2 Replies Latest reply: Feb 11, 2012 1:52 PM by fvitorc RSS

    Best way to detect user presence

    fvitorc Newbie

      Hi,

       

      I am trying to find the best way to detect user presence (or queue presence).

      I've been looking at the source code for sometime now, and I think that one way to know when a user has connected is to listen to the FinishStateSync command on the ServerBus. Am I correct? Is there a better way for that?

       

      As for the disconnect I haven't find anything.

       

      I know that I could send Connected and Disconnected messages from the client, but I would not like to rely on these methods. For example, if the browser crashes, I would never know that the user has disconnected, because he didn't even had the chance to send the Disconnected message.

       

      Regards,

      Vitor.

        • 1. Re: Best way to detect user presence
          fvitorc Newbie

          Actually, it's not possible to listen to incoming messages on the ServerBus. I get the following exception if I try to do so:

           

          java.lang.IllegalArgumentException: cannot modify or subscribe to reserved service: ServerBus

           

           

          So I would like to request a new feature for errai. The proposal would be to get queue connect/disconnect events.

          The end user could write something like that to get these events:

           

          @QueuePresence

          public class MyQueuePresence implements QueuePresenceListener {

           

              @Override

               public void onConnect(String sessionId) {

                   // do whatever I want

              }

           

              @Override

              public void onDisconnect(String sessionId) {

                  // do whatever I want

              }

           

          }

           

          Of course, the interface, annotation and methods names could be different.

          Where can I request such feature? Is it writing in this forum enough?

           

          Regards,

          Vitor.

          • 2. Re: Best way to detect user presence
            fvitorc Newbie

            After a while, I found a solution for that. For disconnects it's quite simple, but for connects you must disable the monitor tool.

             

            Anyway, the ServerMessageBusImpl (just cast to it from a MessageBus) has a addQueueClosedListener for disconnects.

             

            It also has a attachMonitor method, which provides not only connect/disconnect events, but a lot of other notifications.

            The bad part is that you won't be able to use the monitor tool, because only one monitor can be active at a time.

             

            I believe the best thing to do then, is to initially send your own connect message (do not rely on ServerBus), and use a QueueClosedListener for disconnects.

             

            Regards,

            Vitor.