Calling SignalR hub clients from elsewhere in system

Question

I've set up a SignalR hub to communicate between the server and client. The hub server side code is stored in a class called Hooking.cs. What I want is to be able to call a method defined in Hooking.cs to allow me to broadcast messages to any connected clients from anywhere in my application. It seems that a new instance of Hooking.cs is created for every client/server call, so I had hoped that I would be able to use something like

var hooking = new Hooking();
hooking.Test();

with the method Test() defined in Hooking.cs such as

public static void Test() {
    Clients.test()
}

and with a the client side javascript

var hooking = $.connection.hooking;
hooking.test = function() { alert("test worked"); };
$.connection.hub.start()

Unfortunately it isn't that simple, as Clients is not static, so not accessible from a static method.

Looking through the SignalR source code I came across a method that looked promising, Hubs.Invoke(string hubName, string method, params object[] args), so I would hope I could use something such as Hubs.Invoke("Hooking", "Test") but I can't make it work.

Any help with this would be hugely appreciated

But maybe you can help me ;) Any idea how to perform your js code in your broadcast message for all other clients, and not the originating caller who issued the message? :) — GONeale, Oct 03 '11 at 11:27
Unfortunately I don't. I've been handling this client side, sending the client id back with the response, and simply not calling the function if the id's match — Jordan Wallwork, Oct 03 '11 at 12:06

Paolo Moretti · Answer 1 · 2014-10-07T11:24:08.073

111

This is the correct way for SignalR 2.x:

var context = GlobalHost.ConnectionManager.GetHubContext<MyHub>();
context.Clients.All.addMessage(message);

Basically, you can use the dependency resolver for the current host to resolve the IConnectionManager interface which allows you to get ahold of the context object for a hub.

Further information can be found in the official documentation.

edited Oct 07 '14 at 11:24

answered Jun 06 '12 at 12:54

Paolo Moretti

47,973
21
95
89

score 23 · Answer 2 · answered Feb 07 '12 at 17:26

23

Hub.GetClients has disappeared in version 0.4.0.

From the wiki you can now use:

IConnectionManager connectionManager = AspNetHost.DependencyResolver.Resolve<IConnectionManager>();
dynamic clients = connectionManager.GetClients<MyHub>();

answered Feb 07 '12 at 17:26

Greg Ennis

13,126
1
64
70

7

And don't forget to add `using SignalR.Infrastructure;` – nmat Feb 13 '12 at 17:14

score 6 · Answer 3 · answered Jan 06 '17 at 07:03

You can easily use a hub by following this 2 step-

Instantiating by dependency injection like this-

public class ClassName
{
    ........
    ........
    private IHubContext _hub;

    public BulletinSenderController(IConnectionManager connectionManager)
    {
        _hub = connectionManager.GetHubContext<McpHub>();
        ........
        ........
    }

    ............
    ............
}

2.Using the hub object like this-

_hub.Clients.All.onBulletinSent(bulletinToSend);

More can be found here.

Example code can be found in this git repo.

score 1 · Answer 4 · answered Sep 20 '19 at 12:04

This has changed in .NET Core 2, now you can use dependency injection like this:

    private readonly IHubContext<MyHub,IMyHubInterface> _hubContext;

    public MyController(MyHub,IMyHubInterface hubContext)
    {
        _hubContext = hubContext;
    }

    public bool SendViaSignalR()
    {
        _hubContext.Clients.All.MyClientSideSignalRMethod(new MyModel());
        return true;
    }

score 1 · Answer 5 · answered Oct 03 '11 at 11:24

1

Have a look at how it's done in Chat.cs in SignalR.Samples.Hubs.Chat from https://github.com/SignalR/SignalR.

I can see in there that static Dictionary<TKey, TValue>'s are being instantiated at the top, so I imagine they are being maintained persistently too, either with the Chat class being a persisted instance (?) or that array being updated somehow.

Check it out, David Fowler would probably be the best on this.

answered Oct 03 '11 at 11:24

GONeale

25,353
21
101
146

Yeah I'm using the SignalR samples to try and work this out. The dictionaries are static, so the information persists over multiple instances of the class, that's why I'd hoped I could simply create an instance of Hooking.cs and use that, but it doesn't work – Jordan Wallwork Oct 03 '11 at 12:04

Calling SignalR hub clients from elsewhere in system

5 Answers5

Linked