如何使用ASP.NET Hosting在Nancy中使用SignalR将服务器与客户端通信？

Question

Most of the examples I've found for SignalR are assuming ASP.NET (MVC or not). I'm using NancyFX . I'm having just one problem, so I'm hoping there's something I'm overlooking or some thing I need to do in Nancy to compensate for not being ASP.NET.

My one goal is to be able to notify the client browsers when a server event happens. I don't plan on replacing my Nancy routes with hub methods. But I would like the ability to call into the browser from my routes (actions).

I have very simple Hub that I created following the example in the SignalR Wiki . I'm not even sure I need it, since I don't plan on calling client to server.

public interface IUserNotifier
{
    void Start();
    void Notify(object @event);
}

I used an interface in hopes that I would be able to inject the same hub later on to use in my nancy routes... I'm not sure that is in the cards.

[HubName("userNotifier")]
public class UserNotifier : Hub, IUserNotifier
{        
    public void Start()
    {
        Notify(new {Status = "Started"});
    }

    public void Notify(object @event)
    {
        Clients.notification(@event);
    }
}

When I have the following code in my html file, I can see that it executes the Start() method, and then the Notify() method, delivering content to my client.

var communicator = $.connection.userNotifier;

$.extend(communicator, {
    Notification: function(event) {
        alert("notification received from server!");
        console.log(event);
    }
});

$.connection.hub.start()
    .done(function() {
        communicator.start();
});

Like I said, "starting" the hub works and sends a notification to the client. Very cool. But, then, my primary goal hasn't been accomplished yet. I need to initiate these notifications from other places in my code where they might not be directly associated with a "request".

I tried injecting my IUserNotifier in my nancy modules for use in the routes, but when the Notify() is fired, I get:

That's because the Clients property on the Hub base class is null (hasn't been initialized). So, I switched gears. I tried to follow multiple examples, including the example from the wiki page about hubs in the section called "Broadcasting over a Hub from outside of a Hub":

public class NotifierModule : NancyModule
{
    public NotifierModule(){

        Get["/notify/{message}"] = p => { 
            var context = GlobalHost.ConnectionManager.GetHubContext<UserNotifier>();
            context.Clients.notification(new { Message = p.message });
        };
    }
}

My Nancy route executes without throwing errors. Except my browser never receives the message. If I set a breakpoint in the route, I can see that Clients is initialized. Maybe the collection of clients is initialized but empty. Who knows? Maybe you do. :)

Again, my main goal is to be able to send events/notifications to the browser from anywhere in my code, any time. Is that too much to ask? What should I be doing here?

Answer 1

I'm sure you must have found the answer already. However, I figured I could try and help out in case anyone else runs into a similar problem. In order for your server on the .NET side to send messages to clients, it would also need to have a connection made to the hub.

var connection = new HubConnection("http://localhost/");
connection.Start();
connection.Notify("Hello");

Check out an official example at:

https://github.com/SignalR/SignalR/blob/master/samples/Microsoft.AspNet.SignalR.Client.Samples/Program.cs