[jboss-jira] [JBoss JIRA] Commented: (JBRULES-2278) NPE after knowledgebase updated when using entrypoints

[Edson Tirelli (JIRA)]

    [ https://jira.jboss.org/jira/browse/JBRULES-2278?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12498040#action_12498040 ] 

Edson Tirelli commented on JBRULES-2278:
----------------------------------------

Nestor,

You are using the java dialect, so using the above snippet you will get the following errors:

Rule Compilation error total cannot be resolved
total cannot be resolved
total cannot be resolved
total cannot be resolved
Syntax error on token ";", delete this token

That is because in java all variables must be explicitly typed ("int total") and the result block must not have a ";". If you change your rule to the following:

		$t2: Number(intValue > 3) from accumulate(TestModel( test == "2", id != $t1.id, this after [0s,1m] $t1) 
		                                          from entry-point "MyEntryPoint",
		                                          init( int total = 0; ),
		                                          action( total++; ),
		                                          reverse( total--; ),
		                                          result( total )) 

It works just fine. Another alternative is to use "mvel" dialect in which case you don't need to explicitly type the variables, nor use ";" on each expression:

rule "Your Second Rule"
	no-loop true
	dialect "mvel"
	when
		$t1: TestModel( test == "2" ) from entry-point "MyEntryPoint"
		$t2: Number(intValue > 3) from accumulate(TestModel( test == "2", id != $t1.id, this after [0s,1m] $t1) 
		                                          from entry-point "MyEntryPoint",
		                                          init( total = 0 ),
		                                          action( total++ ),
		                                          reverse( total-- ),
		                                          result( total )) 


That also works fine for me.

As I mentioned before, I am testing against trunk, using the attached example. I believe you might be seeing the exceptions, but I need to reproduce in order to understand what is happening.

Thanks,
Edson

> NPE after knowledgebase updated when using entrypoints
> ------------------------------------------------------
>
>                 Key: JBRULES-2278
>                 URL: https://jira.jboss.org/jira/browse/JBRULES-2278
>             Project: Drools
>          Issue Type: Bug
>      Security Level: Public(Everyone can see) 
>          Components: drools-core, drools-core  (expert), drools-core (fusion)
>    Affects Versions: 5.0.1.FINAL
>            Reporter: Michael Neale
>            Assignee: Edson Tirelli
>             Fix For: 5.1.0.M2
>
>         Attachments: kagent-problem.zip
>
>
> Raised by Nestor Burriel on the dev list: 
> I've tried to configure my rule engine obtaining unexpected behaviour.
> I configure my statefulSession as follows:
> wm = (ReteooStatefulSession) ((KnowledgeBaseImpl) kagent
> .getKnowledgeBase()).ruleBase.newStatefulSession(
>                                (SessionConfiguration) sessionConf, env);
> ksession = new StatefulKnowledgeSessionImpl(wm, kagent.getKnowledgeBase());
> And after updating the KnowledgeBase in the agent I update my ksession:
> wm.setRuleBase((InternalRuleBase) ((KnowledgeBaseImpl) kagent
> .getKnowledgeBase()).ruleBase);
> ksession = new StatefulKnowledgeSessionImpl(wm, kagent.getKnowledgeBase());
> Without using entry-points this approach works as expected, but using them
> it fails after the first update throwing the error:
> Exception while processing message: java.lang.NullPointerException
> java.lang.NullPointerException
>        at
> org.drools.reteoo.ReteooFactHandleFactory.newFactHandle(ReteooFactHandleFactory.java:54)
>        at
> org.drools.common.AbstractFactHandleFactory.newFactHandle(AbstractFactHandleFactory.java:79)
>        at
> org.drools.common.AbstractFactHandleFactory.newFactHandle(AbstractFactHandleFactory.java:66)
>        at
> org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:109)
>        at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:80)
>        at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:28)
> Browsing the drools core code I found the line that was throwing the
> exception and tried to get the same result by implementing:
> if (!((InternalRuleBase) ((KnowledgeBaseImpl)
> ksession.getKnowledgeBase()).ruleBase)
>                                .getTypeDeclaration(fact.getClass()) ==
> null)
>        log.info (((InternalRuleBase) ((KnowledgeBaseImpl)
> ksession.getKnowledgeBase()).ruleBase)
> .getTypeDeclaration(fact.getClass()).getTimestampExtractor().toString());
> after updating my ksession. The result was the same, again the same
> exception thrown but my logger wrote:
> 18:01:50,232 INFO [ClassFieldExtractor class=MyPackage.MyFact
> field=myTimestampField]
> So I dont know why the core is throwing that exception, is that
> implementation correct?, any ideas?
> Thanks,
> Nestor

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