code: public void eventReceived (DEvent event)
      {
          if (event instanceof InvocationResponseEvent) {
              InvocationResponseEvent ire = (InvocationResponseEvent)event;
              handleInvocationResponse(ire.getRequestId(), ire.getMethodId(), ire.getArgs());
  
          } else if (event instanceof InvocationNotificationEvent) {
              InvocationNotificationEvent ine = (InvocationNotificationEvent)event;
              handleInvocationNotification(ine.getReceiverId(), ine.getMethodId(), ine.getArgs());
  
          } else if (event instanceof MessageEvent) {
              MessageEvent mevt = (MessageEvent)event;
              if (mevt.getName().equals(ClientObject.CLOBJ_CHANGED)) {
                  handleClientObjectChanged(((Integer)mevt.getArgs()[0]).intValue());
              }
          }
      }
docs: Process notification and response events arriving on user object.