#owin single #http request listener.

SingleRequestListener.cs

using Microsoft.Owin;
using Microsoft.Owin.Hosting;
using Owin;
using System;
using System.Threading.Tasks;

/* Used NuGet Packages
   install-package Microsoft.Owin
   install-package Microsoft.Owin.Host.HttpListener
   install-package Microsoft.Owin.Hosting
   install-package Owin
 */

public class SingleRequestListener : IDisposable
{
    private readonly string url;
    private readonly TaskCompletionSource<IOwinRequest> completionSource;

    private IDisposable webApp;

    public SingleRequestListener(string url)
    {
        this.url = url;
        completionSource = new TaskCompletionSource<IOwinRequest>();
    }

    public Task<IOwinRequest> ListenRequest()
    {
        CheckDisposed();

        var startOptions = new StartOptions();
        startOptions.Urls.Add(url);
        webApp = WebApp.Start(startOptions, app => app.Run(HandleRequest));
        Console.WriteLine("Waiting");
        return completionSource.Task;
    }

    public static Task<IOwinRequest> ListenRequest(string url)
    {
        return new SingleRequestListener(url).ListenRequest();
    }

    private bool handled = false;
    private readonly object lockHandled = new object();
    private async Task HandleRequest(IOwinContext ctx)
    {
        lock (lockHandled)
        {
            if (handled) return;
            handled = true;
        }

        await Task.Yield();
        completionSource.SetResult(ctx.Request);
        Dispose();
    }
    private void CheckDisposed()
    {
        if (disposed)
            throw new ObjectDisposedException(GetType().FullName);
    }

    private bool disposed = false;
    public void Dispose()
    {
        if (webApp != null)
        {
            webApp.Dispose();
            disposed = true;
        }
    }
}