13.7 Understanding Event Listeners

The Event Listener mechanism detects specific business events and stores the event details for certification. The stored event details are called Certification Event Triggers, and these are processed into certifications by the Certification Event Trigger Task, running as a scheduled job. The business events currently detected by event listeners are modifications of Oracle Identity Manager users, either individually or in bulk.

Every event listener contains a ruleset and a certification definition, as described in "Managing Certification Definitions". The ruleset contains one or more rules, each of which tests one or more conditions and specifies an action to take if its conditions are met. The standard action for event listener rules is to store a Certification Event Trigger that identifies the event listener, the user or users that were modified, and the certification definition that should be generated in response to this event.

Triggers accumulate between runs of the Certification Event Trigger Job. When the job runs, it groups the triggers by their event listener identifiers, and then processes each group according to the corresponding event listener's properties. By default, the trigger job creates a certification for all users in each group of triggers, using the listener's certification definition as the template for the certification. After this, the triggers from the completed group are deleted.

There are several properties that affect how an event listener's triggers will be processed by the trigger job. The first property determines whether the listener is in active or disabled state. If a listener is disabled, then its rules are no longer evaluated when business events occur, and therefore, no triggers are stored from that listener. If a listener stored triggers before being disabled, then the next trigger job run deletes those triggers without processing them. When a disabled listener is set back to active state, it can once again store triggers that are processed by the trigger job.

Another event listener property that affects trigger processing is its Event Count, which limits how many triggers may be processed for the listener during a single run of the trigger job. This setting is optional. If it is not specified, then the number is unlimited. If the event count is specified, then it represents the maximum number of triggers that may be processed. When the trigger job runs, it checks the listener's event count for each batch of triggers, and if the number of triggers exceeds the event count, then the triggers are discarded without generating a certification. This feature is useful for preventing huge certifications from being created when users are modified in bulk.

Finally, the trigger job itself may be configured to process the triggers from certain event listeners, but not others. This feature is controlled by a Certification Event Trigger Task parameter titled Event Listener Name List. If this parameter is left blank in the definition of the trigger job, then triggers from all listeners are processed when the trigger job runs. If the name list is defined, then only the listeners in that list have their triggers processed when the job runs; triggers from other listeners are ignored and retained for future trigger job runs. When multiple instances of scheduled jobs are defined for the Certification Event Trigger Task, then each list of event listeners can have its triggers processed on the most appropriate schedule.