[rules-users] "Exists" CE behaviour

[Viswanathan Nageswaran]

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                                             
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                                       [rules-users] "Exists" CE behaviour 
                                                                           
             13/07/2009 14:11                                              
                                                                           
                                                                           
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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++) {     session.insert(new Foo());
}

// 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"     when                exists (Foo());         //not ( not
( Foo() ) ); (2)     then              System.out.println("Rule fired...");
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.
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