (StringReader reader = new StringReader(this.txtSource.Text)) { assId = engine.ParseAndCompileTemplate(new string[] { "System.Windows.Forms.dll" }, reader); } string output = engine.RenderTemplateFromAssembly(assId, context); if (output == null) this.txtResult.Text = "*** ERROR:\r\n" + engine.ErrorMessage; else this.txtResult.Text = output; The difference here is that you can capture the assembly – or rather an Id to it – and potentially hold on to it to render again later assuming the template hasn’t changed. The HostContainers take advantage of this feature to cache the assemblies based on certain criteria like a filename and file time step or a string hash that if not change indicate that an assembly can be reused. Note that ParseAndCompileTemplate returns an assembly Id rather than the assembly itself. This is done so that that the assembly always stays in the host’s AppDomain and is not passed across AppDomain boundaries which would cause load failures. We’ll talk more about this in a minute but for now just realize that assemblies references are stored in a list and are accessible by this ID to allow locating and re-executing of the assembly based on that id. Reuse of the assembly avoids recompilation overhead and creation of yet another assembly that loads into the current AppDomain. You can play around with several different versions of the above code in the main sample form:   Using Hosting Containers for more Control and Caching The above examples simply render templates into assemblies each and every time they are executed. While this works and is even reasonably fast, it’s not terribly efficient. If you render templates more than once it would be nice if you could cache the generated assemblies for example to avoid re-compiling and creating of a new assembly each time. Additionally it would be nice to load template assemblies into a separate AppDomain optionally to be able to be able to unload assembli es and also to protect your host application from scripting attacks with malicious template code. Hosting containers provide also provide a wrapper around the RazorEngine<T> instance, a factory (which allows creation in separate AppDomains) and an easy way to start and stop the container ‘runtime’. The Razor Hosting samples provide two hosting containers: RazorFolderHostContainer and StringHostContainer. The folder host provides a simple runtime environment for a folder structure similar in the way that the ASP.NET runtime handles a virtual directory as it’s ‘application' root. Templates are loaded from disk in relative paths and the resulting assemblies are cached unless the template on disk is changed. The string host also caches templates based on string hashes – if the same string is passed a second time a cached version of the assembly is used. Here’s how HostContainers work. I’ll use the FolderHostContainer because it’s likely the most common way you’d use templates – from disk based templates that can be easily edited and maintained on disk. The first step is to create an instance of it and keep it around somewhere (in the example it’s attached as a property to the Form): RazorFolderHostContainer Host = new RazorFolderHostContainer(); public RazorFolderHostForm() { InitializeComponent(); // The base path for templates - templates are rendered with relative paths // based on this path. Host.TemplatePath = Path.Combine(Environment.CurrentDirectory, TemplateBaseFolder); // Add any assemblies you want reference in your templates Host.ReferencedAssemblies.Add("System.Windows.Forms.dll"); // Start up the host container Host.Start(); } Next anytime you want to render a template you can use simple code like this: private void RenderTemplate(string fileName) { // Pass the template path via the Context var relativePath = Utilities.GetRelativePath(fileName, Host.TemplatePath); if (!Host.RenderTemplate(relativePath, this.Context, Host.RenderingOutputFile)) { MessageBox.Show("Error: " + Host.ErrorMessage); return; } this.webBrowser1.Navigate("file://" + Host.RenderingOutputFile); } You can also render the output to a string instead of to a file: string result = Host.RenderTemplateToString(relativePath,context); Finally if you want to release the engine and shut down the hosting AppDomain you can simply do: Host.Stop(); Stopping the AppDomain and restarting it (ie. calling Stop(); followed by Start()) is also a nice way to release all resources in the AppDomain. The FolderBased domain also supports partial Rendering based on root path based relative paths with the same caching characteristics as the main templates. From within a template you can call out to a partial like this: @RenderPartial(@"partials\PartialRendering.cshtml", Context) where partials\PartialRendering.cshtml is a relative to the template root folder. The folder host example lets you load up templates from disk and display the result in a Web Browser control which demonstrates using Razor HTML output from templates that contain HTML syntax which happens to me my target scenario for Html Help Builder.   The Razor Engine Wrapper Project The project I created to wrap Razor hosting has a fair bit of code and a number of classes associated with it. Most of the components are internally used and as you can see using the final RazorEngine<T> and HostContainer classes is pretty easy. The classes are extensible and I suspect developers will want to build more customized host containers for their applications. Host containers are the key to wrapping up all functionality – Engine, BaseTemplate, AppDomain Hosting, Caching etc in a logical piece that is ready to be plugged into an application. When looking at the code there are a couple of core features provided: Core Razor Engine Hosting This is the core Razor hosting which provides the basics of loading a template, compiling it into an assembly and executing it. This is fairly straightforward, but without a host container that can cache assemblies based on some criteria templates are recompiled and re-created each time which is inefficient (although pretty fast). The base engine wrapper implementation also supports hosting the Razor runtime in a separate AppDomain for security and the ability to unload it on demand. Host Containers The engine hosting itself doesn’t provide any sort of ‘runtime’ service like picking up files from disk, caching assemblies and so forth. So my implementation provides two HostContainers: RazorFolderHostContainer and RazorStringHostContainer. The FolderHost works off a base directory and loads templates based on relative paths (sort of like the ASP.NET runtime does off a virtual). The HostContainers also deal with caching of template assemblies – for the folder host the file date is tracked and checked for updates and unless the template is changed a cached assembly is reused. The StringHostContainer similiarily checks string hashes to figure out whether a particular string template was previously compiled and executed. The HostContainers also act as a simple startup environment and a single reference to easily store and reuse in an application. TemplateBase Classes The template base classes are the base classes that from which the Razor engine generates .NET code. A template is parsed into a class with an Execute() method and the class is based on this template type you can specify. RazorEngine<TBaseTemplate> can receive this type and the HostContainers default to specific templates in their base implementations. Template classes are customizable to allow you to create templates that provide application specific features and interaction from the template to your host application. How does the RazorEngine wrapper work? You can browse the source code in the links above or in the repository or download the source, but I’ll highlight some key features here. Here’s part of the RazorEngine implementation that can be used to host the runtime and that demonstrates the key code required to host the Razor runtime. The RazorEngine class is implemented as a generic class to reflect the Template base class type: public class RazorEngine<TBaseTemplateType> : MarshalByRefObject where TBaseTemplateType : RazorTemplateBase The generic type is used to internally provide easier access to the template type and assignments on it as part of the template processing. The class also inherits MarshalByRefObject to allow execution over AppDomain boundaries – something that all the classes discussed here need to do since there is much interaction between the host and the template. The first two key methods deal with creating a template assembly: /// <summary> /// Creates an instance of the RazorHost with various options applied. /// Applies basic namespace imports and the name of the class to generate /// </summary> /// <param name="generatedNamespace"></param> /// <param name="generatedClass"></param> /// <returns></returns> protected RazorTemplateEngine CreateHost(string generatedNamespace, string generatedClass) { Type baseClassType = typeof(TBaseTemplateType); RazorEngineHost host = new RazorEngineHost(new CSharpRazorCodeLanguage()); host.DefaultBaseClass = baseClassType.FullName; host.DefaultClassName = generatedClass; host.DefaultNamespace = generatedNamespace; host.NamespaceImports.Add("System"); host.NamespaceImports.Add("System.Text"); host.NamespaceImports.Add("System.Collections.Generic"); host.NamespaceImports.Add("System.Linq"); host.NamespaceImports.Add("System.IO"); return new RazorTemplateEngine(host); } /// <summary> /// Parses and compiles a markup template into an assembly and returns /// an assembly name. The name is an ID that can be passed to /// ExecuteTemplateByAssembly which picks up a cached instance of the /// loaded assembly. /// /// </summary> /// <param name="namespaceOfGeneratedClass">The namespace of the class to generate from the template</param> /// <param name="generatedClassName">The name of the class to generate from the template</param> /// <param name="ReferencedAssemblies">Any referenced assemblies by dll name only. Assemblies must be in execution path of host or in GAC.</param> /// <param name="templateSourceReader">Textreader that loads the template</param> /// <remarks> /// The actual assembly isn't returned here to allow for cross-AppDomain /// operation. If the assembly was returned it would fail for cross-AppDomain /// calls. /// </remarks> /// <returns>An assembly Id. The Assembly is cached in memory and can be used with RenderFromAssembly.</returns> public string ParseAndCompileTemplate( string namespaceOfGeneratedClass, string generatedClassName, string[] ReferencedAssemblies, TextReader templateSourceReader) { RazorTemplateEngine engine = CreateHost(namespaceOfGeneratedClass, generatedClassName); // Generate the template class as CodeDom GeneratorResults razorResults = engine.GenerateCode(templateSourceReader); // Create code from the codeDom and compile CSharpCodeProvider codeProvider = new CSharpCodeProvider(); CodeGeneratorOptions options = new CodeGeneratorOptions(); // Capture Code Generated as a string for error info // and debugging LastGeneratedCode = null; using (StringWriter writer = new StringWriter()) { codeProvider.GenerateCodeFromCompileUnit(razorResults.GeneratedCode, writer, options); LastGeneratedCode = writer.ToString(); } CompilerParameters compilerParameters = new CompilerParameters(ReferencedAssemblies); // Standard Assembly References compilerParameters.ReferencedAssemblies.Add("System.dll"); compilerParameters.ReferencedAssemblies.Add("System.Core.dll"); compilerParameters.ReferencedAssemblies.Add("Microsoft.CSharp.dll"); // dynamic support! // Also add the current assembly so RazorTemplateBase is available compilerParameters.ReferencedAssemblies.Add(Assembly.GetExecutingAssembly().CodeBase.Substring(8)); compilerParameters.GenerateInMemory = Configuration.CompileToMemory; if (!Configuration.CompileToMemory) compilerParameters.OutputAssembly = Path.Combine(Configuration.TempAssemblyPath, "_" + Guid.NewGuid().ToString("n") + ".dll"); CompilerResults compilerResults = codeProvider.CompileAssemblyFromDom(compilerParameters, razorResults.GeneratedCode); if (compilerResults.Errors.Count > 0) { var compileErrors = new StringBuilder(); foreach (System.CodeDom.Compiler.CompilerError compileError in compilerResults.Errors) compileErrors.Append(String.Format(Resources.LineX0TColX1TErrorX2RN, compileError.Line, compileError.Column, compileError.ErrorText)); this.SetError(compileErrors.ToString() + "\r\n" + LastGeneratedCode); return null; } AssemblyCache.Add(compilerResults.CompiledAssembly.FullName, compilerResults.CompiledAssembly); return compilerResults.CompiledAssembly.FullName; } Think of the internal CreateHost() method as setting up the assembly generated from each template. Each template compiles into a separate assembly. It sets up namespaces, and assembly references, the base class used and the name and namespace for the generated class. ParseAndCompileTemplate() then calls the CreateHost() method to receive the template engine generator which effectively generates a CodeDom from the template – the template is turned into .NET code. The code generated from our earlier example looks something like this: //------------------------------------------------------------------------------ // <auto-generated> // This code was generated by a tool. // Runtime Version:4.0.30319.1 // // Changes to this file may cause incorrect behavior and will be lost if // the code is regenerated. // </auto-generated> //------------------------------------------------------------------------------ namespace RazorTest { using System; using System.Text; using System.Collections.Generic; using System.Linq; using System.IO; using System.Reflection; public class RazorTemplate : RazorHosting.RazorTemplateBase { #line hidden public RazorTemplate() { } public override void Execute() { WriteLiteral("Hello "); Write(Context.FirstName); WriteLiteral("! Your entry was entered on: "); Write(Context.Entered); WriteLiteral("\r\n\r\n"); // Code block: Update the host Windows Form passed in through the context Context.WinForm.Text = "Hello World from Razor at " + DateTime.Now.ToString(); WriteLiteral("\r\nAppDomain Id:\r\n "); Write(AppDomain.CurrentDomain.FriendlyName); WriteLiteral("\r\n \r\nAssembly:\r\n "); Write(Assembly.GetExecutingAssembly().FullName); WriteLiteral("\r\n\r\nCode based output: \r\n"); // Write output with Response object from code string output = string.Empty; for (int i = 0; i < 10; i++) { output += i.ToString() + " "; } } } } Basically the template’s body is turned into code in an Execute method that is called. Internally the template’s Write method is fired to actually generate the output. Note that the class inherits from RazorTemplateBase which is the generic parameter I used to specify the base class when creating an instance in my RazorEngine host: var engine = new RazorEngine<RazorTemplateBase>(); This template class must be provided and it must implement an Execute() and Write() method. Beyond that you can create any class you chose and attach your own properties. My RazorTemplateBase class implementation is very simple: public class RazorTemplateBase : MarshalByRefObject, IDisposable { /// <summary> /// You can pass in a generic context object /// to use in your template code /// </summary> public dynamic Context { get; set; } /// <summary> /// Class that generates output. Currently ultra simple /// with only Response.Write() implementation. /// </summary> public RazorResponse Response { get; set; } public object HostContainer {get; set; } public object Engine { get; set; } public RazorTemplateBase() { Response = new RazorResponse(); } public virtual void Write(object value) { Response.Write(value); } public virtual void WriteLiteral(object value) { Response.Write(value); } /// <summary> /// Razor Parser implements this method /// </summary> public virtual void Execute() {} public virtual void Dispose() { if (Response != null) { Response.Dispose(); Response = null; } } } Razor fills in the Execute method when it generates its subclass and uses the Write() method to output content. As you can see I use a RazorResponse() class here to generate output. This isn’t necessary really, as you could use a StringBuilder or StringWriter() directly, but I prefer using Response object so I can extend the Response behavior as needed. The RazorResponse class is also very simple and merely acts as a wrapper around a TextWriter: public class RazorResponse : IDisposable { /// <summary> /// Internal text writer - default to StringWriter() /// </summary> public TextWriter Writer = new StringWriter(); public virtual void Write(object value) { Writer.Write(value); } public virtual void WriteLine(object value) { Write(value); Write("\r\n"); } public virtual void WriteFormat(string format, params object[] args) { Write(string.Format(format, args)); } public override string ToString() { return Writer.ToString(); } public virtual void Dispose() { Writer.Close(); } public virtual void SetTextWriter(TextWriter writer) { // Close original writer if (Writer != null) Writer.Close(); Writer = writer; } } The Rendering Methods of RazorEngine At this point I’ve talked about the assembly generation logic and the template implementation itself. What’s left is that once you’ve generated the assembly is to execute it. The code to do this is handled in the various RenderXXX methods of the RazorEngine class. Let’s look at the lowest level one of these which is RenderTemplateFromAssembly() and a couple of internal support methods that handle instantiating and invoking of the generated template method: public string RenderTemplateFromAssembly( string assemblyId, string generatedNamespace, string generatedClass, object context, TextWriter outputWriter) { this.SetError(); Assembly generatedAssembly = AssemblyCache[assemblyId]; if (generatedAssembly == null) { this.SetError(Resources.PreviouslyCompiledAssemblyNotFound); return null; } string className = generatedNamespace + "." + generatedClass; Type type; try { type = generatedAssembly.GetType(className); } catch (Exception ex) { this.SetError(Resources.UnableToCreateType + className + ": " + ex.Message); return null; } // Start with empty non-error response (if we use a writer) string result = string.Empty; using(TBaseTemplateType instance = InstantiateTemplateClass(type)) { if (instance == null) return null; if (outputWriter != null) instance.Response.SetTextWriter(outputWriter); if (!InvokeTemplateInstance(instance, context)) return null; // Capture string output if implemented and return // otherwise null is returned if (outputWriter == null) result = instance.Response.ToString(); } return result; } protected virtual TBaseTemplateType InstantiateTemplateClass(Type type) { TBaseTemplateType instance = Activator.CreateInstance(type) as TBaseTemplateType; if (instance == null) { SetError(Resources.CouldnTActivateTypeInstance + type.FullName); return null; } instance.Engine = this; // If a HostContainer was set pass that to the template too instance.HostContainer = this.HostContainer; return instance; } /// <summary> /// Internally executes an instance of the template, /// captures errors on execution and returns true or false /// </summary> /// <param name="instance">An instance of the generated template</param> /// <returns>true or false - check ErrorMessage for errors</returns> protected virtual bool InvokeTemplateInstance(TBaseTemplateType instance, object context) { try { instance.Context = context; instance.Execute(); } catch (Exception ex) { this.SetError(Resources.TemplateExecutionError + ex.Message); return false; } finally { // Must make sure Response is closed instance.Response.Dispose(); } return true; } The RenderTemplateFromAssembly method basically requires the namespace and class to instantate and creates an instance of the class using InstantiateTemplateClass(). It then invokes the method with InvokeTemplateInstance(). These two methods are broken out because they are re-used by various other rendering methods and also to allow subclassing and providing additional configuration tasks to set properties and pass values to templates at execution time. In the default mode instantiation sets the Engine and HostContainer (discussed later) so the template can call back into the template engine, and the context is set when the template method is invoked. The various RenderXXX methods use similar code although they create the assemblies first. If you’re after potentially cashing assemblies the method is the one to call and that’s exactly what the two HostContainer classes do. More on that in a minute, but before we get into HostContainers let’s talk about AppDomain hosting and the like. Running Templates in their own AppDomain With the RazorEngine class above, when a template is parsed into an assembly and executed the assembly is created (in memory or on disk – you can configure that) and cached in the current AppDomain. In .NET once an assembly has been loaded it can never be unloaded so if you’re loading lots of templates and at some time you want to release them there’s no way to do so. If however you load the assemblies in a separate AppDomain that new AppDomain can be unloaded and the assemblies loaded in it with it. In order to host the templates in a separate AppDomain the easiest thing to do is to run the entire RazorEngine in a separate AppDomain. Then all interaction occurs in the other AppDomain and no further changes have to be made. To facilitate this there is a RazorEngineFactory which has methods that can instantiate the RazorHost in a separate AppDomain as well as in the local AppDomain. The host creates the remote instance and then hangs on to it to keep it alive as well as providing methods to shut down the AppDomain and reload the engine. Sounds complicated but cross-AppDomain invocation is actually fairly easy to implement. Here’s some of the relevant code from the RazorEngineFactory class. Like the RazorEngine this class is generic and requires a template base type in the generic class name: public class RazorEngineFactory<TBaseTemplateType> where TBaseTemplateType : RazorTemplateBase Here are the key methods of interest: /// <summary> /// Creates an instance of the RazorHost in a new AppDomain. This /// version creates a static singleton that that is cached and you /// can call UnloadRazorHostInAppDomain to unload it. /// </summary> /// <returns></returns> public static RazorEngine<TBaseTemplateType> CreateRazorHostInAppDomain() { if (Current == null) Current = new RazorEngineFactory<TBaseTemplateType>(); return Current.GetRazorHostInAppDomain(); } public static void UnloadRazorHostInAppDomain() { if (Current != null) Current.UnloadHost(); Current = null; } /// <summary> /// Instance method that creates a RazorHost in a new AppDomain. /// This method requires that you keep the Factory around in /// order to keep the AppDomain alive and be able to unload it. /// </summary> /// <returns></returns> public RazorEngine<TBaseTemplateType> GetRazorHostInAppDomain() { LocalAppDomain = CreateAppDomain(null); if (LocalAppDomain == null) return null; /// Create the instance inside of the new AppDomain /// Note: remote domain uses local EXE's AppBasePath!!! RazorEngine<TBaseTemplateType> host = null; try { Assembly ass = Assembly.GetExecutingAssembly(); string AssemblyPath = ass.Location; host = (RazorEngine<TBaseTemplateType>) LocalAppDomain.CreateInstanceFrom(AssemblyPath, typeof(RazorEngine<TBaseTemplateType>).FullName).Unwrap(); } catch (Exception ex) { ErrorMessage = ex.Message; return null; } return host; } /// <summary> /// Internally creates a new AppDomain in which Razor templates can /// be run. /// </summary> /// <param name="appDomainName"></param> /// <returns></returns> private AppDomain CreateAppDomain(string appDomainName) { if (appDomainName == null) appDomainName = "RazorHost_" + Guid.NewGuid().ToString("n"); AppDomainSetup setup = new AppDomainSetup(); // *** Point at current directory setup.ApplicationBase = AppDomain.CurrentDomain.BaseDirectory; AppDomain localDomain = AppDomain.CreateDomain(appDomainName, null, setup); return localDomain; } /// <summary> /// Allow unloading of the created AppDomain to release resources /// All internal resources in the AppDomain are released including /// in memory compiled Razor assemblies. /// </summary> public void UnloadHost() { if (this.LocalAppDomain != null) { AppDomain.Unload(this.LocalAppDomain); this.LocalAppDomain = null; } } The static CreateRazorHostInAppDomain() is the key method that startup code usually calls. It uses a Current singleton instance to an instance of itself that is created cross AppDomain and is kept alive because it’s static. GetRazorHostInAppDomain actually creates a cross-AppDomain instance which first creates a new AppDomain and then loads the RazorEngine into it. The remote Proxy instance is returned as a result to the method and can be used the same as a local instance. The code to run with a remote AppDomain is simple: private RazorEngine<RazorTemplateBase> CreateHost() { if (this.Host != null) return this.Host; // Use Static Methods - no error message if host doesn't load this.Host = RazorEngineFactory<RazorTemplateBase>.CreateRazorHostInAppDomain(); if (this.Host == null) { MessageBox.Show("Unable to load Razor Template Host", "Razor Hosting", MessageBoxButtons.OK, MessageBoxIcon.Exclamation); } return this.Host; } This code relies on a local reference of the Host which is kept around for the duration of the app (in this case a form reference). To use this you’d simply do: this.Host = CreateHost(); if (host == null) return; string result = host.RenderTemplate( this.txtSource.Text, new string[] { "System.Windows.Forms.dll", "Westwind.Utilities.dll" }, this.CustomContext); if (result == null) { MessageBox.Show(host.ErrorMessage, "Template Execution Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation); return; } this.txtResult.Text = result; Now all templates run in a remote AppDomain and can be unloaded with simple code like this: RazorEngineFactory<RazorTemplateBase>.UnloadRazorHostInAppDomain(); this.Host = null; One Step further – Providing a caching ‘Runtime’ Once we can load templates in a remote AppDomain we can add some additional functionality like assembly caching based on application specific features. One of my typical scenarios is to render templates out of a scripts folder. So all templates live in a folder and they change infrequently. So a Folder based host that can compile these templates once and then only recompile them if something changes would be ideal. Enter host containers which are basically wrappers around the RazorEngine<t> and RazorEngineFactory<t>. They provide additional logic for things like file caching based on changes on disk or string hashes for string based template inputs. The folder host also provides for partial rendering logic through a custom template base implementation. There’s a base implementation in RazorBaseHostContainer, which provides the basics for hosting a RazorEngine, which includes the ability to start and stop the engine, cache assemblies and add references: public abstract class RazorBaseHostContainer<TBaseTemplateType> : MarshalByRefObject where TBaseTemplateType : RazorTemplateBase, new() { public RazorBaseHostContainer() { UseAppDomain = true; GeneratedNamespace = "__RazorHost"; } /// <summary> /// Determines whether the Container hosts Razor /// in a separate AppDomain. Seperate AppDomain /// hosting allows unloading and releasing of /// resources. /// </summary> public bool UseAppDomain { get; set; } /// <summary> /// Base folder location where the AppDomain /// is hosted. By default uses the same folder /// as the host application. /// /// Determines where binary dependencies are /// found for assembly references. /// </summary> public string BaseBinaryFolder { get; set; } /// <summary> /// List of referenced assemblies as string values. /// Must be in GAC or in the current folder of the host app/ /// base BinaryFolder /// </summary> public List<string> ReferencedAssemblies = new List<string>(); /// <summary> /// Name of the generated namespace for template classes /// </summary> public string GeneratedNamespace {get; set; } /// <summary> /// Any error messages /// </summary> public string ErrorMessage { get; set; } /// <summary> /// Cached instance of the Host. Required to keep the /// reference to the host alive for multiple uses. /// </summary> public RazorEngine<TBaseTemplateType> Engine; /// <summary> /// Cached instance of the Host Factory - so we can unload /// the host and its associated AppDomain. /// </summary> protected RazorEngineFactory<TBaseTemplateType> EngineFactory; /// <summary> /// Keep track of each compiled assembly /// and when it was compiled. /// /// Use a hash of the string to identify string /// changes. /// </summary> protected Dictionary<int, CompiledAssemblyItem> LoadedAssemblies = new Dictionary<int, CompiledAssemblyItem>(); /// <summary> /// Call to start the Host running. Follow by a calls to RenderTemplate to /// render individual templates. Call Stop when done. /// </summary> /// <returns>true or false - check ErrorMessage on false </returns> public virtual bool Start() { if (Engine == null) { if (UseAppDomain) Engine = RazorEngineFactory<TBaseTemplateType>.CreateRazorHostInAppDomain(); else Engine = RazorEngineFactory<TBaseTemplateType>.CreateRazorHost(); Engine.Configuration.CompileToMemory = true; Engine.HostContainer = this; if (Engine == null) { this.ErrorMessage = EngineFactory.ErrorMessage; return false; } } return true; } /// <summary> /// Stops the Host and releases the host AppDomain and cached /// assemblies. /// </summary> /// <returns>true or false</returns> public bool Stop() { this.LoadedAssemblies.Clear(); RazorEngineFactory<RazorTemplateBase>.UnloadRazorHostInAppDomain(); this.Engine = null; return true; } … } This base class provides most of the mechanics to host the runtime, but no application specific implementation for rendering. There are rendering functions but they just call the engine directly and provide no caching – there’s no context to decide how to cache and reuse templates. The key methods are Start and Stop and their main purpose is to start a new AppDomain (optionally) and shut it down when requested. The RazorFolderHostContainer – Folder Based Runtime Hosting Let’s look at the more application specific RazorFolderHostContainer implementation which is defined like this: public class RazorFolderHostContainer : RazorBaseHostContainer<RazorTemplateFolderHost> Note that a customized RazorTemplateFolderHost class template is used for this implementation that supports partial rendering in form of a RenderPartial() method that’s available to templates. The folder host’s features are: Render templates based on a Template Base Path (a ‘virtual’ if you will) Cache compiled assemblies based on the relative path and file time stamp File changes on templates cause templates to be recompiled into new assemblies Support for partial rendering using base folder relative pathing As shown in the startup examples earlier host containers require some startup code with a HostContainer tied to a persistent property (like a Form property): // The base path for templates - templates are rendered with relative paths // based on this path. HostContainer.TemplatePath = Path.Combine(Environment.CurrentDirectory, TemplateBaseFolder); // Default output rendering disk location HostContainer.RenderingOutputFile = Path.Combine(HostContainer.TemplatePath, "__Preview.htm"); // Add any assemblies you want reference in your templates HostContainer.ReferencedAssemblies.Add("System.Windows.Forms.dll"); // Start up the host container HostContainer.Start(); Once that’s done, you can render templates with the host container: // Pass the template path for full filename seleted with OpenFile Dialog // relativepath is: subdir\file.cshtml or file.cshtml or ..\file.cshtml var relativePath = Utilities.GetRelativePath(fileName, HostContainer.TemplatePath); if (!HostContainer.RenderTemplate(relativePath, Context, HostContainer.RenderingOutputFile)) { MessageBox.Show("Error: " + HostContainer.ErrorMessage); return; } webBrowser1.Navigate("file://" + HostContainer.RenderingOutputFile); The most critical task of the RazorFolderHostContainer implementation is to retrieve a template from disk, compile and cache it and then deal with deciding whether subsequent requests need to re-compile the template or simply use a cached version. Internally the GetAssemblyFromFileAndCache() handles this task: /// <summary> /// Internally checks if a cached assembly exists and if it does uses it /// else creates and compiles one. Returns an assembly Id to be /// used with the LoadedAssembly list. /// </summary> /// <param name="relativePath"></param> /// <param name="context"></param> /// <returns></returns> protected virtual CompiledAssemblyItem GetAssemblyFromFileAndCache(string relativePath) { string fileName = Path.Combine(TemplatePath, relativePath).ToLower(); int fileNameHash = fileName.GetHashCode(); if (!File.Exists(fileName)) { this.SetError(Resources.TemplateFileDoesnTExist + fileName); return null; } CompiledAssemblyItem item = null; this.LoadedAssemblies.TryGetValue(fileNameHash, out item); string assemblyId = null; // Check for cached instance if (item != null) { var fileTime = File.GetLastWriteTimeUtc(fileName); if (fileTime <= item.CompileTimeUtc) assemblyId = item.AssemblyId; } else item = new CompiledAssemblyItem(); // No cached instance - create assembly and cache if (assemblyId == null) { string safeClassName = GetSafeClassName(fileName); StreamReader reader = null; try { reader = new StreamReader(fileName, true); } catch (Exception ex) { this.SetError(Resources.ErrorReadingTemplateFile + fileName); return null; } assemblyId = Engine.ParseAndCompileTemplate(this.ReferencedAssemblies.ToArray(), reader); // need to ensure reader is closed if (reader != null) reader.Close(); if (assemblyId == null) { this.SetError(Engine.ErrorMessage); return null; } item.AssemblyId = assemblyId; item.CompileTimeUtc = DateTime.UtcNow; item.FileName = fileName; item.SafeClassName = safeClassName; this.LoadedAssemblies[fileNameHash] = item; } return item; } This code uses a LoadedAssembly dictionary which is comprised of a structure that holds a reference to a compiled assembly, a full filename and file timestamp and an assembly id. LoadedAssemblies (defined on the base class shown earlier) is essentially a cache for compiled assemblies and they are identified by a hash id. In the case of files the hash is a GetHashCode() from the full filename of the template. The template is checked for in the cache and if not found the file stamp is checked. If that’s newer than the cache’s compilation date the template is recompiled otherwise the version in the cache is used. All the core work defers to a RazorEngine<T> instance to ParseAndCompileTemplate(). The three rendering specific methods then are rather simple implementations with just a few lines of code dealing with parameter and return value parsing: /// <summary> /// Renders a template to a TextWriter. Useful to write output into a stream or /// the Response object. Used for partial rendering. /// </summary> /// <param name="relativePath">Relative path to the file in the folder structure</param> /// <param name="context">Optional context object or null</param> /// <param name="writer">The textwriter to write output into</param> /// <returns></returns> public bool RenderTemplate(string relativePath, object context, TextWriter writer) { // Set configuration data that is to be passed to the template (any object) Engine.TemplatePerRequestConfigurationData = new RazorFolderHostTemplateConfiguration() { TemplatePath = Path.Combine(this.TemplatePath, relativePath), TemplateRelativePath = relativePath, }; CompiledAssemblyItem item = GetAssemblyFromFileAndCache(relativePath); if (item == null) { writer.Close(); return false; } try { // String result will be empty as output will be rendered into the // Response object's stream output. However a null result denotes // an error string result = Engine.RenderTemplateFromAssembly(item.AssemblyId, context, writer); if (result == null) { this.SetError(Engine.ErrorMessage); return false; } } catch (Exception ex) { this.SetError(ex.Message); return false; } finally { writer.Close(); } return true; } /// <summary> /// Render a template from a source file on disk to a specified outputfile. /// </summary> /// <param name="relativePath">Relative path off the template root folder. Format: path/filename.cshtml</param> /// <param name="context">Any object that will be available in the template as a dynamic of this.Context</param> /// <param name="outputFile">Optional - output file where output is written to. If not specified the /// RenderingOutputFile property is used instead /// </param> /// <returns>true if rendering succeeds, false on failure - check ErrorMessage</returns> public bool RenderTemplate(string relativePath, object context, string outputFile) { if (outputFile == null) outputFile = RenderingOutputFile; try { using (StreamWriter writer = new StreamWriter(outputFile, false, Engine.Configuration.OutputEncoding, Engine.Configuration.StreamBufferSize)) { return RenderTemplate(relativePath, context, writer); } } catch (Exception ex) { this.SetError(ex.Message); return false; } return true; } /// <summary> /// Renders a template to string. Useful for RenderTemplate /// </summary> /// <param name="relativePath"></param> /// <param name="context"></param> /// <returns></returns> public string RenderTemplateToString(string relativePath, object context) { string result = string.Empty; try { using (StringWriter writer = new StringWriter()) { // String result will be empty as output will be rendered into the // Response object's stream output. However a null result denotes // an error if (!RenderTemplate(relativePath, context, writer)) { this.SetError(Engine.ErrorMessage); return null; } result = writer.ToString(); } } catch (Exception ex) { this.SetError(ex.Message); return null; } return result; } The idea is that you can create custom host container implementations that do exactly what you want fairly easily. Take a look at both the RazorFolderHostContainer and RazorStringHostContainer classes for the basic concepts you can use to create custom implementations. Notice also that you can set the engine’s PerRequestConfigurationData() from the host container: // Set configuration data that is to be passed to the template (any object) Engine.TemplatePerRequestConfigurationData = new RazorFolderHostTemplateConfiguration() { TemplatePath = Path.Combine(this.TemplatePath, relativePath), TemplateRelativePath = relativePath, }; which when set to a non-null value is passed to the Template’s InitializeTemplate() method. This method receives an object parameter which you can cast as needed: public override void InitializeTemplate(object configurationData) { // Pick up configuration data and stuff into Request object RazorFolderHostTemplateConfiguration config = configurationData as RazorFolderHostTemplateConfiguration; this.Request.TemplatePath = config.TemplatePath; this.Request.TemplateRelativePath = config.TemplateRelativePath; } With this data you can then configure any custom properties or objects on your main template class. It’s an easy way to pass data from the HostContainer all the way down into the template. The type you use is of type object so you have to cast it yourself, and it must be serializable since it will likely run in a separate AppDomain. This might seem like an ugly way to pass data around – normally I’d use an event delegate to call back from the engine to the host, but since this is running over AppDomain boundaries events get really tricky and passing a template instance back up into the host over AppDomain boundaries doesn’t work due to serialization issues. So it’s easier to pass the data from the host down into the template using this rather clumsy approach of set and forward. It’s ugly, but it’s something that can be hidden in the host container implementation as I’ve done here. It’s also not something you have to do in every implementation so this is kind of an edge case, but I know I’ll need to pass a bunch of data in some of my applications and this will be the easiest way to do so. Summing Up Hosting the Razor runtime is something I got jazzed up about quite a bit because I have an immediate need for this type of templating/merging/scripting capability in an application I’m working on. I’ve also been using templating in many apps and it’s always been a pain to deal with. The Razor engine makes this whole experience a lot cleaner and more light weight and with these wrappers I can now plug .NET based templating into my code literally with a few lines of code. That’s something to cheer about… I hope some of you will find this useful as well… Resources The examples and code require that you download the Razor runtimes. Projects are for Visual Studio 2010 running on .NET 4.0 Platform Installer 3.0 (install WebMatrix or MVC 3 for Razor Runtimes) Latest Code in Subversion Repository Download Snapshot of the Code Documentation (CHM Help File) © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET  .NET  

