[rules-users] New in Drools, java.lang.NullPointerException at org.drools.reteoo.AccumulateNode.getFirstMatch(AccumulateNode.java:967)

[Manuel Ortiz]

Hello, Mauricio:

I've been trying to reduce the set of rules and facts as well as the
condition elements to provide you a manageable example and this is the
minimal set of rules that still shows the NullPointerException behaviour. I
also attach a basic DroolsTest.java class which can be executed with these
rules. I'm using Drools 5.1.1.

The strange interaction is as follows:

   - As Rule 5 is not fired, everything is OK.
   - After Rule 5 firing, the next Rule 4 firing which leads to a new Rule 5
   activation fails with NullPointerException in AccumulateNode.
   - If Rule 6 is not included in the rule set, Rule 5 is activated and
   fired OK for every occassion.

Thank you very much for your time.

Best Regards,

Manuel Ortiz.

2011/3/31 Mauricio Salatino <salaboy at gmail.com>

> can you share your rules, so we can take a look at what is happening?
> The stack trace doesn't offer too much information to be able to analyze
> what happen.
>
>
> 2011/3/30 Manuel Ortiz <manuel.ortizramos at gmail.com>
>
>> Hello all!
>>
>> I am new in Drools but day by day, test by test, I think I get a bit more
>> knowledge of how the rule engine works from user point of view. I've been
>> adding rules to an alarm system, increasing the complexity and functionality
>> in several steps. Unfortunately in the last step I found the following
>> NullPointerException inside the rule engine...
>>
>> java.lang.NullPointerException
>> at org.drools.reteoo.AccumulateNode.getFirstMatch(AccumulateNode.java:967)
>> at
>> org.drools.reteoo.AccumulateNode.modifyLeftTuple(AccumulateNode.java:329)
>>  at
>> org.drools.reteoo.SingleLeftTupleSinkAdapter.propagateModifyChildLeftTuple(SingleLeftTupleSinkAdapter.java:239)
>> at
>> org.drools.reteoo.AccumulateNode.evaluateResultConstraints(AccumulateNode.java:640)
>>  at
>> org.drools.reteoo.AccumulateNode.assertObject(AccumulateNode.java:270)
>> at org.drools.reteoo.BetaNode.modifyObject(BetaNode.java:312)
>>  at
>> org.drools.reteoo.CompositeObjectSinkAdapter.doPropagateModifyObject(CompositeObjectSinkAdapter.java:460)
>> at
>> org.drools.reteoo.CompositeObjectSinkAdapter.propagateModifyObject(CompositeObjectSinkAdapter.java:428)
>>  at org.drools.reteoo.AlphaNode.modifyObject(AlphaNode.java:160)
>> at
>> org.drools.reteoo.CompositeObjectSinkAdapter.doPropagateModifyObject(CompositeObjectSinkAdapter.java:460)
>>  at
>> org.drools.reteoo.CompositeObjectSinkAdapter.propagateModifyObject(CompositeObjectSinkAdapter.java:428)
>> at org.drools.reteoo.ObjectTypeNode.modifyObject(ObjectTypeNode.java:263)
>>  at
>> org.drools.reteoo.EntryPointNode.modifyObject(EntryPointNode.java:172)
>> at
>> org.drools.common.AbstractWorkingMemory.update(AbstractWorkingMemory.java:1442)
>>  at
>> org.drools.common.AbstractWorkingMemory.update(AbstractWorkingMemory.java:1349)
>> at
>> org.drools.base.DefaultKnowledgeHelper.update(DefaultKnowledgeHelper.java:183)
>>  at
>> org.drools.base.DefaultKnowledgeHelper.update(DefaultKnowledgeHelper.java:196)
>> at
>> es.simcasva.alarmas.rules.Rule_Test_Negativo_Alarma_Acceso_Portal_Ubicacion_UM_0.defaultConsequence(Rule_Test_Negativo_Alarma_Acceso_Portal_Ubicacion_UM_0.java:18)
>>  at
>> es.simcasva.alarmas.rules.Rule_Test_Negativo_Alarma_Acceso_Portal_Ubicacion_UM_0DefaultConsequenceInvoker.evaluate(Rule_Test_Negativo_Alarma_Acceso_Portal_Ubicacion_UM_0DefaultConsequenceInvoker.java:44)
>>  at
>> org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:917)
>> at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:856)
>>  at org.drools.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1071)
>> at
>> org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:785)
>>  at
>> org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:751)
>> at
>> org.drools.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:218)
>>
>> I've been trying to find the problem, and found a strange interaction
>> between three rules that makes the null pointer to appear. The alarm system
>> has many rules now and it is difficult to simplify the scenario, so I just
>> would like to know what is the funcion of AccumulateNode object in order to
>> have an idea of the NullPointerException possible cause.
>>
>> Can anyone help me?
>>
>> Thank you in advance for your time.
>>
>> Regards,
>>
>> Manuel Ortiz.
>>
>>
>> _______________________________________________
>> rules-users mailing list
>> rules-users at lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/rules-users
>>
>>
>
>
> --
>  - CTO @ http://www.plugtree.com
>  - MyJourney @ http://salaboy.wordpress.com
>  - Co-Founder @ http://www.jbug.com.ar
>
>  - Salatino "Salaboy" Mauricio -
>
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