[rules-users] need design suggestion
Wolfgang Laun
wolfgang.laun at gmail.com
Wed Apr 4 07:01:49 EDT 2012
Try the more direct approach:
$port: Port ( state == State.DOWN )
$pe : PathElement(state == State.UP, ports contains $port )
(However, I don't see the flaw in your rule code right away.)
But DO NOT call halt() from a thread that inserts and does not sync
with the thread running the Enging (fireUntilHalt()). This might kill
the bee before you can harvest the honey!
Simply call fireAllRules after you've inserted your facts (all in 1
thread), or let the thing run for a while (sleep).
-W
On 03/04/2012, Joe Zendle <jzendle at gmail.com> wrote:
> Wolfgang, thanks much. Helps me understand what's going on under the hood a
> little better.
>
> I'm having a similar issue with the next higher container. I have say,
> PathElements which contain a collection of Ports. Same problem as before -
> if one Port goes down then the PathElement goes down. I can't seem to
> express it properly in DRL
>
> The only thing that comes to me is:
>
> rule "pe down"
> when
> // pe is active
> $pe : PathElement(state == State.UP )
> // and any one of the ports are down
> Port ( state == State.DOWN ) from $pe.ports
> then
> System.out.println(" setting pe down" + $pe );
> modify($pe) {
> setState( State.DOWN);
> }
> end
>
> However, like my other naive attempts, it is not firing after the
> Notification is inserted into WM. I tried many variations using a 'collect'
> clause, etc to no avail. Any additional insight would be greatly
> appreciated.
>
> BTW, once i get a handle on the one-to-many associations I promise I'll
> stop :-)
>
>
> On Mon, Apr 2, 2012 at 11:47 PM, Wolfgang Laun
> <wolfgang.laun at gmail.com>wrote:
>
>> See inline.
>>
>> On 02/04/2012, Joe Zendle <jzendle at zentechinc.net> wrote:
>> >
>> >
>> > Here are my rules:
>> >
>> > rule "card going down"
>> > when
>> // There is a Card in state UP and...
>> > $card : Card($name : name , state == State.UP)
>> // a matching notification to DOWN
>> > $notif : Notification( id == $name, type ==
>> NotificationType.CARD ,
>> > state == State.DOWN )
>> > then
>> > System.out.println(" got notification for card down " + $card );
>> > modify($card) {
>> > setState(State.DOWN);
>> > }
>> > retract($notif);
>> > end
>> >
>> > // is the following rule correct??
>>
>> No.
>>
>> >
>> > rule "port going down"
>> > when
>>
>> // There is a Port in State UP and...
>>
>> > $port : Port($name : name , state == State.UP, $card : card)
>> // ...take its Card and if this is DOWN
>>
>> > Card ( state == State.DOWN) from $card
>> > then
>> > System.out.println(" port down because card is down port: " +
>> $port +
>> > " card: " + $card );
>> > modify($port) {
>> > setState(State.DOWN);
>> > }
>>
>> The difference between these two rules is that the first one is triggered
>> by
>> a change in WM - the emergence of a matching Notification. The second,
>> however, is evaluated when the Port enters WM, presumably with its
>> Card in working order. Subsequently, Port doesn't change and so evaluation
>> is never retried.
>>
>>
>> Two correct versions:
>>
>> when
>> $card : Card( state == State.DOWN )
>> $port : Port($name : name , state == State.UP, card == $card)
>> then
>>
>> when
>> $port : Port($name : name , state == State.UP, $card: card )
>> Card( this == $card, state == State.DOWN )
>> then
>>
>> Or, assuming that Port must follow Card, for going UP and DOWN:
>>
>> when
>> $card : Card( $stateCard: state )
>> $port : Port($name : name , state != $stateCard, card == $card)
>> then
>> modify($port) {
>> setState($stateCard)
>> }
>>
>>
>> >
>> > end
>> >
>> > Here is the test case in a nutshell:
>> >
>> > Port port1 = new Port();
>> > Port port2 = new Port();
>> > port1.setName("port1");
>> > port2.setName("port2");
>> >
>> > Card card1 = new Card();
>> > card1.setName("port1 card1")
>> > port1.setCard(card1);
>> > // stateful session
>> > ksession.insert(port1);
>> > ksession.insert(port2);
>> > ksession.insert(card1);
>> >
>> > System.out.println(" firing rules");
>> > new Thread(new Runnable() {
>> > public void run() {
>> > ksession.fireUntilHalt();
>> > }
>> > }).start();
>> >
>> > System.out.println("*** injecting notification down");
>> > Notification notif = new Notification();
>> > notif.setType(NotificationType.CARD);
>> > notif.setState(State.DOWN);
>> > notif.setId("port1 card1");
>> > FactHandle notifHandle = ksession.insert(notif);
>> >
>> >
>> > ksession.halt();
>> > ksession.dispose()
>> >
>> >
>> > I would expect the card down notification to cause the port to do down
>> > by
>> > the second rule above but it does not fire.
>> >
>> > Here is output
>> >
>> > card1: Card [state=UP, name=port1 card1,
>> > ne=org.plugtree.examples.model.NE at 1e2670b]
>> > OBJECT ASSERTED value:Port [state=UP, name=port1, card=Card [state=UP,
>> > name=port1 card1, ne=org.plugtree.examples.model.NE at 1e2670b]] factId: 1
>> > OBJECT ASSERTED value:Port [state=UP, name=port2, card=Card [state=UP,
>> > name=port1 card1, ne=org.plugtree.examples.model.NE at 1e2670b]] factId: 3
>> > OBJECT ASSERTED value:Card [state=UP, name=port1 card1,
>> > ne=org.plugtree.examples.model.NE at 1e2670b] factId: 5
>> > firing rules
>> > 3
>> > *** injecting notification down
>> > ACTIVATION CREATED rule:card going down activationId:card going down [6,
>> 5]
>> > declarations: $name=port1 card1(5);
>> > $notif=org.plugtree.examples.model.Notification at 4a9a7d(6); $card=Card
>> > [state=UP, name=port1 card1, ne=org.plugtree.examples.model.NE at 1e2670b
>> ](5)
>> > OBJECT ASSERTED
>> value:org.plugtree.examples.model.Notification at 4a9a7dfactId:
>> > 6
>> > BEFORE ACTIVATION FIRED rule:card going down activationId:card going
>> > down
>> > [6, 5] declarations: $name=port1 card1(5);
>> > $notif=org.plugtree.examples.model.Notification at 4a9a7d(6); $card=Card
>> > [state=UP, name=port1 card1, ne=org.plugtree.examples.model.NE at 1e2670b
>> ](5)
>> > got notification for card down Card [state=UP, name=port1 card1,
>> > ne=org.plugtree.examples.model.NE at 1e2670b]
>> > OBJECT MODIFIED value:Card [state=DOWN, name=port1 card1,
>> > ne=org.plugtree.examples.model.NE at 1e2670b] factId: 5
>> > OBJECT RETRACTED
>> > value:org.plugtree.examples.model.Notification at 4a9a7dfactId: 6
>> > AFTER ACTIVATION FIRED rule:card going down activationId:card going down
>> > [-1, 5] declarations: $name=port1 card1(5); $card=Card [state=DOWN,
>> > name=port1 card1, ne=org.plugtree.examples.model.NE at 1e2670b](5)
>> >
>> >
>> >
>> > Is the second rule written incorrectly? or do i have a gap in my
>> > expectations of how the engine should work (or both)
>> >
>> > Thanks in advance,
>> >
>> > Joe.
>> >
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>
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