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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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  • WPF Richtextbox XamlWriter behaviour

    - by Krishna
    I am trying to save some c# source code into the database. Basically I have a RichTextBox that users can type their code and save that to the database. When I copy and paste from the visual studio environment, I would like to preserve the formating etc. So I have chosen to save the FlowDocuments Xaml to the database and set this back to the RichTextBox.Document. My below two function serialise and deserialise the RTB's contents. private string GetXaml(FlowDocument document) { if (document == null) return String.Empty; else{ StringBuilder sb = new StringBuilder(); XmlWriter xw = XmlWriter.Create(sb); XamlDesignerSerializationManager sm = new XamlDesignerSerializationManager(xw); sm.XamlWriterMode = XamlWriterMode.Expression; XamlWriter.Save(document, sm ); return sb.ToString(); } } private FlowDocument GetFlowDocument(string xamlText) { var flowDocument = new FlowDocument(); if (xamlText != null) flowDocument = (FlowDocument)XamlReader.Parse(xamlText); // Set return value return flowDocument; } However when I try to serialise and deserialise the following code, I am noticing this incorrect(?) behaviour using System; public class TestCSScript : MarshalByRefObject { } Serialised XAML is using System; public class TestCSScript : MarshalByRefObject {}{ } Notice the the new set of "{}" What am I doing wrong here... Thanks in advance for the help!

