Invalid update event trigger set for async message start event

[danielkelemen]

Environment (Required on creation)

7.19 and higher.

Description (Required on creation; please attach any relevant screenshots, stacktraces, log files, etc. to the ticket)

With https://github.com/camunda/camunda-bpm-platform/issues/2663 we automatically set the update event trigger flag for events containing messages. With async message start events this causes an error in the migration plan. The update event trigger flag should not be set for message start events.

Steps to reproduce (Required on creation)

• Create a process with a message start event, an intermediate message throw event, and an end message throw event and make them async before or after.
• Start a migration for this process.
• The cockpit migration plan will show an error because the message start event's update event trigger cannot be true.

Observed Behavior (Required on creation)

Cockpit migration shows an error.

Expected behavior (Required on creation)

Cockpit migration shows no error.

Root Cause (Required on prioritization)

We change the update event trigger flag for all activities with messageRef.

Solution Ideas

The update event trigger update logic needs to be adjusted so that it doesn't affect the message start events.

Hints

Links

• https://github.com/camunda/camunda-bpm-platform/issues/2663
• https://jira.camunda.com/browse/SUPPORT-16973

Breakdown

Dev2QA handover

• [ ] Does this ticket need a QA test and the testing goals are not clear from the description? Add a Dev2QA handover comment

[ThorbenLindhauer]

@danielkelemen please add the additional problem with the plan when migration is executed (see support case for details)

[danielkelemen]

Additionally, on the 7.19.1-ee, even after manually adjusting the mappings for async after message start events, the migration fails at the last step due to the same error about update event trigger. While the /validate request showed no error during the first step. The data sent to migrateAsync still contains the updateEventTrigger set to true.

[tasso94]

Problem

• Migration plans on creation are always valid when the matching activities are async (cf. https://jira.camunda.com/browse/CAM-5720).
• When generating migration plans, instructions for certain activities, like sync process instance start events or business rule tasks, are ignored by the generator, but when they are async, they are not.

Solution ideas

1. Frontend: Exclude process instance message start events from updateEventTrigger: true. Pros: relatively straightforward. Cons: other similar cases might remain uncovered (however, I cannot think of any).
2. Backend: Use report validation for assigning updateEventTrigger: false. Pros: would solve all situations, also unknown ones. Cons:
   • Report only contains an error message and no static error type or code, and the behavior might break when changing it in the future.
   • Instead of evaluating the error message, we could also add logic that optimistically tries to get rid of the validation error by changing the flag to false; getting this logic right and robust is quite some effort.
3. Backend: Don't generate instructions for async process instance start events. Pros: relatively simple Cons: this would break existing behavior; i.e., transition instance migration wouldn't be possible anymore.

4. Backend: Generate report containing updateEventTrigger:true/false Pros:

   • Only one single source of truth
   • Java and REST API users benefit from the feature as well

   Cons:

   • Higher effort (an abstract ruleset of when to define updateEventTrigger:true/false needs to be created)
   • Needs a new config flag to maintain backwards compatibility

Decision

Opting for solution # 1 since it is the simplest, given that async process instance message start event is the only case in which we want to disable the flag. If this assumption falsifies in the future, we can still build a more robust solution like # 4.

[danielkelemen]

Async Message Intermediate Throw Event and Message End Event can also cause this migration problem.

[tasso94]

@danielkelemen, I fixed the additional scenarios. Please review.

[tasso94]

Latest change does the following:

• Add updateEventTrigger to all flow nodes with MessageEventDefinition and ReceiveTask but not when they are of type:
  • EndEvent
  • IntermediateThrowEvent
  • Process instance start event

This covers the following cases:

• When process instance start event, IntermediateThrowEvent or EndEvent don't have async flags, the generator doesn't create instructions, so they don't end up having updateEventTrigger = true.
  • When adding these instructions manually, updateEventTrigger cannot be set to true since this would produce an error
• When process instance start event, IntermediateThrowEvent or EndEvent are included in the generator result, this is because they have async flags
  • updateEventTrigger cannot be set to true since this would produce an error

Comprehensive test process: event-trigger-process.bpmn.zip

[tasso94]

Handover DEV ↔️ QA

@gbetances089, I created a comprehensive BPMN Model to test the fixed behavior and to ensure no regressions were introduced for the existing behavior. But please feel free to play around and adjust it.

Comprehensive test process: event-trigger-process.bpmn.zip

[tasso94]

I forgot some braces and broke the logic:

!bo.$type === 'bpmn:EndEvent'
bo.$type -> true
!bo.$type -> false
false === ‘bpmn:EndEvent’
false === true -> false

[gbetances089]

Tested on Snapshot camunda-bpm-run-ee-7.20.0-20230614.175338-62 using the model provided and a few more to see it more in details.