Re: [rules-users] Drools + EMF + CDO

Several remarks: (1) Make sure that a parent is asserted after all of its children. Otherwise initial evaluation will not comprise the entire children's list.

(2) After changing a child's state, update the parent. (3) The rule as you have it now is somewhat circumstantial. A simpler approach would be rule NoUpChild when $p : Device( $children : eContents, eContents.size > 0 ) not( Device( state == "UP" ) from $children ) then System.out.println( $p.getId() + ": no child up" ); end (4) If you have a "parent" field, this could even be written: rule NoUpChild when $p : Device( children.size > 0 ) not( Device( parent == $p, state == "UP" ) ) then System.out.println( $p.getId() + ": no child up" ); end

-W 2010/8/2 Georg Maier <Georg.Maier(a)cjt.de&gt; > Hi, > > > > I’m trying to figure out an issue for three days now and I’m getting kind > of desperate, so I hope someone can help. > > I’m using Drools in combination with an EMF model which is modeling a > computer network. On init, I read the whole structure of the model and > insert all elements into the working memory. Some of the entities share the > super class “Device” which has an attribute “state”. > > > > Now I’m having the following rule to change an attribute of one of the > model entities: > > > > *rule* "Set received status to model" > > *when* > > $event : SomeEvent ( > > $hostname : hostname, > > $hoststate : hoststate, > > $timestamp : timestamp > > ) > > > > $device : Device ( > > name == $hostname > > ) > > > > *then* > > *modify*($device) { > > setState($hoststate); > > } > > db.commit(*false*); > > > > *retract*($event); > > System.err.println("Set status of " + $device + " to " + > $hoststate); > > *end* > > > > … which works perfectly fine. Anyway, what I want to do in this test case > is to *react whenever all child devices of a mutual parent device* (e.g. > hosts on one switch) are no longer reachable. I thought of a rule like the > following: > > > > *rule* "Parent Children Test" > > *when* > > $parent : Device ( > > $children : eContents, > > eContents.size > 0 > > ) > > > > *forall* ( > > $child : Device ( > > state == "DOWN" > > ) *from* $children > > ) > > > > *then* > > … > > *end* > > * * > > … which by the way worked perfectly fine as long as I was not using > objects from a model. My first idea was that for some strange reason the > object might get copied so that I actually would have two different > references after modifying it, but this is not the case. When I initialize > the rule base with the circumstances that the second rule would fire, it > really does. It just seems as it would not being evaluated after changing > the attribute, but this is not the case either! So all I can think of is > some strange caching, maybe in combination with the *forall *statement? > Maybe someone has some experience when using Drools with EMF + CDO and > experienced as similar issue? > > Any help would be very very very much appreciated! > > Thanks in advance > > > > Georg > > _______________________________________________ > rules-users mailing list > rules-users(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/rules-users > >