[rules-users] "Exists" CE behaviour

Wolfgang Laun wolfgang.laun at gmail.com
Mon Jul 13 09:16:40 EDT 2009 

I changed the rule names intentionally. It shouldn't matter, for the
test, whether both are present or the second load overrides the 1st
rule.
-W

On 7/13/09, Chivotario Martin <chivotario at gmail.com> wrote:
> Hi Wolfgang,
>
> Just seen the JIRA Issue it seems test1.drl got some copy-paste problems ,
> because both rules are present :D.
> However, thanks for creating the issue !
>
> Regards,
> Manuel.
>
>
>
> 2009/7/13 Wolfgang Laun <wolfgang.laun at gmail.com>
>
>> https://jira.jboss.org/jira/browse/JBRULES-2206 created.
>>
>> Thanks for the code!
>> -W
>>
>> On 7/13/09, Chivotario Martin <chivotario at gmail.com> wrote:
>> > Hi Wolfgang,
>> >
>> > I do not know if i can use the issue tracker to post this as an issue,
>> > as
>> i
>> > don't know if i'm allowed to do so, and also if this is officially,
>> really a
>> > bug or the expected behaviour :) .
>> >
>> > However i left a complete piece of code showing the behaviour i'm
>> > getting
>> :
>> >
>> > RuleTester.java
>> >
>> > package org.drools.test;
>> >
>> > import org.drools.KnowledgeBase;
>> > import org.drools.KnowledgeBaseConfiguration;
>> > import org.drools.KnowledgeBaseFactory;
>> > import org.drools.RuleBaseConfiguration;
>> > import org.drools.builder.KnowledgeBuilder;
>> > import org.drools.builder.KnowledgeBuilderFactory;
>> > import org.drools.builder.ResourceType;
>> > import org.drools.io.ResourceFactory;
>> > import org.drools.runtime.StatefulKnowledgeSession;
>> >
>> > public class RuleTester {
>> >
>> >     private static final int MAX_EVENTS = 5;
>> >
>> >     public class Foo { }
>> >
>> >     public void test() {
>> >
>> >         KnowledgeBaseConfiguration config =
>> > KnowledgeBaseFactory.newKnowledgeBaseConfiguration();
>> >
>> > ((RuleBaseConfiguration)config).setRuleBaseUpdateHandler(
>> > null );
>> >         KnowledgeBase kbase =
>> > KnowledgeBaseFactory.newKnowledgeBase(config);
>> >
>> >         StatefulKnowledgeSession session =
>> > kbase.newStatefulKnowledgeSession();
>> >
>> >         for (int i=0; i<MAX_EVENTS; i++) {
>> >             session.insert(new Foo());
>> >         }
>> >
>> >         for (int i=1; i<3; i++) {
>> >             KnowledgeBuilder kbuilder =
>> > KnowledgeBuilderFactory.newKnowledgeBuilder();
>> >             kbuilder.add(
>> > ResourceFactory.newClassPathResource( "test"+i+".drl" ),
>> > ResourceType.DRL);
>> >
>> >             if( kbuilder.hasErrors() ) {
>> >                 System.out.println( kbuilder.getErrors() );
>> >                 return;
>> >             }
>> >
>> >             kbase.addKnowledgePackages(
>> > kbuilder.getKnowledgePackages() );
>> >
>> >             int fireCount = session.fireAllRules();
>> >
>> >             System.out.println("Test"+i+".drl , number of
>> > rules fired = "+fireCount);
>> >
>> >         }
>> >
>> >         session.dispose();
>> >
>> >     }
>> >
>> >     public static void main(String[] args) {
>> >         RuleTester tester = new RuleTester();
>> >         tester.test();
>> >     }
>> >
>> > }
>> >
>> >
>> > test1.drl
>> >
>> > import org.drools.test.RuleTester.Foo;
>> >
>> > rule "notNotRule"
>> >     when
>> >         exists ( Foo() );
>> >     then
>> >         System.out.println("Rule fired...");
>> > end
>> >
>> > test2.drl
>> >
>> > import org.drools.test.RuleTester.Foo;
>> >
>> > rule "notNotRule"
>> >     when
>> >         not ( not ( Foo() ) );
>> >     then
>> >         System.out.println("Rule fired...");
>> > end
>> >
>> >
>> > Using Drools 5.0.1-Final , the expected output would be :
>> >
>> > > Test1.drl , number of rules fired = 0
>> > > Rule fired...
>> > > Test2.drl , number of rules fired = 1
>> >
>> > If someone allows me to open this a a JIRA i would try to understand how
>> to
>> > use it :D and would do so.
>> >
>> > Regards,
>> > Manuel.
>> >
>> >
>> > 2009/7/13 Wolfgang Laun <wolfgang.laun at gmail.com>
>> >
>> > > Quite right, since not(not(Foo())) is equivalent to exists(Foo()).
>> > >
>> > > Martin, would you please submit a JIRA?
>> > >
>> > > -W
>> > >
>> > >
>> > >
>> > >
>> > >
>> > > On 7/13/09, Chivotario Martin <chivotario at gmail.com> wrote:
>> > > > Hi Visu,
>> > > >
>> > > > My understanding (also tested) is that activations are created no
>> matter
>> > the
>> > > > knowledge base has the rule packages loaded
>> > > > before or after the working memory is filled with facts, but the
>> > execution
>> > > > of the rules happens automatically if the working memory is filled
>> > > > in
>> > > > advance.Setting the RuleBaseUpdateHandler to null, prevents the
>> > execution of
>> > > > the rules but keeps activations to be created when adding a rule to
>> the
>> > > > kbase.
>> > > > In this case, it seems the exists CE only creates activations if the
>> > rules
