SignalR - long running task on start

Question

I'm looking into starting a long running task when SignalR starts and then sending data from it to the client.

From what I could find the place to run code on startup is inside Startup.Configure(IApplicationBuilder app, IHostingEnvironment env) method.

When using ASP.NET SignalR I can then send messages to frontend using:

var context = GlobalHost.ConnectionManager.GetHubContext<ChatHub>();
context.Clients.All.Send("Admin", "message");

In ASP.NET Core SignalR the same is achieved by injecting an IHubContext see . But I can't use that in the Configure method since it is not possible to inject anything into it.

Where can I inject IHubContext in a method which is called when SignalR starts so I can start the long running task?

Answer 1

I think the best approach is using a hosted-service . You could do something like this:

internal class MySignalRService : IHostedService, IDisposable
{
    private readonly IHubContext _hubContext;

    public MySignalRService(IHubContext hubContext)
    {
        _hubContext = hubContext;
    }

    public Task StartAsync(CancellationToken cancellationToken)
    {
        //Setup some scheduler to do your job

        return Task.CompletedTask;
    }

    public Task StopAsync(CancellationToken cancellationToken)
    {
    }

    public void Dispose()
    {
    }
}

And then

services.AddHostedService<MySignalRService>();