Catching exception in Service Task & Directing to User Task

[sankarts]

Using Java logic (not explicitly modeled in BPMN), e.g. catch a database persistence exception from a Service Task and direct it to a User Task (another sequence flow for the failure case). 

In this case, my plan is that the Service Task implements ActivityBehavior instead of Java Delegate.

Is this a viable and preferred approach? If not, please suggest alternatives. I am using Activiti 5.16.1.

Thanks in advance.

[sankarts]

It would be great, if someone well versed with Activiti can throw some light on my query. Thanks.

[trademak]

Hi,

Yes that's a viable approach. Another way would be to throw a BPMN error in that case and catch it with a boundary error event that connects to a user task. And it's also possible to use an exclusive gateway and check on a specific variable you set in the service task.

Best regards,

[sankarts]

Thanks for the quick response.

BTW, are you referring to the approach mentioned in the user guide for ActivityBehavior. If yes,

1) Is it possible without specifying exception and no-exception sequence flows in the workflow spec i.e. in .bpmn file? If yes, any pointers on this please?

Details extracted teh User Guide as below.
<xml>
serviceTask id="javaService"
  name="Java service invocation"
  activiti:class="org.activiti.ThrowsExceptionBehavior"
/serviceTask
   
sequenceFlow id="no-exception" sourceRef="javaService" targetRef="theEnd" /
sequenceFlow id="exception" sourceRef="javaService" targetRef="fixException" /

and the sample code snippet looks like
<java>
public class ThrowsExceptionBehavior implements ActivityBehavior {

  public void execute(ActivityExecution execution) throws Exception {
    String var = (String) execution.getVariable("var");

    PvmTransition transition = null;
    try {
      executeLogic(var);
      transition = execution.getActivity().findOutgoingTransition("no-exception");
    } catch (Exception e) {
      transition = execution.getActivity().findOutgoingTransition("exception");
    }
    execution.take(transition);
  }
 
}
</java>

[jbarrez]

If I'm following you, that would need to be configured in your own Behaviour (and use eg Field injection to configure those)