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  • .NET remoting exception: Permission denied: cannot call non-public or static methods remotely.

    - by Vilx-
    I'm writing a program which will allow to load a specific managed .DLL file and play with it. Since I want the ability to unload the .DLL file, I'm creating two AppDomains - one for the app itself, the other for the currently loaded .DLL. Since most of the objects in the loaded .DLL do not serialize well, I'm creating a MarshalByRefObject wrapper class which will keep the object itself in its own AppDomain, and expose some reflection functions to the main application AppDomain. However when I try to invoke a method on the remote object I get stuck with an exception: Permission denied: cannot call non-public or static methods remotely. This is very strange, because I'm not using any non-public or static methods at all. In essence, what I have is: class RemoteObjectWrapper: MarshalByRefObject { private Type SourceType; private object Source; public RemoteObjectWrapper(object source) { if (source == null) throw new ArgumentNullException("source"); this.Source = source; this.SourceType = source.GetType(); } public T WrapValue<T>(object value) { if ( value == null ) return default(T); var TType = typeof(T); if (TType == typeof(RemoteObjectWrapper)) value = new RemoteObjectWrapper(value); return (T)value; } public T InvokeMethod<T>(string methodName, params object[] args) { return WrapValue<T>(SourceType.InvokeMember(methodName, System.Reflection.BindingFlags.FlattenHierarchy | System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.InvokeMethod | System.Reflection.BindingFlags.Public, null, this.Source, args)); } } And I get the exception when I try to do: var c = SomeInstanceOfRemoteObjectWrapper.InvokeMethod<RemoteObjectWrapper>("somePublicMethod", "some string parameter"); What's going on here? As far as I can understand, the InvokeMethod method doesn't even get executed, the exception is thrown when I try to run it. Added: To clarify - SomeInstanceOfRemoteObjectWrapper is constructed in the .DLL's AppDomain and then returned to my main AppDomain, The InvokeMethod<T>() is called from my main AppDomain (and I expect it to execute in the .DLL's AppDomain).

