[rules-users] WorkingMemoryEventListener and Stateless sessions in sequential mode

[Bruno Freudensprung]

Hi,

I am using Drools 5.1.1 and I have the impression that the 
WorkingMemoryEventListener is not called when using a 
StatelessKnowledgeSession configured in Sequential mode.
Does anyone have experienced such a behavior?

When using the SequentialOption.NO option, the little program below (in 
PS) displays:

Retracting: to-be-removed
Retracted: to-be-removed

When using the SequentialOption.YES option, the program displays:

Retracting: to-be-removed

Many thanks in advance,

Bruno.

PS : Here is the sample code

// DRL:
rule "Retract to-be-removed string"
    when
        $s : String(this == "to-be-removed")
    then
        System.out.println("Retracting: " + $s);
        retract($s);
end

// listener:
    public class MyListener implements 
org.drools.event.rule.WorkingMemoryEventListener {
        public void objectInserted(
                org.drools.event.rule.ObjectInsertedEvent event) {
        }
        public void 
objectRetracted(org.drools.event.rule.ObjectRetractedEvent event) {
            System.out.println("Retracted: " + 
event.getOldObject().toString());
        }
        public void 
objectUpdated(org.drools.event.rule.ObjectUpdatedEvent event) {
        }
    }

// main:
        KnowledgeBuilder builder = 
KnowledgeBuilderFactory.newKnowledgeBuilder();
        builder.add(ResourceFactory.newFileResource(new 
File("simpleRule.drl")),ResourceType.DRL);
        KnowledgeBaseConfiguration configuration = 
KnowledgeBaseFactory.newKnowledgeBaseConfiguration();
        configuration.setOption(SequentialOption.YES); // change this 
line to change the program behavior
        KnowledgeBase knowledgeBase = 
KnowledgeBaseFactory.newKnowledgeBase(configuration);
        knowledgeBase.addKnowledgePackages(builder.getKnowledgePackages());
        StatelessKnowledgeSession session = 
knowledgeBase.newStatelessKnowledgeSession();
        MyListener handler = new MyListener();
        List<Command<?>> commands = new ArrayList<Command<?>>();
        commands.add(CommandFactory.newInsert("to-be-removed"));
        commands.add(new AddEventListenerCommand(handler));
        session.execute(CommandFactory.newBatchExecution(commands));