Asp.net-mvc – SignalR + posting a message to a Hub via an action method

actionasp.net-mvcmessagesignalrsignalr-hub

I am using the hub- feature of SignalR (https://github.com/SignalR/SignalR) to publish messages to all subscribed clients:

public class NewsFeedHub : Hub
public void Send(string channel, string content)
{
    Clients[channel].addMessage(content);
}

This works fine when calling "Send" via Javascript, but I would also like the web application to publish messages (from within an ASP.NET MVC action method). I already tried instantiating a new object ob NewsFeedHub and calling the Send method, but this results in an error (as the underlying "Connection" of the Hub is not set). Is there a way to use the Hub without a connection?

Best Answer

Please note that the SignalR API has changed multiple times since this question was asked. There is a chance that some answers will become out of date. This does not mean that they should be down-voted as they were correct at the time of writing

There is another updated answer for this, as seen in the SignalR Wiki

Public ActionResult MyControllerMethod()
{
    var context = GlobalHost.ConnectionManager.GetHubContext<MyHub>();
    context.Clients.All.methodInJavascript("hello world");
    // or
    context.Clients.Group("groupname").methodInJavascript("hello world");
}

vb.net

Public Function MyControllerMethod() As ActionResult
    Dim context = GlobalHost.ConnectionManager.GetHubContext(Of MyHub)()
    context.Clients.All.methodInJavascript("hello world")
    '' or
    context.Clients.Group("groupname").methodInJavascript("hello world")
End Function

Update

This code has been updated. Follow http://www.asp.net/signalr/overview/signalr-20/hubs-api/hubs-api-guide-server for changes.

If you are using DI container

If you are using a DI container to wire up your hubs, get IConnectionManager from your container, and call GetHubContext on that connectionManager.

Related Solutions

C# – Send signalr message from server to all clients

You can do this by using a static method:

SignalR v.04-

public class MyHub : Hub
{
    internal static void SendMessage(string message)
    {
        var connectionManager = (IConnectionManager)AspNetHost.DependencyResolver.GetService(typeof(IConnectionManager));
        dynamic allClients = connectionManager.GetClients<MyHub>();
        allClients.messageRecieved(message);
    }

    ...
}

SignalR 0.5+

public class MyHub : Hub
{
    internal static void SendMessage(string message)
    {
        IHubContext context = GlobalHost.ConnectionManager.GetHubContext<MyHub>();
        context.Clients.messageRecieved(message);
    }

    ...
}

You can then call this like so:

MyHub.SendMessage("The Message!");

Good article on the SignalR API: http://weblogs.asp.net/davidfowler/archive/2012/05/04/api-improvements-made-in-signalr-0-5.aspx

Provided by Paolo Moretti in comments

C# – SignalR send message to single connectionId

Well, you can send a message to a single client from a Hub like so:

Clients.Client(someConnectionIdIWantToSendToSpecifically).doSomething();

The trick is you need to know the connection ID you want to send the message to. Even more specifically you probably want to know the logical identity of the thing you want to send the message too since that logical identity could have multiple connections or have dropped and reconnected under a completely different connection id. Mapping of connections to logical identities is something SignalR leaves up to the application itself.

Best Answer

Related Solutions

C# – Send signalr message from server to all clients

C# – SignalR send message to single connectionId

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