Conditional Expression in Intermidiate Catching event

vgaur — Sat, 22 Feb 2020 08:00:38 GMT

I am trying to use intermididate catching event in my process definition, but only want to signal it based on condition. I can see signalExpression is there inside catching event but bpmn modelere is not allowing me to use this.

Can someone help.

Re: Conditional Expression in Intermidiate Catching event

EddieMay — Mon, 24 Feb 2020 09:26:44 GMT

Hi @vgaur,

I see on Stack that someone chipped in - looks like you have resolved your issue? If so, it would be great if you could update this post with how you resolved your problem.

Many thanks,

Re: Conditional Expression in Intermidiate Catching event

vgaur — Fri, 28 Feb 2020 15:05:07 GMT

Hi,

Clearly the signal expression is not a standard BPMN and is an extension. To make it work this is what I had to do.

Had to extend CatchEventXMLConverter and add it in BpmnXMLConverter.

 BpmnXMLConverter.addConverter(new CatchEventXMLConverter() {
      @Override
      protected void writeSignalDefinition(Event parentEvent,
          SignalEventDefinition signalDefinition, XMLStreamWriter xtw) throws Exception {
        xtw.writeStartElement(ELEMENT_EVENT_SIGNALDEFINITION);
        writeDefaultAttribute("activiti:"+ATTRIBUTE_SIGNAL_EXPRESSION, signalDefinition.getSignalExpression(), xtw);
        if (parentEvent instanceof ThrowEvent && signalDefinition.isAsync()) {
          BpmnXMLUtil.writeQualifiedAttribute(ATTRIBUTE_ACTIVITY_ASYNCHRONOUS, "true", xtw);
        }
        boolean didWriteExtensionStartElement =
            BpmnXMLUtil.writeExtensionElements(signalDefinition, false, xtw);
        if (didWriteExtensionStartElement) {
          xtw.writeEndElement();
        }
        xtw.writeEndElement();
      }
    });

Had to extend IntermediateCatchSignalEventActivityBehavior and register it process engine configuration.

getProcessEngineConfiguration())
            .setActivityBehaviorFactory(new DefaultActivityBehaviorFactory() {
              @Override
              public IntermediateCatchSignalEventActivityBehavior createIntermediateCatchSignalEventActivityBehavior(
                  IntermediateCatchEvent intermediateCatchEvent,
                  SignalEventDefinition signalEventDefinition, Signal signal) {


                return new IntermediateCatchSignalEventActivityBehavior(signalEventDefinition,
                    signal) {
                
                  private static final long serialVersionUID = 1L;

                  @Override
                  public void execute(DelegateExecution execution) {
                    CommandContext commandContext = Context.getCommandContext();
                    ExecutionEntity executionEntity = (ExecutionEntity) execution;

                    String signalName = null;

                    Expression signalExpression =
                        commandContext.getProcessEngineConfiguration().getExpressionManager()
                            .createExpression(signalEventDefinition.getSignalExpression());
                    signalName = signalExpression.getValue(execution).toString();


                    commandContext.getEventSubscriptionEntityManager().insertSignalEvent(signalName,
                        signal, executionEntity);
                  }

                };
              }

            })

I removed signalRef completely But you can tweak the code and use both flavour.

Thanks

-Vishal

Re: Conditional Expression in Intermidiate Catching event

EddieMay — Mon, 02 Mar 2020 09:39:09 GMT

Hi @vgaur,

Thanks for posting your solution - really helpful to other hub members.

Kind regards,

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