How to make a simple dynamic proxy in C#

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I want to build a dynamic proxy object to add certain functionality to an object.

basically i want to receive an object, wrap it with an object that looks identical to the original i got, and intercept all the calls.

class Wrapper : DynamicProxy// dynamic proxy is not a reall class, but i guess something like this exists...
{
    public static T Wrap(T obj)
    {
        return (T) new Wrapper(obj);
    }

    public override object InterceptCall(MethodInfo info, object[] args)
    {
        // do stuff
    }

}

Just to clarify, I want to do something similar to the WCF channel factory...


I'm adding a bounty, because I need a good way to proxy classes (not interfaces) and to handle non virtual methods (as if I inherited and added a methond under the "new" keyword). I'm sure all this is very possible as the .Net does it.

You could do this with a combination of DynamicObject and ImpromptuInterface but you will have to have an Interface that implements the functions and properties you want to proxy.

public interface IDoStuff
{
    void Foo();
}

public class Wrapper<T> : DynamicObject
{
    private readonly T _wrappedObject;

    public static T1 Wrap<T1>(T obj) where T1 : class
    {
        if (!typeof(T1).IsInterface)
            throw new ArgumentException("T1 must be an Interface");

        return new Wrapper<T>(obj).ActLike<T1>();
    }

    //you can make the contructor private so you are forced to use the Wrap method.
    private Wrapper(T obj)
    {
        _wrappedObject = obj;
    }

    public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result)
    {
        try
        {
            //do stuff here

            //call _wrappedObject object
            result = _wrappedObject.GetType().GetMethod(binder.Name).Invoke(_wrappedObject, args);
            return true;
        }
        catch
        {
            result = null;
            return false;
        }
    }
}

You could of course choose to lose the type-safety and go with a DynamicObject like I showed and then drop the duck-casting.

I made a transparant extendible version of this object proxy, and open-sourced it here.

Dynamic Proxy Creation Using C# Emit, Building a Dynamic Proxy Creating a dynamic proxy involves creating a class that traps incoming method invocations. There is no built in C# mechanism to do this, so this must be done dynamically at runtime. In order to accomplish this, we first define an interface IProxyInvocationHandler . Building a proxy using System.Reflection.Emit as done by spring you can also look at the code of their ProxyFactoryObject. Here are another three articles on the subject. Recommend:c# - How to make your Service-Reference proxy URL dynamic

In addition to Castle.DynamicProxy, there is also LinFu.DynamicProxy on Github.

Making a Dynamic Proxy in C# with ImpromptuInterface, So now it's easy to create a proxy. h3. Example. Here's an interface you want to create a dynamic proxy for: interface IFoo { string DoStuff(int n); }. Step 1 I configure the client (browser) for all request to be send to 127.0.0.1 at the port the Proxy listen. This way, request will be not sent to the Internet directly but will be processed by the proxy. Step2 The proxy see a new connection, read the HTTP header and see the request he must executes. He executes the request.

How to do Dynamic Proxies in C#, You can use DynamicProxy to generate lightweight proxies on the fly for one or more interfaces or even concrete classes (but only virtual methods will be� Creating a dynamic proxy generator with c# – Part 2 – Interceptor Design Wednesday, March 24, 2010 .NET AOP ASP.NET ASP.NET MVC ASPECT ORIENTATED PROGRAMMING C# DEPENDENCY INJECTION DI DYNAMIC PROXY General Software Development INVERSION OF CONTROL IoC TDD

Take a look at PostSharp. I don't know of a way to do what you want in vanilla .Net, but PostSharp offers things like "OnMethodBoundaryAspect" which can be used to either replace or wrap the code inside the method.

I've used it to do things like logging, parameter validation, exception handling etc.

There is a free Community Edition, which should work for you. You'll need it installed on your development machine, as well as any build server that you use.

DynamicProxy, The class must have a public or protected parameter-less constructor. Let's create a simple dynamic proxy generator which accepts an interface type and as part of Setup. Posted on Sunday, April 4, 2010 3:41 PM C# | Back to top. Related� For adding any functionality before and after of every function in a class, Real proxy is a good approach. So now in T can be any TestClass. Create Instance like this for TestClass-var _instance=(object)DynamicProxy(TestClass).GetTransparentProxy(); The code for Dynamic Proxy-

Another option is ContextBoundObject.

There was an article on CodeProject about 8-9 years back using this approach to trace method calls.

A simple Dynamic Proxy, How to make a simple dynamic proxy in C#. c# .net reflection proxy aop. I want to build a dynamic proxy object to add certain functionality to an object. basically i� Castle Dynamic Proxy tutorial is a series of blogposts that talk in details about various parts of Castle DynamicProxy framework. So far the following parts have been published: This tutorial covers DynamicProxy version 2.2 As of now current version is 2.5 which has seen some changes.

How to make a simple dynamic proxy in C#, NET framework to create lightweight dynamic proxies. Reflection namespace) and an array of parameters; in the simplest case, it could simply call the method� What is a dynamic proxy? Let’s begin with a simple definition – a proxy acts as an interception mechanism to a class (or interface), in a transparent way and can allow the developer to intercept calls to the original class and add or change functionality on the original class.

mtamme/NProxy: NProxy is a library for the .NET framework , Simple, transparent, easy to understand, object proxy using DLR and ImpromptuInterface - curit/DynamicProxy.

curit/DynamicProxy: Simple, transparent, easy to , DynamicProxy to a more recent version and things have changed a little, Let's begin with a simple definition – a proxy acts as an interception�

Comments
  • have you looked at castleproject.org/dynamicproxy/index.html ?
  • @np-hard if you post this as an answer, i will accept it... not 100% what i was looking for, but good enough.
  • Do you know the type you want to proxy at compile time, or only at runtime?
  • @Sneal only at run time. probably I'll know it at compile time but i want to keep flexibility...
  • That definitely makes things a lot harder, as Castle DynamicProxy can only intercept virtual methods. I think you're stuck using the profiling api.
  • Could you say just a word about how ImpromptuInterface works under the hood? That is, what technique does ActLike use to create an object of any type? Some kind of byte code generation?
  • @Lii I didn't develop ImpromptuInterface. But it uses the DLR to dynamically bind to functions on the ducktyped object. And then it uses that same trick to cast it to the Interface you specify.
  • What's the performance impact of something like this? AFAIK .GetType() is not very performance friendly.
  • Yeah it's prolly a smart idea to examine the type on construction and drop all the functions in a dict. Ehhh I went for simplicity in my explanation not performance.
  • @FrankerZ if you look at the my project here: github.com/curit/DynamicProxy/blob/master/DynamicProxy/… you'll see I did it differently there. :)
  • No. But you can follow the links and find far better examples and explenations than anything I can write here.
  • Postsharp works at compile time for known types. I don't think is what OP needed