Forgot to say : using drools 5.6.FINAL

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De: "Vincent LEGENDRE" <vincent.legendre@eurodecision.com>
À: "Rules Users List" <rules-users@lists.jboss.org>
Envoyé: Jeudi 28 Août 2014 15:28:49
Objet: [rules-users] Inconsistent behaviour of insertLogical in rules having from pattern

Hi all,

It is 2 days I am fighting with a strange behaviour of insertLogical in rules having from pattern in conditions : it works the first time, and not after ...

-----------------------------------------

Here is my use-case (simplified) :

I have a class that represent a Flight. A Flight has a start/end datetime and is associated with a Airplane and a list of Crew :

class Flight {

    String airplaneId;

    List<String> crewIds;

    Date start;

    Date end;

}

I want to maintain an alert list that contains all overlaps for each airplane and each crew. So I have rules like:

rule "Overlap Airplane"

   when

      $f1 : Flight($airplaneId : airplaneId)

      $f2 : Flight(this != $1, airplaneId == $airplaneId, ... and periods intersecting ... )

   then

      insertLogical(new Alert(...));

end

rule "Overlap Crews"

   when

      $f1 : Flight()

      $crew : String from $f1.getCrewIds()

      $f2 : Flight(this != $1, eval($f2.getCrewIds().contains($crew)) , ... and periods intersecting ... )

   then

      insertLogical(new Alert(...));

end

-----------------------------------------

Ok. So what I do to test all that stuff :

  - create a new session

  - add a first single Flight --> no alerts at all, normal

  - add a second Flight insersecting the first one with same airplane and same crews list --> 3 new alerts inserted (one for airplane, one for each crew) : normal

  - remove this second Flight --> the 3 preivous alerts are retracted : still ok

  - re-add this second Flight --> only the 'airplane' rule triggers, I only get one new alert insteads of the previous same 3 .... The alerts not inserted correspond to the rule having 'from' in it

-----------------------------------------

To test that it is the source of the problem, I add a new explicit association object that I insert in WM :

class CrewAffectation {

    String idCrew;

    String idFlight;

}

For each inserted Flight, I also insert corresponding new CrewAffectation objects. (in case of retract, I retract them of course).

I change the last rule to something like :

rule "Overlap Crews"

   when

      $f1 : Flight($id1 : id

      $f2 : Flight(this != $1, $id2 : id, ... and periods intersecting ... )

        $crewAff1 : CrewAffectation($idCrew : idCrew, idFlight== $id1)
        $crewAff2 : CrewAffectation(idCrew == $idCrew, idFlight== $id2)  

    then

      insertLogical(new Alert(...));

end

And with this 'no-from' approach, everything is working as expected.

-----------------------------------------

In addition, I suspect the truth maintenance system to have leaks, and notably in the source kBase.

Why ? Because I was facing problems by reusing the same kBase to generate multiples kSessions : The first session created reacted well, while all the folowing not.

And it was in fact the same problem as the one described here : usage of from and insertLogical in the same rule.

The first created session adds and retract my 3 alerts, the second created session only adds the airplane alert.

With using the explicit association object, I can reuse my kBase and everything is working well.

-----------------------------------------

Does someone already faced the problem ?

Does it looks like a real bug to dev team or am I doing something wrong (but as it work once, I guess it is a bug) ?

Vincent

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