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  • .NET binary serialization conditionally without ISerializable

    - by SillyWhy
    I got 2 classes, for example: public class A { private B b; ... } public class B { ... } I need to serialize an object A using BinaryFormatter. When remoting it shall include the field b, but not when serialize to file. Here is what I added: [Serializable] public class A : MarshalByRefObject { private B b; [OnSerializing] private void OnSerializing(StreamingContext context) { if (context.State == StreamingContextStates.File) { this.b = null; } } ... } [Serializable] public class B : MarshalByRefObject { ... } I think this is a bad design because if another class C also contains B, in class C we must add the duplicate OnSerializing() logic as in A. Class B should decide what to do, not class A or C. I don't want to use ISerializable interface because there are too many variables in class B have to be added to SerializationInfo. I can create a SerializationSurrogate for class B, which perform nothing in GetObjectData() & SetObjectData(), then use it when serializing to file. However the same maintenance issue because whoever modify class B can't notice what going to happen during serialization & the existence of SerializationSurrogate. Is there a better alternative?

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  • Does COM interop respect .NET AppDomain boundaries for assembly loading?

    - by Xiaofu
    Here's the core problem: I have a .NET application that is using COM interop in a separate AppDomain. The COM stuff seems to be loading assemblies back into the default domain, rather than the AppDomain from which the COM stuff is being called. What I want to know is: is this expected behaviour, or am I doing something wrong to cause these COM related assemblies to be loaded in the wrong AppDomain? Please see a more detailed description of the situation below... The application consists of 3 assemblies: - the main EXE, the entry point of the application. - common.dll, containing just an interface IController (in the IPlugin style) - controller.dll, containing a Controller class that implements IController and MarshalByRefObject. This class does all the work and uses COM interop to interact with another application. The relevant part of the main EXE looks like this: AppDomain controller_domain = AppDomain.CreateDomain("Controller Domain"); IController c = (IController)controller_domain.CreateInstanceFromAndUnwrap("controller.dll", "MyNamespace.Controller"); result = c.Run(); AppDomain.Unload(controller_domain); The common.dll only contains these 2 things: public enum ControllerRunResult{FatalError, Finished, NonFatalError, NotRun} public interface IController { ControllerRunResult Run(); } And the controller.dll contains this class (which also calls the COM interop stuff): public class Controller: IController, MarshalByRefObject When first running the application, Assembly.GetAssemblies() looks as expected, with common.dll being loaded in both AppDomains, and controller.dll only being loaded into the controller domain. After calling c.Run() however I see that assemblies related to the COM interop stuff have been loaded into the default AppDomain, and NOT in the AppDomain from which the COM interop is taking place. Why might this be occurring? And if you're interested, here's a bit of background: Originally this was a 1 AppDomain application. The COM stuff it interfaces with is a server API which is not stable over long periods of use. When a COMException (with no useful diagnostic information as to its cause) occurs from the COM stuff, the entire application has to restarted before the COM connection will work again. Simply reconnecting to the COM app server results in immediate COM exceptions again. To cope with this I have tried to move the COM interop stuff into a seperate AppDomain so that when the mystery COMExceptions occur I can unload the AppDomain in which it occurs, create a new one and start again, all without having to manually restart the application. That was the theory anyway...

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  • Remoting Error: Requested Service Not Found

    - by enableDeepak
    Hi, I am trying to create a very simple example of remoting which isn't working. I start the host and when I start client, it says "requested service not found" Parts of My Application are: Remoting Object : MarshalByRefObject ComponentHost Client You can download my project from here It has been 2 days and I am going crazy. Requested if someone can tell that where am I wrong?

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  • Mixing secure & unsecure channels

    - by user305023
    I am unable to use an unsecure channel once a secure channel has already been registered. The code below works only if on the client side, the unsecured channel is registered before. Is it possible to mix secure and unsecure channels without any constraint on the registration order ? using System; using System.Collections; using System.Runtime.Remoting; using System.Runtime.Remoting.Channels; using System.Runtime.Remoting.Channels.Tcp; public class SampleObject : MarshalByRefObject { public DateTime GetTest() { return DateTime.Now; } } public class SampleObject2 : MarshalByRefObject { public DateTime GetTest2() { return DateTime.Now; } } static class ProgramClient { private static TcpClientChannel RegisterChannel(bool secure, string name, int priority) { IDictionary properties = new Hashtable(); properties.Add("secure", secure); properties.Add("name", name); properties.Add("priority", priority); var clientChannel = new TcpClientChannel(properties, null); ChannelServices.RegisterChannel(clientChannel, false); return clientChannel; } private static void Secure() { RegisterChannel(true, "clientSecure", 2); var testSecure = (SampleObject2)Activator.GetObject(typeof(SampleObject2), "tcp://127.0.0.1:8081/Secured.rem"); Console.WriteLine("secure: " + testSecure.GetTest2().ToLongTimeString()); } private static void Unsecure() { RegisterChannel(false, "clientUnsecure", 1); var test = (SampleObject)Activator.GetObject(typeof(SampleObject), "tcp://127.0.0.1:8080/Unsecured.rem"); Console.WriteLine("unsecure: " + test.GetTest().ToLongTimeString()); } internal static void MainClient() { Console.Write("Press Enter to start."); Console.ReadLine(); // Works only in this order Unsecure(); Secure(); Console.WriteLine("Press ENTER to end"); Console.ReadLine(); } } static class ProgramServer { private static TcpServerChannel RegisterChannel(int port, bool secure, string name) { IDictionary properties = new Hashtable(); properties.Add("port", port); properties.Add("secure", secure); properties.Add("name", name); //properties.Add("impersonate", false); var serverChannel = new TcpServerChannel(properties, null); ChannelServices.RegisterChannel(serverChannel, secure); return serverChannel; } private static void StartUnsecure() { RegisterChannel(8080, false, "unsecure"); RemotingConfiguration.RegisterWellKnownServiceType(typeof(SampleObject), "Unsecured.rem", WellKnownObjectMode.Singleton); } private static void StartSecure() { RegisterChannel(8081, true, "secure"); RemotingConfiguration.RegisterWellKnownServiceType(typeof(SampleObject2), "Secured.rem", WellKnownObjectMode.Singleton); } internal static void MainServer() { StartUnsecure(); StartSecure(); Console.WriteLine("Unsecure: 8080\n Secure: 8081"); Console.WriteLine("Press the enter key to exit..."); Console.ReadLine(); } } class Program { static void Main(string[] args) { if (args.Length == 1 && args[0] == "server") ProgramServer.MainServer(); else ProgramClient.MainClient(); } }

