Conditional Expression in Intermidiate Catching event

[vgaur]

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.

I posted similar question os stack overflow https://stackoverflow.com/questions/60350138/signalexpression-in-activiti-6-0-intermediate-catching-...

Can someone help.

[EddieMay]

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, 

[vgaur · Accepted solution]

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.

1. 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();
         }
       });

2. 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);
                     }
   
                   };
                 }
   
               })

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

Thanks

-Vishal

[EddieMay]

Hi @vgaur,

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

Kind regards,