Can't get simple demo of compensation to work

Flowable Engine
1

I’ve been attempting to understand how the compensation feature works with the bpmn model. I’ve reviewed the CompensateEventTest.testCompensateSubprocessWithUserTask model and replaced the user task with a service task with a simple system.out. I still can’t seem to get my compensation service task to be called. Here is the bpmn content:

  <process id="mailpieceExtractionProcess" isExecutable="true">
    <startEvent id="start"></startEvent>
    <subProcess id="scope" name="subProcess">
      <startEvent id="startevent1" name="Start"></startEvent>
      <endEvent id="endevent2" name="End"></endEvent>
      <serviceTask id="servicetask1" name="Service Task" activiti:class="prince.SimpleJavaDelegateTask"></serviceTask>
      <sequenceFlow id="flow4" sourceRef="startevent1" targetRef="servicetask1"></sequenceFlow>
      <boundaryEvent id="boundarycompensation1" name="Compensate" attachedToRef="servicetask1" cancelActivity="true">
        <compensateEventDefinition></compensateEventDefinition>
      </boundaryEvent>
      <serviceTask id="servicetask2" name="Service Task" isForCompensation="true" activiti:class="prince.SimpleJavaDelegate"></serviceTask>
      <sequenceFlow id="flow5" sourceRef="servicetask1" targetRef="endevent2"></sequenceFlow>
      <association id="association1" sourceRef="boundarycompensation1" targetRef="servicetask2" associationDirection="None"></association>
    </subProcess>
    <sequenceFlow id="flow1" sourceRef="start" targetRef="scope"></sequenceFlow>
    <endEvent id="endevent1" name="End"></endEvent>
    <intermediateThrowEvent id="compensationintermediatethrowevent1" name="CompensationThrowingEvent">
      <compensateEventDefinition activityRef="scope"></compensateEventDefinition>
    </intermediateThrowEvent>
    <sequenceFlow id="flow2" sourceRef="scope" targetRef="compensationintermediatethrowevent1"></sequenceFlow>
    <sequenceFlow id="flow3" sourceRef="compensationintermediatethrowevent1" targetRef="endevent1"></sequenceFlow>
  </process>

I’m just calling the process without variables and all I get is the system.out from my [non-compensating] service task. Is there something I’m missing or not understanding?

Essentially, I’m looking to get to the point where I can use a transaction subprocess where tasks can be compensated if an error occurs. My thought is that this would work nicely as a rollback.

2

Ok, I’ve made some progress and think I might understand my issue better. It seems that I can’t call a Compensation Throwing Event from an Error Boundary Event? Is that right?

Basically, I’m just trying to catch any BpmnError that I may have thrown and then initiate a compensation to rollback any actions that previously occurred. Is this possible?

3

Ok, nevermind. I see now how this compensation works. I must have missed the explanation in the documentation. Only completed tasks can be compensated. Therefore, the task that has the error must perform its own clean-up from wherever it failed, then throw the bpmnerror to have other completed tasks compensated.

With only having 1 task that threw a bpmnerror to attempt to see it get compensated doesn’t work. Once must test with a task that will complete then have the second task fail to see the first task get compensated.