Nicolas

2010/2/10 Glenn Macgregor <gmacgregor@pocketkings.ie>

Hi Nicolas,

Thanks for the response. The strange thing is I do not get this error when I run inside the debugger with the same facts. This made me believe it is a timing issue. I am using the latest stable drools - 5.0.1

Thanks

Glenn

From: rules-users-bounces@lists.jboss.org
To: Rules Users List
Sent: Wed Feb 10 18:18:57 2010
Subject: Re: [rules-users] CEP Error
Hi,
It says that the $param is null so $param.name() cannot be called
regards

Nicolas

2010/2/10 Glenn Macgregor <gmacgregor@pocketkings.ie>

Hi All,

I have a simple CEP test case which I am working through. I am currently getting a NullPointerException in the Consequence and have no idea why.

Rule:
rule "Param Update Event Rule"

      when

            $pue : ParameterUpdateEvent(name == "testParam2", $param : param) from entry-point "ParamUpdateStream"

      then

            #System.out.println("Param '" + $pue.getName() + "' has been updated to " + $pue.getValue());

            System.out.println("HERE!!! " + $param + " " + $param.name());

End

Exception & Debug:

OBJECT ASSERTED value:ie.PocketKings.SystemsManagement.Alerting.ParameterUpdateEvent@1265109 factId: 2

OBJECT RETRACTED value:ie.PocketKings.SystemsManagement.Alerting.ParameterUpdateEvent@1265109 factId: 2

OBJECT ASSERTED value:ie.PocketKings.SystemsManagement.Alerting.ParameterUpdateEvent@5e8d7d factId: 3

OBJECT RETRACTED value:ie.PocketKings.SystemsManagement.Alerting.ParameterUpdateEvent@5e8d7d factId: 3

ACTIVATION CREATED rule:Param Update Event Rule activationId:Param Update Event Rule [4, 0] declarations: $pue=ie.PocketKings.SystemsManagement.Alerting.ParameterUpdateEvent@19b4748(4); $param=ie.PocketKings.SystemsManagement.Alerting.Parameter@2431b9(4)

Exception in thread "Thread-3" BEFORE ACTIVATION FIRED rule:Param Update Event Rule activationId:Param Update Event Rule [4, 0] declarations: $pue=ie.PocketKings.SystemsManagement.Alerting.ParameterUpdateEvent@19b4748(4); $param=ie.PocketKings.SystemsManagement.Alerting.Parameter@2431b9(4)

OBJECT RETRACTED value:ie.PocketKings.SystemsManagement.Alerting.ParameterUpdateEvent@19b4748 factId: 4

OBJECT ASSERTED value:ie.PocketKings.SystemsManagement.Alerting.ParameterUpdateEvent@19b4748 factId: -1

org.drools.runtime.rule.ConsequenceException: java.lang.NullPointerException

      at org.drools.runtime.rule.impl.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:23)

      at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:943)

      at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:885)

      at org.drools.common.DefaultAgenda.fireUntilHalt(DefaultAgenda.java:1065)

      at org.drools.common.AbstractWorkingMemory.fireUntilHalt(AbstractWorkingMemory.java:701)

      at org.drools.common.AbstractWorkingMemory.fireUntilHalt(AbstractWorkingMemory.java:678)

      at org.drools.impl.StatefulKnowledgeSessionImpl.fireUntilHalt(StatefulKnowledgeSessionImpl.java:195)

      at ie.PocketKings.SystemsManagement.Alerting.SessionRunner.run(SessionRunner.java:13)

      at java.lang.Thread.run(Unknown Source)

Caused by: java.lang.NullPointerException

      at org.drools.base.ie.PocketKings.SystemsManagement.Alerting.ParameterUpdateEvent6011238$getParam.getValue(Unknown Source)

      at org.drools.base.ClassFieldReader.getValue(ClassFieldReader.java:91)

      at org.drools.rule.Declaration.getValue(Declaration.java:244)

      at ie.PocketKings.SystemsManagement.Alerting.Rule_Param_Update_Event_Rule_0ConsequenceInvoker.evaluate(Rule_Param_Update_Event_Rule_0ConsequenceInvoker.java:16)

      at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:934)

      ... 7 more

OBJECT ASSERTED value:ie.PocketKings.SystemsManagement.Alerting.ParameterUpdateEvent@19fdbcb factId: 5

Could it be that my Event object is getting destroyed before the consequence is run, is that what “OBJECT RETRACKED” means in this case?

Thanks

Glenn

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