title: How to use HubConnectionBuilder to communicate with javascript clients once the HubConnection is disposed
body: <p>I'm trying to use the BubConnectionBuilder with my SignalR implementation in order to recreate a hub instance from a background service on the server to contact a client once a process is completed at the server.  </p>
  
  <p>Since the HubConnection is short lived, my Hub Clients is disposed when I try to go back and communicate with the client, so I'm trying to use the HubConnectionBuilder to re-create a hub to send the message (I retain the connection id with the task)</p>
  
  <p>The .Net client documentation states that you use .WithUrl('') to specify the hub url, but the SignalR .Net Core client library off nuget doesn't have that, it only has a services collection.  Is there any documentation or examples of the nuget package in use?</p>