rttService = (RTTService) getServiceBroker().getService (this, RTTService.class, null);
  public void initialize ()   {    super.initialize();    rttService = (RTTService) getServiceBroker().getService (this, RTTService.class, null);    synchronized (MessageAckingAspect.class)    {      if (instance == null)      {        //  Kick off worker threads        messageResender = new MessageResender (this);        threadService().getThread (this, messageResender, "MessageResender").start();        pureAckSender = new PureAckSender (this);        threadService().getThread (this, pureAckSender, "PureAckSender").start();        pureAckAckSender = new PureAckAckSender (this);        threadService().getThread (this, pureAckAckSender, "PureAckAckSender").start();        instance = this;      }    }  }