Reactive Extensions Web Server

Just out of personal interest, I decided to try to write a basic web server using Reactive Extensions (aka Rx). Almost immediately, I came up against the following problem:

HttpListener's async pattern doesn't match the normal async pattern signature, the EndGetContext returns a HttpListenerContext instead of an IAsyncResult!

So my question is: is there a way around this?

Here's some code - the compiler (r开发者_C百科ightly) complains about the second argument to Observable.FromAsyncPattern:

Update - As Jon rightly pointed out, it wasn't the pattern, it's complaining that I haven't provided the return type - this works:

var observable = Observable.FromAsyncPattern<HttpListenerContext>(listener.BeginGetContext, listener.EndGetContext);

The original code:

using System;
using System.Net;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace RxWebTest
{
    class Program
    {
        static void Main(string[] args)
        {
            HttpListener listener = new HttpListener();
            try
            {
                listener.Start();

                var observable = Observable.FromAsyncPattern(listener.BeginGetContext, listener.EndGetContext);



                Console.ReadLine();
            }
            finally
            {
                listener.Abort();
            }
        }
    }
}

That is the normal pattern. It's BeginGetContext which returns IAsyncResult; EndGetContext takes an IAsyncResult and returns the result of the asynchronous operation - the context. That's exactly the same as (say) Stream.BeginRead/EndRead, where EndRead returns an int, the number of bytes read.

What happens when you try the code you've posted? I can't immediately see why it wouldn't work.

The trick to figuring out the template parameters for FromAsyncPattern, is to imagine you're creating a Func that is matching the synchronous version of the function.

In this case, the prototype is:

public HttpListenerContext GetContext()

Which means, my Func would look like:

Func<HttpListenerContext>

Then, just take your template parameter and copy-paste it to the FromAsyncPattern.