protected void sendServiceParcelAcknowledge(String messageID, int index) {
    Message msg = mServiceHandler.obtainMessage(MessageUtil.ID_PARCEL_ACKNOWLEDGMENT);
    msg.replyTo = serviceMessenger;
    msg.arg1 = index;

    try {
      debug("sending IPC parcel acknowledge: " + messageID + ", " + index);
      if (messageID != null) msg.obj = MessageUtil.setParcelableMessage(messageID);
      engineMessenger.send(msg);
    } catch (Exception x) {
      debug("sendIPCEvent " + x.getClass().getSimpleName() + ", " + x.getMessage());
    }
  }