How to use SignalR hub instance outside of the hub

问题:

I am using SignalR to broadcast messages to all my clients. I need to trigger the broadcasting outside of my hub class i.e. something like below:

var broadcast = new chatHub(); broadcast.Send("Admin","stop the chat");

I am getting error message as:

Using a Hub instance not created by the HubPipeline is unsupported.

回答1:

You need to use GetHubContext:

var context = GlobalHost.ConnectionManager.GetHubContext<chatHub>();
context.Clients.All.Send("Admin", "stop the chat");

This is described in more detail at http://www.asp.net/signalr/overview/signalr-20/hubs-api/hubs-api-guide-server#callfromoutsidehub.

回答2:

A small update for those who might be wondering where the GlobalHost has gone. SignalR has been completely rewritten for .net core. So if you are using the SignalR.Core package (Difference between SignalR versions), you get an instance of SignalR hub context by injecting it into your service:

public class MyNeedyService
{
    private readonly IHubContext<MyHub> ctx;

    public MyNeedyService(IHubContext<MyHub> ctx)
    {
        this.ctx = ctx;
    }

    public async Task MyMethod()
    {
        await this.ctx.All.SendAsync("clientCall");
    }
}

And in Startup.cs:

services.AddSignalR()/*.AddAzureSignalR("...")*/;

Microsoft docu is here: Send SignalR messages from outside the hub.