Adding signalr support to an ASP.NET core server

1. Add the Signalr service:

    
    services.AddSignalR();

2. Create a hub:

public class MyHub: Hub {

    public override Task OnConnectedAsync()  {
        /* Save somewhere the connection id based on authentication */
    }
    public override Task OnDisconnectedAsync() {
        /* ... */
    }

}

Keep in mind that the hub instance is created per connection. Whenever a client reconnects a new hub instance is created. That is the reason why it is better to keep separately a map of the user -> connection id.

3. Add the middleware as an endpoint option:

app.UseEndpoints(endpoints =>
            {
                /* Other endpoints */
                endpoints.MapHub<MyHub>("/myhub");
            });

This part automatically registers the /signalr endpoint.

4. An example for .NET client:

var connection = new HubConnectionBuilder()
                .WithUrl("https://localhost:44354/myhub")
                .WithAutomaticReconnect()
                .Build();

try {
       connection.StartAsync().Wait();
}
catch (Exception e)
{
    Console.WriteLine(e.ToString());
}