FormKey for Message based Start Events
Matthias Brenner
The process itself my provide several start events:
- start new artifact
A new artifact has to be entered with all it's properties - modify existing artifact
An existing artifact has to be selected
To be able to address multiple start events in the process, they are modeled as message start events.
As you see, there are reasons for different GUI depending on the start event. The remaining process can be the same.
How can I retrieve the form key from the start event?
First I tried to set up a parse listener for start events and check, whether there is a form key. If it is defined I could present the GUI. Unfortunately I could not find any entries in the API to retrieve the formKey. I found it on the XML elements. In the next step I looked through the code of the parser and recognized, that the parser does only parse the formKey for the user task and leaves my alone for the start event (hope that I'm wrong).
I asked Daniel how to retrieve the formKey. I said, I could use the method org.camunda.bpm.engine.FormService.getStartFormKey(String processDefinitionId). This seems to work only for ordinary start events. Since my problem case requires multiple start events, I use message based start events.
Please provide me some information how I can retrieve the form key for a message based start event.
Philipp Ossler
Matthias Brenner
I implemented a parse handler for the start event. I lookup the form key in the DOM tree. My implementation is working. But it is not nice.
From my point of view: The message start event is provided with a form key, but no possibility to access it via the Camunda APIs. So I think Camunda is not consistent at this point. You allow to enter the form key (modeller), but there is no help to extract it (engine).
In the moment I understood, that there is no Camunda support, I was able to write my own implementation. But I think Camunda should be consistent. If the start event is message based, do not allow to provide a form key (bad for me, because I use it) or provide the functionality in the engine to access the form key (would be very nice ;-) ).
Thanks for the code explanation. Now I understand how the form key is accessed.
Another question to the extension elements. If I would implement such an extension element for the message based start event, it would be possible for me to extract the form key during a execution listener?
Kind regards
Matthias
Philipp Ossler
BpmnModelInstance bpmnModelInstance = repositoryService.getBpmnModelInstance(processDefinitionId);
Collection<StartEvent> startEvents = bpmnModelInstance.getModelElementsByType(StartEvent.class);StartEvent startEvent = startEvents.iterator().next();String formKey = startEvent.getCamundaFormKey();