Re: [rules-users] need design suggestion
On 03/04/2012, Joe Zendle <jzendle(a)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.
Forget from when you have all relevant objects as facts in WM.
Rule "pe down" is evaluated while all the Ports are still OK, and so
nothing happens. When the Port is set DOWN, there's no reason for
Drools to re-evaluate this rule.
Reevaluation of patterns in front of "from" is not triggered by
updates of facts with the same type. Only an update of a PathElement
would do this.
-W