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  • [.NET Remoting] Mixing secure & unsecure channels

    - by user305023
    I am unable to use an unsecure channel once a secure channel has already been registered. The code below works only if on the client side, the unsecured channel is registered before. Is it possible to mix secure and unsecure channels without any contraints on the registration order ? using System; using System.Collections; using System.Runtime.Remoting; using System.Runtime.Remoting.Channels; using System.Runtime.Remoting.Channels.Tcp; public class SampleObject : MarshalByRefObject { public DateTime GetTest() { return DateTime.Now; } } public class SampleObject2 : MarshalByRefObject { public DateTime GetTest2() { return DateTime.Now; } } static class ProgramClient { private static TcpClientChannel RegisterChannel(bool secure, string name, int priority) { IDictionary properties = new Hashtable(); properties.Add("secure", secure); properties.Add("name", name); properties.Add("priority", priority); var clientChannel = new TcpClientChannel(properties, null); ChannelServices.RegisterChannel(clientChannel, false); return clientChannel; } private static void Secure() { RegisterChannel(true, "clientSecure", 2); var testSecure = (SampleObject2)Activator.GetObject(typeof(SampleObject2), "tcp://127.0.0.1:8081/Secured.rem"); Console.WriteLine("secure: " + testSecure.GetTest2().ToLongTimeString()); } private static void Unsecure() { RegisterChannel(false, "clientUnsecure", 1); var test = (SampleObject)Activator.GetObject(typeof(SampleObject), "tcp://127.0.0.1:8080/Unsecured.rem"); Console.WriteLine("unsecure: " + test.GetTest().ToLongTimeString()); } internal static void MainClient() { Console.Write("Press Enter to start."); Console.ReadLine(); // Works only in this order Unsecure(); Secure(); Console.WriteLine("Press ENTER to end"); Console.ReadLine(); } } static class ProgramServer { private static TcpServerChannel RegisterChannel(int port, bool secure, string name) { IDictionary properties = new Hashtable(); properties.Add("port", port); properties.Add("secure", secure); properties.Add("name", name); //properties.Add("impersonate", false); var serverChannel = new TcpServerChannel(properties, null); ChannelServices.RegisterChannel(serverChannel, secure); return serverChannel; } private static void StartUnsecure() { RegisterChannel(8080, false, "unsecure"); RemotingConfiguration.RegisterWellKnownServiceType(typeof(SampleObject), "Unsecured.rem", WellKnownObjectMode.Singleton); } private static void StartSecure() { RegisterChannel(8081, true, "secure"); RemotingConfiguration.RegisterWellKnownServiceType(typeof(SampleObject2), "Secured.rem", WellKnownObjectMode.Singleton); } internal static void MainServer() { StartUnsecure(); StartSecure(); Console.WriteLine("Unsecure: 8080\n Secure: 8081"); Console.WriteLine("Press the enter key to exit..."); Console.ReadLine(); } } class Program { static void Main(string[] args) { if (args.Length == 1 && args[0] == "server") ProgramServer.MainServer(); else ProgramClient.MainClient(); } }

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  • Properties in Remoting

    - by Evl-ntnt
    Server: Host h = new Host(); h.Name = "JARR!!"; TcpChannel channel = new TcpChannel(8080); ChannelServices.RegisterChannel(channel); RemotingConfiguration.RegisterWellKnownServiceType(typeof(Host), "Server", WellKnownObjectMode.Singleton); Client: TcpChannel chan = new TcpChannel(); ChannelServices.RegisterChannel(chan); remoteHost = (Host)Activator.GetObject(typeof(Host), "tcp://127.0.0.1:8080/Server"); Class: [Serializable] public class Host: MarshalByRefObject { public string Name{get; set;} public Host(){} public Host(string n) { Name = n; } public override string ToString() { return Name; } } Connection OK, 8080 port opened, on client side remoteHost is not null, but remoteHost.Name == "" Why?

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  • how to modify a textbox using remoting

    - by danutz0119
    I am trying to modify a textBox found in the server Form using remoting from the client side. i have tried some solutions i found, but none of them work. the remoting part works propperly, the only thing that I am not able to figure out is this: this is what i have: client side: ... private void btn_b1_Click(object sender, EventArgs e) { ... myFunc.update(string s); ... } ... sharedLibs: public interface myInterf { void update(string s); } server side: here i have 2 classes in the same namespace class class1 : MarshalByRefObject, myInterf { public void update(string s) { //what do i write here to modify textBox1? } } public partial class class2 : Form { ... // here is the textBox i am trying to alter; }

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  • .NET CF 2.0: Stream implements IDisposable ... kind of?

    - by mvanbem
    I've run into something odd in a .NET CF 2.0 project for Pocket PC 2003 (Visual Studio 2005). I was dealing with a System.IO.Stream object and found that the IDE wouldn't auto-complete the Dispose() method. I typed it in manually and received: 'System.IO.Stream.Dispose(bool)' is inaccessible due to its protection level The error is referring to the protected Dispose(bool) method. Dispose() is either private or not present. Question 1: How is this possible? Stream implements IDisposable: public abstract class Stream : MarshalByRefObject, IDisposable ... and IDisposable requires a Dispose() method: public interface IDisposable { void Dispose(); } I know the compiler won't let me get away with that in my code. Question 2: Will I cause problems by working around and disposing my streams directly? IDisposable idisp = someStream; idisp.Dispose(); The implicit cast is accepted by the compiler.

