6:22 a.m.
Hello group,
Assuming I have the rule:
rule "try not to loop"
when
$a : A($code : code)
$b : B(parentCode == $code)
then
addResult($a, $b);
end
and the classes:
public class A {
int code;
}
public class B {
int parentCode;
}
I insert into the WM 4 objects :
A(code = 1), A(code = 2);
B(parentCode=1), B(parentCode = 2);
I would like that after calling fireAllRules() only 1 match will be
returned. I have no preference regarding which one, in the current situation
2 matches are returned.
Anyone could suggest a method to enforce this ?
Thank you,
Maxim.
8:15 a.m.
New subject: Not looping the rule when more then 1 valid match is found
It depends on what addResult() does and if you need the actual values of
A() and B(). Forward chaining engines are "data driven" and as so, changes
to your data (facts) are what cause the engine to cancel activations.
So, if you don't need the actual values of A and B, use "exists":
exists( A( $c : code) and B(parentCode == $c) )
Although, since addResult() uses them as parameters, I guess it is not
the case. So, does addResult() changes your facts in any way? Lets say
addResult() creates a Association fact between A and B, you could write:
when
$a : A( $c : code )
$b : B( parentCode == $c )
not( Association( <you can constraint something here if you want> ) )
then
Or if A and B have an attribute that is set by addResult()
when
$a : A( $c : code )
$b : B( parentCode == $c )
not( A( resultAdded == true ) and B( resultAdded == true ) )
then
So, in the end, rules in forward chaining are about taking actions
triggered by a given data state. Write rules that react to the expected
state and change the state accordingly.
Oh, obviously you can always use fire limit or halt to "pause" the
execution if that is what you want too.
session.fireAllRules( 1 ); // fires only one rule and returns control to the
application
Or:
when
$a : A( $c : code )
$b : B( parentCode == $c )
then
addResult( $a, $b );
drools.halt();
end
After firing the above rule, stop firing rules and return the control to
the application. Above situations will only pause the engine. All
activations that were not fired will remain in the agenda waiting for the
next call to fireAllRules() to be fired.
[]s
Edson
2009/1/26 Maxim Veksler <maxim.veksler(a)gmail.com>
Hello group,
Assuming I have the rule:
rule "try not to loop"
when
$a : A($code : code)
$b : B(parentCode == $code)
then
addResult($a, $b);
end
and the classes:
public class A {
int code;
}
public class B {
int parentCode;
}
I insert into the WM 4 objects :
A(code = 1), A(code = 2);
B(parentCode=1), B(parentCode = 2);
I would like that after calling fireAllRules() only 1 match will be
returned. I have no preference regarding which one, in the current situation
2 matches are returned.
Anyone could suggest a method to enforce this ?
Thank you,
Maxim.
_______________________________________________
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rules-users(a)lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users
--
Edson Tirelli
JBoss Drools Core Development
JBoss, a division of Red Hat @ www.jboss.com
9:27 a.m.
New subject: Not looping the rule when more then 1 valid match is found
I wonder if you can use a Global (or a static variable) to do the same without really
changing your rule.
Something like this.
Global Integer ruleFired;
rule "try not to loop"
when
$a : A($code : code)
$b : B(parentCode == $code)
then
if(ruleFired != 1)
{
addResult($a, $b);
Drools.getWorkingMemory().setGlobal(“ruleFired”,1);
}
end
From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On
Behalf Of Maxim Veksler
Sent: Monday, January 26, 2009 5:52 PM
To: Rules Users List
Subject: [rules-users] Not looping the rule when more then 1 valid match is found
Hello group,
Assuming I have the rule:
rule "try not to loop"
when
$a : A($code : code)
$b : B(parentCode == $code)
then
addResult($a, $b);
end
and the classes:
public class A {
int code;
}
public class B {
int parentCode;
}
I insert into the WM 4 objects :
A(code = 1), A(code = 2);
B(parentCode=1), B(parentCode = 2);
I would like that after calling fireAllRules() only 1 match will be returned. I have no
preference regarding which one, in the current situation 2 matches are returned.
Anyone could suggest a method to enforce this ?
Thank you,
Maxim.
MASTEK LTD.
Mastek is in NASSCOM's 'India Top 20' Software Service Exporters List.
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2 comments
3 participants
participants (3)
-
Edson Tirelli -
Maxim Veksler -
Vikrant Yagnick