question: public void registerCallbackHandler ( SMSObjectListener changeListener ) throws SMSException { objectListener = changeListener ; if ( ! notificationInitialized ) { String notificationFlag = SystemProperties . get ( NOTIFICATION_PROPERTY , "true" ) ; if ( notificationFlag . equalsIgnoreCase ( "true" ) ) { try { URL url = WebtopNaming . getNotificationURL ( ) ; PLLClient . addNotificationHandler ( JAXRPCUtil . SMS_SERVICE , new SMSNotificationHandler ( ) ) ; client . send ( "registerNotificationURL" , url . toString ( ) , null , null ) ; if ( debug . messageEnabled ( ) ) { debug . message ( "SMSJAXRPCObject: Using " + "notification mechanism for cache updates: " + url ) ; } } catch ( Exception e ) { if ( debug . warningEnabled ( ) ) { debug . warning ( "SMSJAXRPCObject: Registering for " + "notification via URL failed: " + e . getMessage ( ) + "\nUsing polling mechanism for updates" ) ; } startPollingThreadIfEnabled ( getCachePollingInterval ( ) ) ; } } else { startPollingThreadIfEnabled ( getCachePollingInterval ( ) ) ; } notificationInitialized = true ; } }
target:  Registration for event change notifications. Only SMSNotificationManager would be calling this method to register itself