Startup.Owin.cs

public partial class Startup
{
    /// <summary>
    /// This hax is necessary for signalr2 to work
    /// </summary>
    private void HackInWebsockets(IAppBuilder app)
    {
        app.Use((c, n) =>
        {
            c.Environment.Add("server.Capabilities", new Dictionary<string, object>
            {
                { "websocket.Version", "1.0" }
            });

            var accept = c.Get<Action<IDictionary<string, object>, Func<IDictionary<string, object>, Task>>>("websocket.Accept");
            if (accept != null)
            {
                c.Set<Action<IDictionary<string, object>, Func<IDictionary<string, object>, Task>>>("websocket.Accept", (_, hcb) =>
                {
                    accept(_, aenv =>
                    {
                        aenv.Add(typeof(WebSocketContext).FullName, new HackedWebSocketContext((WebSocket)aenv[typeof(WebSocket).FullName]));
                        return hcb(aenv);
                    });
                });
            }

            return n();
        });
    }

    private class HackedWebSocketContext : WebSocketContext
    {
        private readonly WebSocket webSocket;

        public override Uri RequestUri => throw new NotImplementedException();

        public override NameValueCollection Headers => throw new NotImplementedException();

        public override string Origin => throw new NotImplementedException();

        public override IEnumerable<string> SecWebSocketProtocols => throw new NotImplementedException();

        public override string SecWebSocketVersion => throw new NotImplementedException();

        public override string SecWebSocketKey => throw new NotImplementedException();

        public override CookieCollection CookieCollection => throw new NotImplementedException();

        public override IPrincipal User => throw new NotImplementedException();

        public override bool IsAuthenticated => throw new NotImplementedException();

        public override bool IsLocal => throw new NotImplementedException();

        public override bool IsSecureConnection => throw new NotImplementedException();

        public override WebSocket WebSocket => webSocket;

        public HackedWebSocketContext(WebSocket webSocket)
        {
            this.webSocket = webSocket;
        }
    }
}