JBoss Cache users can register a listener to receive cache events described earlier in the User API chapter. Users can alternatively utilize the cache's management information infrastructure to receive these events via JMX notifications. Cache events are accessible as notifications by registering a NotificationListener for the CacheJmxWrapper .

See the section in the JMX Reference chapter pertaining to JMX notifications for a list of notifications that can be received through the CacheJmxWrapper .

The following is an example of how to programmatically receive cache notifications when running in a JBoss AS environment. In this example, the client uses a filter to specify which events are of interest.

   MyListener listener = new MyListener();

   NotificationFilterSupport filter = null;



   // get reference to MBean server

   Context ic = new InitialContext();

   MBeanServerConnection server = (MBeanServerConnection)ic.lookup("jmx/invoker/RMIAdaptor");



   // get reference to CacheMgmtInterceptor MBean

   String cache_service = "jboss.cache:service=TomcatClusteringCache";

   ObjectName mgmt_name = new ObjectName(cache_service);



   // configure a filter to only receive node created and removed events

   filter = new NotificationFilterSupport();

   filter.disableAllTypes();

   filter.enableType(CacheNotificationBroadcaster.NOTIF_NODE_CREATED);

   filter.enableType(CacheNotificationBroadcaster.NOTIF_NODE_REMOVED);



   // register the listener with a filter

   // leave the filter null to receive all cache events

   server.addNotificationListener(mgmt_name, listener, filter, null);



   // ...



   // on completion of processing, unregister the listener

   server.removeNotificationListener(mgmt_name, listener, filter, null);

         

The following is the simple notification listener implementation used in the previous example.

   private class MyListener implements NotificationListener, Serializable

   {

      public void handleNotification(Notification notification, Object handback)

      {

         String message = notification.getMessage();

         String type = notification.getType();

         Object userData = notification.getUserData();



         System.out.println(type + ": " + message);



         if (userData == null)

         {

            System.out.println("notification data is null");

         }

         else if (userData instanceof String)

         {

            System.out.println("notification data: " + (String) userData);

         }

         else if (userData instanceof Object[])

         {

            Object[] ud = (Object[]) userData;

            for (Object data : ud)

            {

               System.out.println("notification data: " + data.toString());

            }

         }

         else

         {

            System.out.println("notification data class: " + userData.getClass().getName());

         }

      }

   }

         

Note that the JBoss Cache management implementation only listens to cache events after a client registers to receive MBean notifications. As soon as no clients are registered for notifications, the MBean will remove itself as a cache listener.