Node.cs

No, the title is not a typo. There is so much noise around Node.js, I thought it would be fun to make a sample of how it would work in C# using the TPL. Here is how the hello world sample would look like:

public class HelloHandler : AbstractAsyncHandler
{
    protected override Task ProcessRequestAsync(HttpContext context)
    {
        context.Response.ContentType = "text/plain";
        return context.Response.Output.WriteAsync("Hello World!");
    }
}

And the code to make this happen:

public abstract class AbstractAsyncHandler : IHttpAsyncHandler
{
    protected abstract Task ProcessRequestAsync(HttpContext context);

    private Task ProcessRequestAsync(HttpContext context, AsyncCallback cb)
    {
        return ProcessRequestAsync(context)
            .ContinueWith(task => cb(task));
    }

    public void ProcessRequest(HttpContext context)
    {
        ProcessRequestAsync(context).Wait();
    }

    public bool IsReusable
    {
        get { return true; }
    }

    public IAsyncResult BeginProcessRequest(HttpContext context, AsyncCallback cb, object extraData)
    {
        return ProcessRequestAsync(context, cb);
    }

    public void EndProcessRequest(IAsyncResult result)
    {
        if (result == null)
            return;
        ((Task)result).Dispose();
    }
}

And you are pretty much done. I combined this with a HttpHandlerFactory which does the routing, and you get fully async, and quite beautiful code.