It is simple to send an special message type from server to some group of Clients in SignalR using:

 Client.Groups("Developers").SendAsync("Notification",new {Message="New Notification Arrived from ...."});

And Also it is not hard to send an stream from server to client. But it should pulled from client side as:

hubConnection.stream("CounterStream").subscribe({next:f1,complete:f2,error:f3})

Now I want to send an stream from server to group of user. A simple answer is to first send a notification to group of user and then they subscribe to stream but as you may know it is not very performant since the stream should be prepared for each client in server. How we can push the stream once from server to client and user invoke it?