public void receiveMessage()
      throws IOException
      {
      DatagramPacket packet = new DatagramPacket (payload, payload.length);
      mailbox.receive (packet);
      SocketAddress clientAddress = packet.getSocketAddress();
      ViewProxy proxy = proxyMap.get (clientAddress);
      if (proxy == null)
         {
         proxy = new ViewProxy (mailbox, clientAddress);
         proxy.setViewListener (sessionManager);
         proxyMap.put (clientAddress, proxy);
         }
      if (proxy.process (packet)) // Returns true to discard view proxy
         {
         proxyMap.remove (clientAddress);
         }
      }