Call AddEventNotifier when you want the database to automatically register and unregister an interest in server events when it opens and closes a connection to the server.  

Notifier is the interface to an object that has in interest in a set of events on the InterBase server. For example, Notifier can be the interface to a TIBEvents object. 

AddEventNotifier adds Notifier to its internal list of event notifiers. When TIBDataBase opens a connection, it checks every notifier in its list, and if a notifier indicates that it wants to be auto-registered, AddEventNotifier calls its RegisterEvents method so that the notifier registers its interest with the InterBase Event manager. Before TIBDataBase closes a connection, it unregisters interest from every notifier in its list.