Simple Example

Drools provides the DefaultWorkingMemoryEventListener which is an empty method implementation of WorkingMemoryEventListener.:

To execute code when an event is generated we override any of the above methods. All event objects return references back to the working memory. The following example shows how we can listen to when an object is asserted into the WorkingMemory.

Debug Example

Events can be used for debugging, to help with this drools provides the DebugWorkingMemoryEventListener class:

Each event object already has a toString() method to print information about itself, to use the class :

The HelloWorld example shows the Event Model being used to provide debug information.