// run poller on a separate thread
        _poller = new NetMQPoller { _dealer, _subscriber, _outgoingMessageQueue, _subscriptionChanges};
        _poller.RunAsync();
        // run a monitor listening for Connected and Disconnected events
        _monitor = new NetMQMonitor(_dealer, "inproc://rep.inproc", SocketEvents.Disconnected | SocketEvents.Connected);
        _monitor.EventReceived += _monitor_EventReceived;
        _monitor.StartAsync();

    [Fact]
    public void Monitoring()
        var listeningEvent = new ManualResetEvent(false);
        var acceptedEvent = new ManualResetEvent(false);
        var connectedEvent = new ManualResetEvent(false);
        using (var rep = new ResponseSocket())
        using (var req = new RequestSocket())
        using (var poller = new NetMQPoller())
        using (var repMonitor = new NetMQMonitor(rep, "inproc://rep.inproc", SocketEvents.Accepted | SocketEvents.Listening))
        using (var reqMonitor = new NetMQMonitor(req, "inproc://req.inproc", SocketEvents.Connected))
            repMonitor.Accepted += (s, e) => acceptedEvent.Set();
            repMonitor.Listening += (s, e) => listeningEvent.Set();
            repMonitor.AttachToPoller(poller);
            int port = rep.BindRandomPort("tcp://127.0.0.1");
            reqMonitor.Connected += (s, e) => connectedEvent.Set();
            reqMonitor.AttachToPoller(poller);
            poller.RunAsync();
            req.Connect("tcp://127.0.0.1:" + port);
            req.SendFrame("a");
            rep.SkipFrame();
            rep.SendFrame("b");
            req.SkipFrame();