[rules-users] Inserting a fact via a specific entry point inside a rule

[Justin King]

Hi Everyone,

I'm aware that in Drools you can use 'insert()' in the 'then' part of a rule
to insert a new fact into the memory, meaning more rules may be fired based
on the addition of this new fact. I wish to do a similar thing, but I wish
to insert the fact into a specific entry point. My current rule code to do
this is:

rule "Allow message buyBook"
no-loop true
    when
        $event : MessageRecievedEvent(operationName == "buyBook") from
entry-point "t1 stream"
    then
        MessageRecievedEvent mre = new MessageRecievedEvent();
        mre.setOperationName("sellBook");
        StatefulKnowledgeSession session =
kcontext.getKnowledgeRuntime().getKnowledgeBase().newStatefulKnowledgeSession();
        WorkingMemoryEntryPoint obStream =
session.getWorkingMemoryEntryPoint("ob1 stream");
        obStream.insert(mre);
        session.fireAllRules();
end

rule "ob1"
no-loop true
    when
        $event : MessageRecievedEvent(operationName == "sellBook") from
entry-point "ob1 stream"
    then
        System.out.println("executed");
end

Which is pretty hideous, but it does work, causing the second rule to fire
after the first one. What I would like is something like:

rule "Allow message buyBook"
no-loop true
    when
        $event : MessageRecievedEvent(operationName == "buyBook") from
entry-point "t1 stream"
    then
        MessageRecievedEvent mre = new MessageRecievedEvent();
        mre.setOperationName("sellBook");
        insert(mre, "ob1 stream")
end

rule "ob1"
no-loop true
    when
        $event : MessageRecievedEvent(operationName == "sellBook") from
entry-point "ob1 stream"
    then
        System.out.println("executed");
end

Is something like this possible or will I have to write a function to do it?
I'm also a bit concerned about the performance hit of creating a whole new
StatefulKnowledgeSession to fire the second rule, I'd like to just use the
current one.

Thanks,

Justin

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