A sample implementation of using Rx.NET on top of a C# HttpListener

ReactiveServer.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Reactive.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace Tests
{
  public class ReactiveServer : IObservable<HttpListenerContext>, IDisposable
  {
    private readonly IObservable<HttpListenerContext> _observable;
    private readonly CancellationTokenSource _cancelTokenSource;

    public ReactiveServer(IEnumerable<string> prefixes)
    {
      _cancelTokenSource = new CancellationTokenSource();

      _observable = Observable.Create<HttpListenerContext>(async observer =>
        {
          var server = new HttpListener();
          prefixes.ForEach(server.Prefixes.Add);
          server.Start();

          while (!_cancelTokenSource.IsCancellationRequested)
          {
            var context = await Task.Run(() => server.GetContext(), _cancelTokenSource.Token);
            observer.OnNext(context);
          }
        });
    }

    public void Dispose()
    {
      if (!_cancelTokenSource.IsCancellationRequested)
        _cancelTokenSource.Cancel();
    }


    public IDisposable Subscribe(IObserver<HttpListenerContext> observer)
    {
      return _observable.Subscribe(observer);
    }
  }
}