Handling multiple requests with C# HttpListener

Question

I have a .NET Windows Service which spawns a thread that basically just acts as an HttpListener. This is working fine in synchronous mode example...

private void CreateLListener()
{
    HttpListenerContext context = null;
    HttpListener listener = new HttpListener();
    bool listen = true;

    while(listen)
    {
        try
        {
            context = listener.GetContext();
        }
        catch (...)
        {
            listen = false;
        }
        // process request and make response
    }
}

The problem I now have is I need this to work with multiple requests and have them responded to simultaneously or at least in an overlapped way.

To explain further - the client is a media player app which starts by making a request for a media file with the request header property Range bytes=0-. As far as I can tell it does this to work out what the media container is.

After it has read a 'chunk' (or if it has read enough to ascertain media type) it then makes another request (from a different client socket number) with Range bytes=X-Y. In this case Y is the Content-Length returned in the first response and X is 250000 bytes less than that (discovered using IIS as a test). At this stage it is getting the last 'chunk' to see if it can get a media time-stamp to gauge length.

Having read that, it makes another request with Range bytes=0- (from another socket number) to start streaming the media file properly.

At any time though, if the user of the client performs a 'skip' operation it then sends another request (from yet another socket number) with Range bytes=Z- where Z is the position to jump to in the media file.

I'm not very good with HTTP stuff but as far as I can tell I need to use multiple threads to handle each request/response while allowing the original HttpListener to return to listening. I've done plenty of searching but can't find a model which seems to fit.

EDIT:

Acknowledgement and gratitude to Rick Strahl for the following example which I was able to adapt to suit my needs...

Add a Web Server to your .NET 2.0 app with a few lines of code

Answer 1

If you need a more simple alternative to BeginGetContext, you can merely queue jobs in ThreadPool, instead of executing them on the main thread. Like such:

private void CreateLListener() {
    //....
    while(true) {
        ThreadPool.QueueUserWorkItem(Process, listener.GetContext());    
    }
}
void Process(object o) {
    var context = o as HttpListenerContext;
    // process request and make response
}

Answer 2

If you're here from the future and trying to handle multiple concurrent requests with a single thread using async/await..

public async Task Listen(string prefix, int maxConcurrentRequests, CancellationToken token)
{
    HttpListener listener = new HttpListener();
    listener.Prefixes.Add(prefix);
    listener.Start();

    var requests = new HashSet<Task>();
    for(int i=0; i < maxConcurrentRequests; i++)
        requests.Add(listener.GetContextAsync());

    while (!token.IsCancellationRequested)
    {
        Task t = await Task.WhenAny(requests);
        requests.Remove(t);

        if (t is Task<HttpListenerContext>)
        {
            var context = (t as Task<HttpListenerContext>).Result;
            requests.Add(ProcessRequestAsync(context));
            requests.Add(listener.GetContextAsync());
        }
    }
}

public async Task ProcessRequestAsync(HttpListenerContext context)
{
    ...do stuff...
}