title: Where "user" comes from in convertAndSendToUser works in SockJS+Spring Websocket?
body: <p>I would like to understand how convertAndSendToUser works in Spring SockJS+Websocket framework.</p>
  
  <p>In client, we would connect as</p>
  
  <pre><code>stompClient.connect(login, password, callback())
  </code></pre>
  
  <p>which will result in connect request with "Stomp credentials" of login and password, that can be seen e.g. if we handle SessionConnectEvent <a href="http://www.sergialmar.com/2014/03/detect-websocket-connects-and-disconnects-in-spring-4/" rel="noreferrer">http://www.sergialmar.com/2014/03/detect-websocket-connects-and-disconnects-in-spring-4/</a></p>
  
  <p>But it remains unclear to me whether this will be the "user" meant in server-side send operation to a queue:</p>
  
  <pre><code> simpMessagingTemplate.convertAndSendToUser(username, "/queue/reply", message);
  </code></pre>
  
  <p>The closest I can get is to read this thread <a href="https://stackoverflow.com/questions/22367223/sending-message-to-specific-user-on-spring-websocket">Sending message to specific user on Spring Websocket</a>, answer by Thanh Nguyen Van, but it is still unclear.</p>
  
  <p>Basically what I need to do, is to subscribe some clients to same topic, but on server, send them different data. Client may supply user identifier. </p>