[rules-users] Drools + EMF + CDO

[Georg Maier]

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

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