>> > > > are loaded before the working memory is populated.
>> > > > But this doesn't happen if i change the statement :
>> > > >
>> > > >   exists ( Foo() ) --> not ( not ( Foo() ) )
>> > > >
>> > > > In this case, activations are created no matter whether the kbase is
>> > empty
>> > > > or not before populating the WM.
>> > > >
>> > > >
>> > > >
>> > > >
>> > > > 2009/7/13 Viswanathan Nageswaran <visu.nageswaran at in.ibm.com>
>> > > >
>> > > > > Chivotario,
>> > > > >
>> > > > > >From what I understand, the activation of rules happen as facts
>> are
>> > > > > inserted into the working memory; hence it is important for the
>> > session to
>> > > > > be begun against a knowledge base that has the rule packages
>> > > > > loaded
>> > before
>> > > > > the facts are inserted.
>> > > > >
>> > > > > -Visu
>> > > > >
>> > > > >
>> > > > >
>> > > > >
>> > > > >             Chivotario Martin
>> > > > >             <chivotario at gmail
>> > > > >             .com>
>> > To
>> > > > >             Sent by:                  rules-users at lists.jboss.org
>> > > > >             rules-users-bounc
>> > cc
>> > > > >             es at lists.jboss.or
>> > > > >             g
>> > Subject
>> > > > >                                       [rules-users] "Exists" CE
>> > behaviour
>> > > > >
>> > > > >             13/07/2009 14:11
>> > > > >
>> > > > >
>> > > > >             Please respond to
>> > > > >             Rules Users List
>> > > > >             <rules-users at list
>> > > > >               s.jboss.org>
>> > > > >
>> > > > >
>> > > > >
>> > > > >
>> > > > >
>> > > > >
>> > > > >
>> > > > > Hi ,
>> > > > >
>> > > > > I'm trying to use the Exists keyword within my rules with the
>> > following
>> > > > > snippet :
>> > > > >
>> > > > > // Create a session
>> > > > > KnowledgeBaseConfiguration config =
>> > > > >
>> > > >
>> > KnowledgeBaseFactory.newKnowledgeBaseConfiguration();
>> > > > >
>> > > >
>> > ((RuleBaseConfiguration)config).setRuleBaseUpdateHandler(
>> > > > null ); *
>> > > > > KnowledgeBase kbase =
>> > > > KnowledgeBaseFactory.newKnowledgeBase(config);
>> > > > > StatefulKnowledgeSession session =
>> > > > kbase.newStatefulKnowledgeSession();
>> > > > >
>> > > > > // Add some objects
>> > > > > for (int i=0; i<5; i++) {
>> > > > > }
>> > > > >
>> > > > >
>> > > > > // Add a DRL to the kbase
>> > > > > KnowledgeBuilder kbuilder =
>> > > > KnowledgeBuilderFactory.newKnowledgeBuilder();
>> > > > > kbuilder.add( ResourceFactory.newClassPathResource(
>> > > > "test/existsTest.drl"
>> > > > > ), ResourceType.DRL);
>> > > > > kbase.addKnowledgePackages(
>> > > > kbuilder.getKnowledgePackages() );
>> > > > >
>> > > > > // Fire rules
>> > > > > int fireCount = session.fireAllRules();
>> > > > >
>> > > > >
>> > > > > existsTest.drl :
>> > > > >
>> > > > > rule "existsTest"
>> > > > > ( Foo() ) ); (2)
>> > > > >
>> > > > > end
>> > > > >
>> > > > > When launched , the rule is not fired (no messages , fireCount 0),
>> but
>> > it
>> > > > > is when changing
>> > > > > exists with a double not condition (2).
>> > > > > If the working memory is populated after adding the rules file,
>> > > > > the
>> > exists
>> > > > > CE works as expected.
>> > > > > * I've used no RuleBaseUpdateHandler preventing automatic
>> activations
>> > to
>> > > > be
>> > > > > executed so fireAllRules can be used to get the fireCount, but
>> > commenting
>> > > > > this line out doesn't change the results.
>> > > > >
>> > > > > Probably i'm doing something wrong so a little help would be very
>> > > > > appreciated.
>> > > > >
>> > > > > Regards,
>> > > > > Manuel.
>> > > > > _______________________________________________
>> > > > > rules-users mailing list
>> > > > > rules-users at lists.jboss.org
>> > > > > https://lists.jboss.org/mailman/listinfo/rules-users
>> > > > >
>> > > > >
>> > > > >
>> > > > > _______________________________________________
>> > > > > rules-users mailing list
>> > > > > rules-users at lists.jboss.org
>> > > > > https://lists.jboss.org/mailman/listinfo/rules-users
>> > > > >
>> > > >
>> > > >
>> > > > _______________________________________________
>> > > > rules-users mailing list
>> > > > rules-users at lists.jboss.org
>> > > > https://lists.jboss.org/mailman/listinfo/rules-users
>> > > >
>> > > >
>> > > _______________________________________________
>> > > rules-users mailing list
>> > > rules-users at lists.jboss.org
>> > > https://lists.jboss.org/mailman/listinfo/rules-users
>> > >
>> >
>> >
>> > _______________________________________________
>> > rules-users mailing list
>> > rules-users at lists.jboss.org
>> > https://lists.jboss.org/mailman/listinfo/rules-users
>> >
>> >
>> _______________________________________________
>> rules-users mailing list
>> rules-users at lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/rules-users
>>
>

More information about the rules-users mailing list