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  • CallContext and ApplicationHost

    - by p2u
    I tried to create an ApplicationHost. But I had errors like SerializationException and FileNotFoundException. Then I found this blog entry, where it's seem to be a remoting problem. In my little application I use the CallContext, so I tried some approaches. When I empty the CallContext before I create the ApplicationHost, it works: Programm class: namespace ApplicationHostDemo { public class Program { public static void Main(string[] args) { Evil evil = new Evil(); CallContext.SetData(Evil.CALLCONTEXT, evil); CallContext.FreeNamedDataSlot(Evil.CALLCONTEXT); Console.WriteLine("Simple Host-Demo\r\n"); Host host = CreateHost(); CallContext.SetData(Evil.CALLCONTEXT, evil); host.ProcessRequest("Index.aspx"); Console.WriteLine("\r\n\r\nSimple Host-Demo end"); Console.ReadLine(); } public static Host CreateHost() { return (Host)ApplicationHost.CreateApplicationHost(typeof(Host), "/", Directory.GetCurrentDirectory()); } public class Host : MarshalByRefObject { public void ProcessRequest(string page) { SimpleWorkerRequest swr = new SimpleWorkerRequest(page, "", Console.Out); HttpRuntime.ProcessRequest(swr); } } } } Evil class: namespace ApplicationHostDemo { [Serializable] public class Evil : ILogicalThreadAffinative { public const string CALLCONTEXT = "evil"; public string Name { get; set; } } } Do you know or could you explain why it works?

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  • Assemblies mysteriously loaded into new AppDomains

    - by Eric
    I'm testing some code that does work whenever assemblies are loaded into an appdomain. For unit testing (in VS2k8's built-in test host) I spin up a new, uniquely-named appdomain prior to each test with the idea that it should be "clean": [TestInitialize()] public void CalledBeforeEachTestMethod() { AppDomainSetup appSetup = new AppDomainSetup(); appSetup.ApplicationBase = @"G:\<ProjectDir>\bin\Debug"; Evidence baseEvidence = AppDomain.CurrentDomain.Evidence; Evidence evidence = new Evidence( baseEvidence ); _testAppDomain = AppDomain.CreateDomain( "myAppDomain" + _appDomainCounter++, evidence, appSetup ); } [TestMethod] public void MissingFactoryCausesAppDomainUnload() { SupportingClass supportClassObj = (SupportingClass)_testAppDomain.CreateInstanceAndUnwrap( GetType().Assembly.GetName().Name, typeof( SupportingClass ).FullName ); try { supportClassObj.LoadMissingRegistrationAssembly(); Assert.Fail( "Should have nuked the app domain" ); } catch( AppDomainUnloadedException ) { } } [TestMethod] public void InvalidFactoryMethodCausesAppDomainUnload() { SupportingClass supportClassObj = (SupportingClass)_testAppDomain.CreateInstanceAndUnwrap( GetType().Assembly.GetName().Name, typeof( SupportingClass ).FullName ); try { supportClassObj.LoadInvalidFactoriesAssembly(); Assert.Fail( "Should have nuked the app domain" ); } catch( AppDomainUnloadedException ) { } } public class SupportingClass : MarshalByRefObject { public void LoadMissingRegistrationAssembly() { MissingRegistration.Main(); } public void LoadInvalidFactoriesAssembly() { InvalidFactories.Main(); } } If every test is run individually I find that it works correctly; the appdomain is created and has only the few intended assemblies loaded. However, if multiple tests are run in succession then each _testAppDomain already has assemblies loaded from all previous tests. Oddly enough, the two tests get appdomains with different names. The test assemblies that define MissingRegistration and InvalidFactories (two different assemblies) are never loaded into the unit test's default appdomain. Can anyone explain this behavior?

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  • Which frameworks (and associated languages) support class replacement?

    - by Alix
    Hi, I'm writing my master thesis, which deals with AOP in .NET, among other things, and I mention the lack of support for replacing classes at load time as an important factor in the fact that there are currently no .NET AOP frameworks that perform true dynamic weaving -- not without imposing the requirement that woven classes must extend ContextBoundObject or MarshalByRefObject or expose all their semantics on an interface. You can however do this with the JVM thanks to ClassFileTransformer: You extend ClassFileTransformer. You subscribe to the class load event. On class load, you rewrite the class and replace it. All this is very well, but my project director has asked me, quite in the last minute, to give him a list of frameworks (and associated languages) that do / do not support class replacement. I really have no time to look for this now: I wouldn't feel comfortable just doing a superficial research and potentially putting erroneous information in my thesis. So I ask you, oh almighty programming community, can you help out? Of course, I'm not asking you to research this yourselves. Simply, if you know for sure that a particular framework supports / doesn't support this, leave it as an answer. If you're not sure please don't forget to point it out. Thanks so much!

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  • Which languages support class replacement?

    - by Alix
    Hi, I'm writing my master thesis, which deals with AOP in .NET, among other things, and I mention the lack of support for replacing classes at load time as an important factor in the fact that there are currently no .NET AOP frameworks that perform true dynamic weaving -- not without imposing the requirement that woven classes must extend ContextBoundObject or MarshalByRefObject or expose all their semantics on an interface. You can however do this in Java thanks to ClassFileTransformer: You extend ClassFileTransformer. You subscribe to the class load event. On class load, you rewrite the class and replace it. All this is very well, but my project director has asked me, quite in the last minute, to give him a list of languages that do / do not support class replacement. I really have no time to look for this now: I wouldn't feel comfortable just doing a superficial research and potentially putting erroneous information in my thesis. So I ask you, oh almighty programming community, can you help out? Of course, I'm not asking you to research this yourselves. Simply, if you know for sure that a particular language supports / doesn't support this, leave it as an answer. If you're not sure please don't forget to point it out. Thanks so much!

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  • How to marshal an object and its content (also objects)

    - by Waldo Spek
    I have a question for which I suspect the answer is a bit complex. At this moment I am programming a DLL (class library) in C#. This DLL uses a 3rd party library and therefore deals with 3rd party objects of which I do not have the source code. Now I am planning to create another DLL, which is going to be used in a later stadium in my application. This second DLL should use the 3rd party objects (with corresponding object states) created by the first DLL. Luckily the 3rd party objects extend the MarshalByRefObject class. I can marshal the objects using System.Runtime.Remoting.Marshal(...). I then serialize the objects using a BinaryFormatter and store the objects as a byte[] array. All goes well. I can deserialize and unmarshal in a the opposite way and end up with my original 3rd party objects...so it appears... Nevertheless, when calling methods on my 3rd party deserialized objects I get object internal exceptions. Normally these methods return other 3rd party objects, but (obviously - I guess) now these objects are missing because they weren't serialized. Now my global question: how would I go about marshalling/serializing all the objects which my 3rd party objects reference...and cascade down the "reference tree" to obtain a full and complete serialized object? Right now my guess is to preprocess: obtain all the objects and build my own custom object and serialize it. But I'm hoping there is some other way...

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  • Passing objects across Appdomains

    - by MUSTAQ
    My issue is similar to the one posted in "http://stackoverflow.com/questions/981773/moving-objects-across-appdomains-in-net". In one of my application, I am creating a separate appdomain. I need to create an instance of a class (Note: this class is derived by MarshalByRefObject) in my parent domain and invoke a MethodA in that instance. This instance is created using "CreateInstanceAndUnwrap". The problem is that this MethodA takes objects of type class as an argument. These objects are not created in the MethodB where i created the appdomain. It was passed as an argument to the MethodB where i create the appdomain. So is it necessary to create a new instance of these objects using "CreateInstanceAndUnwrap" before passing it to the created domain. Not doing this gives me an error in the created domain mentioning that "MyClass object has no attribute foo" during some invocation. Please let me know how to pass the objects across appdomains and execute the method. My statements might be confusing, please let me know for any specific details required.

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