[rules-users] Drools fusion forward chaining

Ahmed Hafsi hafsi at fzi.de
Mon Aug 24 09:09:00 EDT 2009


Hi guys , 

I am using the lastest version of DROOLS , i.e 5.0 , I am trying to achieve
forward chaining with the new features of Fusion
I was looking for examples about the different operators and how to make use
of them but the broker example does not mention in it's DRL file any time
related operators , i.e after , meets ...
I would be grateful if you guys provide me with a simple example of forward
chaining (sequence)
My goal to achieve is to implement something like this :
CmplxEvent :- a and then b and then c

my drools rule is :

rule "cmplx0"
when
 $a : Event()
 $b : Event()
 Event(this after $b && $b after $a)
then
 //whatever
end

however this does not work , it complains about "unable to create field
exatractor"
Event is an event that I have declared using declare Event and then the
metadata @event as described in the docs.


Thanks for help.
Khalil Hafsi




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