ProcessEventListener doesn't set process variable

[Jérôme Gisson]

Hi,

I post this question in jBPM Development forum but maybe I'm wrong, so post it again here.

In a spring-boot application (jBPM 6.4 embedded), I create a ProcessEventListener to reload an object from an external database (NoSQL) during my process.

I use the beforeNodeTriggered method to set or update the variable with the following code:

  WorkflowProcessInstanceImpl pi = (WorkflowProcessInstanceImpl) event.getProcessInstance();
  WorkflowCase wfCase = new WorkflowCase();
  wfCase.setCaseId("case-id");
  wfCase.setCaseOrigin("case origin");
  wfCase.setServiceLevel("level");
  pi.setVariable("wfCase", wfCase);

No error occur during the ProcessEventListener, but when I try to use the "wfCase" variable later in a gateway, the variable is not up to date (I got a NPE because the wfCase is null).

Is it the good way to reload process variable from external database ?
If yes, how I can set the process variable ?

Regards,
Jérôme.

[Maciej Swiderski]

I'd recommend to use pluggable variable persistence strategies - see this article http://mswiderski.blogspot.se/2014/02/jbpm-6-store-your-process-variables.html

if you want to stick to process event listener you could try to use following code:
VariableScopeInstance variableScopeInstance = (VariableScopeInstance) ((ProcessInstance) event.getProcessInstance()).getContextInstance(VariableScope.VARIABLE_SCOPE);
if (variableScopeInstance != null) {
    variableScopeInstance.setVariable(variableName, VALUE);
}

Maciej

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[Jérôme Gisson]

Thank you for your suggestion about pluggable variable persistence, I keep it in mind :)

But for now, I try with the process event listener approach and I tests your code with the same result.
I also try this, with the same result:
  KieSession ksession = (KieSession) event.getKieRuntime();

  WorkflowProcessInstanceImpl pi = (WorkflowProcessInstanceImpl) event.getProcessInstance();

  Map<String, Object> variables = new HashMap<String, Object>(1);
  variables.put(VAR_WF_CASE, wfCase);
  ksession.execute(new SetProcessInstanceVariablesCommand(pi.getId(), variables));

So I try to set my variable in a ScriptTask at the begin of my process:
  org.tests.model.WorkflowCase scriptCase = new org.tests.model.WorkflowCase();
  scriptCase.setCaseId("case-id");
  scriptCase.setCaseOrigin("case origin");
  scriptCase.setServiceLevel("level");
  kcontext.setVariable("wfCase", scriptCase);

Each time the variable wfCase is null.

The org.tests.model.WorkflowCase class is a POJO. jBPM can persist it in process variable ?

Regards,
Jérôme.

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[Maciej Swiderski]

you would have to share your process, listener and the way you invoke it. It’s been used quite a lot that way so I am quite sure it works

Maciej

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[Jérôme Gisson]

Hi,

I attach a zip file with a kmodule project (Maven 3, jBPM 6.4).
It includes the bpmn file, service task class, the process event listener and a jUnit test based on JbpmJUnitBaseTestCase class use to test the process.

When i run the junit class, I got the follow exception:

org.jbpm.workflow.instance.WorkflowRuntimeException: [subscription:1 - Load Case:4] -- [subscription:1 - Case Partages / Manuel:5] -- Exception when trying to evaluate constraint Partages in split Case Partages / Manuel
    at org.jbpm.workflow.instance.node.WorkItemNodeInstance.internalTrigger(WorkItemNodeInstance.java:149)
    at org.jbpm.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:173)
    at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerNodeInstance(NodeInstanceImpl.java:366)
    at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerCompleted(NodeInstanceImpl.java:325)
    at org.jbpm.workflow.instance.node.StartNodeInstance.triggerCompleted(StartNodeInstance.java:73)
    at org.jbpm.workflow.instance.node.StartNodeInstance.internalTrigger(StartNodeInstance.java:44)
    at org.jbpm.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:173)
    at org.jbpm.ruleflow.instance.RuleFlowProcessInstance.internalStart(RuleFlowProcessInstance.java:35)
    at org.jbpm.process.instance.impl.ProcessInstanceImpl.start(ProcessInstanceImpl.java:236)
    at org.jbpm.workflow.instance.impl.WorkflowProcessInstanceImpl.start(WorkflowProcessInstanceImpl.java:439)
    at org.jbpm.process.instance.ProcessRuntimeImpl.startProcessInstance(ProcessRuntimeImpl.java:208)
    at org.jbpm.process.instance.ProcessRuntimeImpl.startProcess(ProcessRuntimeImpl.java:191)
    at org.jbpm.process.instance.ProcessRuntimeImpl.startProcess(ProcessRuntimeImpl.java:183)
    at org.drools.core.impl.StatefulKnowledgeSessionImpl.startProcess(StatefulKnowledgeSessionImpl.java:1807)
    at org.drools.core.command.runtime.process.StartProcessCommand.execute(StartProcessCommand.java:122)
    at org.drools.core.command.runtime.process.StartProcessCommand.execute(StartProcessCommand.java:40)
    at org.drools.core.command.impl.DefaultCommandService.execute(DefaultCommandService.java:36)
    at org.drools.core.command.impl.AbstractInterceptor.executeNext(AbstractInterceptor.java:41)
    at org.drools.persistence.SingleSessionCommandService$TransactionInterceptor.execute(SingleSessionCommandService.java:592)
    at org.drools.core.command.impl.AbstractInterceptor.executeNext(AbstractInterceptor.java:41)
    at org.drools.persistence.jpa.OptimisticLockRetryInterceptor.execute(OptimisticLockRetryInterceptor.java:82)
    at org.drools.core.command.impl.AbstractInterceptor.executeNext(AbstractInterceptor.java:41)
    at org.drools.persistence.jta.TransactionLockInterceptor.execute(TransactionLockInterceptor.java:73)
    at org.drools.persistence.SingleSessionCommandService.execute(SingleSessionCommandService.java:385)
    at org.drools.core.command.impl.CommandBasedStatefulKnowledgeSession.startProcess(CommandBasedStatefulKnowledgeSession.java:256)
    at org.tests.bpmn.SubscriptionProcessTest.startProcessForManualCase(SubscriptionProcessTest.java:76)
    at org.tests.bpmn.SubscriptionProcessTest.testCaseComplete(SubscriptionProcessTest.java:54)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
Caused by: org.jbpm.workflow.instance.WorkflowRuntimeException: [subscription:1 - Case Partages / Manuel:5] -- Exception when trying to evaluate constraint Partages in split Case Partages / Manuel
    at org.jbpm.workflow.instance.node.SplitInstance.internalTrigger(SplitInstance.java:67)
    at org.jbpm.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:173)
    at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerNodeInstance(NodeInstanceImpl.java:366)
    at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerCompleted(NodeInstanceImpl.java:325)
    at org.jbpm.workflow.instance.impl.ExtendedNodeInstanceImpl.triggerCompleted(ExtendedNodeInstanceImpl.java:44)
    at org.jbpm.workflow.instance.node.StateBasedNodeInstance.triggerCompleted(StateBasedNodeInstance.java:341)
    at org.jbpm.workflow.instance.node.StateBasedNodeInstance.triggerCompleted(StateBasedNodeInstance.java:318)
    at org.jbpm.workflow.instance.node.WorkItemNodeInstance.triggerCompleted(WorkItemNodeInstance.java:323)
    at org.jbpm.workflow.instance.node.WorkItemNodeInstance.workItemCompleted(WorkItemNodeInstance.java:385)
    at org.jbpm.workflow.instance.node.WorkItemNodeInstance.signalEvent(WorkItemNodeInstance.java:361)
    at org.jbpm.workflow.instance.impl.WorkflowProcessInstanceImpl.signalEvent(WorkflowProcessInstanceImpl.java:484)
    at org.drools.persistence.jpa.processinstance.JPAWorkItemManager.completeWorkItem(JPAWorkItemManager.java:147)
    at org.jbpm.process.workitem.bpmn2.ServiceTaskHandler.executeJavaWorkItem(ServiceTaskHandler.java:261)
    at org.jbpm.process.workitem.bpmn2.ServiceTaskHandler.executeWorkItem(ServiceTaskHandler.java:175)
    at org.drools.persistence.jpa.processinstance.JPAWorkItemManager.internalExecuteWorkItem(JPAWorkItemManager.java:69)
    at org.jbpm.workflow.instance.node.WorkItemNodeInstance.internalTrigger(WorkItemNodeInstance.java:138)
    ... 51 more
Caused by: java.lang.RuntimeException: Exception when trying to evaluate constraint Partages in split Case Partages / Manuel
    at org.jbpm.workflow.instance.node.SplitInstance.executeStrategy(SplitInstance.java:93)
    at org.jbpm.workflow.instance.node.SplitInstance.internalTrigger(SplitInstance.java:63)
    ... 66 more
Caused by: java.lang.RuntimeException: unable to execute ReturnValueEvaluator:
    at org.jbpm.process.instance.impl.ReturnValueConstraintEvaluator.evaluate(ReturnValueConstraintEvaluator.java:131)
    at org.jbpm.workflow.instance.node.SplitInstance.executeStrategy(SplitInstance.java:86)
    ... 67 more
Caused by: java.lang.NullPointerException
    at org.tests.Process_org$u46$tests$u46$subscription341203229.returnValueEvaluator2(Process_org$u46$tests$u46$subscription341203229.java:21)
    at org.tests.Process_org$u46$tests$u46$subscription341203229ReturnValueEvaluator2Invoker.evaluate(Process_org$u46$tests$u46$subscription341203229ReturnValueEvaluator2Invoker.java:15)
    at org.jbpm.process.instance.impl.ReturnValueConstraintEvaluator.evaluate(ReturnValueConstraintEvaluator.java:129)
    ... 68 more

Let me know if you can reproduice this issue.

Regards,
Jérôme.

[Maciej Swiderski]

Problem is not the listener as that work as expected but your service task “Load Case” as this has defined output mapping which overriddes the value set by the listener. So remove all mapping of the service task if it should not set it and then all works as expected.

Maciej

To view this discussion on the web visit https://groups.google.com/d/msgid/jbpm-usage/16481116-40c5-4ca3-9d15-7128a687cb39%40googlegroups.com.

For more options, visit https://groups.google.com/d/optout.

<jbpm-processeventlistener.zip>

[Jérôme Gisson]

Hi,

Thanks a lot for you reply it works after remove the output mapping :)

I use Bpmn2 Diagram Editor to edit my process and the "Output Data Mapping" section was empty. So I open the process with BPMN Process Editor and I saw the mapping in "Result Mapping" section.
What editor do you recommend ? Is Bpmn2 Diagram Editor stable ?

Regards,
Jérôme.

[Maciej Swiderski]

glad to hear it worked as expected. I'd say BPMN2 editor should be used as it's being developed. If you prefer web based tooling the web designer in workbench is a good choice too.

Maciej

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