title: Send server message to connected clients with Signalr/PersistentConnection
body: <p>I´m using SignalR/PersistentConnection, not the Hub.</p>
  
  <p>I want to send a message from the server to client. I have the client id to send it, but how can I send a message from server to the client?</p>
  
  <p>Like, when some event happens on server, we want send a notification to a particular user.</p>
  
  <p>Any ideas?</p>