public Heartbeat(MBeanServer agent,
    ObjectName timer,
    long interval) 
{
      this.agent = agent;
      this.timer = timer;
      this.interval = interval;
}

CTOR *

 public  void start() throws Exception 
{
      // Get the heartbeat period in mSecs
      long period = interval * 1000;
      if (period < = 0) {
         log.debug("Heartbeat disabled");
         return;
      }
      // Skip if schedule is already set
      //
      if(heartbeatSchedule == null) {
         try {
            // Organise schedulled emission of heartbeat notification
            Object userData = null;                 // No user payload
            Date startTime = new Date();            // Start immediately
            Long nbOccurences = new Long(0);        // Go on forever 
            // If timer MBean not registered, exception will be thrown
            heartbeatSchedule = (Integer) agent.invoke(
               timer,
               "addNotification",
               new Object[] { 
                  EventTypes.HEARTBEAT, 
                  NOTIFICATION_MSG,
                  userData,
                  startTime,
                  new Long(period),
                  nbOccurences
               },
               new String[] {
                  "java.lang.String",
                  "java.lang.String",
                  Object.class.getName(),
                  Date.class.getName(),
                  Long.TYPE.getName(),
                  Long.TYPE.getName()
               });
            log.debug("Heartbeat period set to " + period + " msecs");                
         }
         catch (Exception e) {
            log.error("while setting heartbeat notification", e);
            throw e;
         }
      }
}

Setup the production of heart-beat notifications

 public  void stop() throws Exception 
{
      if(heartbeatSchedule != null) {
         try {
            // Have the schedule removed
            agent.invoke(
               timer, 
               "removeNotification", 
               new Object[] { heartbeatSchedule },
               new String[] { heartbeatSchedule.getClass().getName() }
            );
            heartbeatSchedule = null;
         }        
         catch (Exception e) {
            log.error("while unsetting heartbeat notification", e);
            throw e;
         }
      }
}

Disable heartbeat *