@Override
    public void start() throws IllegalStateException {
        super.start();
        // Use component manager for Presence Updates.
        componentManager = InternalComponentManager.getInstance();
        // Listen for user deletion events
        UserEventDispatcher.addListener(this);

    }
Simple in memory implementation of the PresenceManager interface.

@author Iain Shigeoka
xmppserver/src/main/java/org/jivesoftware/openfire/spi/PresenceManagerImpl.java