It is often useful for the application to react to certain events that occur inside Hibernate. This allows implementation of certain kinds of generic functionality, and extension of Hibernate functionality. The Interceptor interface provides callbacks from the session to the application allowing the application to inspect and/or manipulate properties of a persistent object before it is saved, updated, deleted or loaded. One possible use for this is to track auditing information. For example, the following Interceptor automatically sets the createTimestamp when an Auditable is created and updates the lastUpdateTimestamp property when an Auditable is updated. You may either implement Interceptor directly or (better) extend EmptyInterceptor. The interceptor would be specified when a session is created. You may also set an interceptor on a global level, using the Configuration. In this case, the interceptor must be threadsafe. If you have to react to particular events in your persistence layer, you may also use the Hibernate3 event architecture. The event system can be used in addition or as a replacement for interceptors. Essentially all of the methods of the Session interface correlate to an event. You have a LoadEvent, a FlushEvent, etc (consult the XML configuration-file DTD or the org.hibernate.event package for the full list of defined event types). When a request is made of one of these methods, the Hibernate Session generates an appropriate event and passes it to the configured event listener for that type. Out-of-the-box, these listeners implement the same processing in which those methods always resulted. However, you are free to implement a customization of one of the listener interfaces (i.e., the LoadEvent is processed by the registered implemenation of the LoadEventListener interface), in which case their implementation would be responsible for processing any load() requests made of the Session. The listeners should be considered effectively singletons; meaning, they are shared between requests, and thus should not save any state as instance variables. A custom listener should implement the appropriate interface for the event it wants to process and/or extend one of the convenience base classes (or even the default event listeners used by Hibernate out-of-the-box as these are declared non-final for this purpose). Custom listeners can either be registered programmatically through the Configuration object, or specified in the Hibernate configuration XML (declarative configuration through the properties file is not supported). Here's an example of a custom load event listener: You also need a configuration entry telling Hibernate to use the listener in addition to the default listener: ... ]]> Instead, you may register it programmatically: Listeners registered declaratively cannot share instances. If the same class name is used in multiple <listener/> elements, each reference will result in a separate instance of that class. If you need the capability to share listener instances between listener types you must use the programmatic registration approach. Why implement an interface and define the specific type during configuration? Well, a listener implementation could implement multiple event listener interfaces. Having the type additionally defined during registration makes it easier to turn custom listeners on or off during configuration. Usually, declarative security in Hibernate applications is managed in a session facade layer. Now, Hibernate3 allows certain actions to be permissioned via JACC, and authorized via JAAS. This is optional functionality built on top of the event architecture. First, you must configure the appropriate event listeners, to enable the use of JAAS authorization. ]]> Note that <listener type="..." class="..."/> is just a shorthand for <event type="..."><listener class="..."/></event> when there is exactly one listener for a particular event type. Next, still in hibernate.cfg.xml, bind the permissions to roles: ]]> The role names are the roles understood by your JACC provider.