// Attach an observer to the engine 

IlrToolAdapter engineObserver = new IlrToolAdapter() {

   // override some of the notification methods

   public void notifyAssertObject(Object object) {

      //invoked when an object is added

      System.out.println(object + " is added");

   }

   public void notifyRetractObject(Object object) {

      //invoked when an object is retracted

      System.out.println(object + " is retracted");

   }

   public void notifyBeginInstance(IlrRuleInstance instance) {

      // invoked when the engine executes a rule instance

      // with the RetePlus algorithm

      System.out.println(instance.getRuleName());

   }

   public void notifyBeginSequentialInstance(		

               IlrRule rule,Object[] objs,int arg) {

      // invoked when the engine executes 

      // a rule in sequential mode

      System.out.println(rule.getName());

   }

};

try {

   engine.connectTool(engineObserver);

} catch (IlrToolConnectionException e) {

   e.printStackTrace();

}