Activation of discretionary items and milestones in CMMN

Camunda 7 Topics Discussion & Questions
1

Hi there,
I have a problem understanding when certain PlanItems are activated in Camunda or not. We are currently building a ACM GUI to provide a proper UI for case workers based on the CattleCrew Demo by Opitz. We are using this case here as a demo

SCHub_CaseUI_Model.png1252×875 114 KB

We are using the REST API to get the available activities. However, the available activities don’t contain the discretionary HumanTask “Request additional requirement details”.

Question 1) Why is that the case? From my understanding discretionary items should be startable any time by the case worker. What REST call can I use to obtain discretionary items?

Question 2) The milestone “Specification complete” is not getting activated, although “Estimate effort” was completed. Why is that the case?

Question 3) In a previous version of the case definition I placed an exit sentry at the “create specification” stage so that it was sitting between the “Estimate effort” task and the milestone. In this case the milestone was completed right after the start of the case, before any human activity had occured! Why is that?

Question 4) Don’t you think that it would make more sense to set “manual activation” to false for stages by default? I found it kind of counter-intuitive having to explicitly set it to false in the case definition, because otherwise the tasks inside were not activated.

I’m attaching the cases XML file and the JSON response of /history/case-activity-instance for the id of the running instance

create_offer.cmmn (19.3 KB)

case_activities.json (9.9 KB)

Regards
René

2

Hi René,

Discretionary items are currently not supported by the case engine, in 1 you have an overview of supported elements.

The planItemOnPart connection between “Specification complete” and “Estimate effort” is crossing a stage boundary. This is also not supported by the engine. Therefore exists already a feature request 2.

Could you please share this previous version? Then it is easier to see what you mean and how the case engine behaves.

We fixed that behavior concerning the interpretation of the manual activation rule attribute of CMMN. This bugfix 3 is included in this release of camunda BPM 7.6.0-alpha3 (and will finally released in camunda BPM 7.6.0) and originates from an official bugfix 4 in the OMG CMMN standard.

Does it answer your questions?

Cheers,
Roman

3

Hi Roman,
thanks for the quick answers. I already assumed that there was missing support for something, but failed to notice the reference you stated. Are discretionary items on the roadmap yet? I think they are an important concept. What are the difficulties of implementing them?

Please find attached the old version of the CMMN case.
Regards
Renécreate_offer.cmmn (20.3 KB)

4

Hi René,

Thank you for sharing the previous version of the case.

Regarding your question:

The problem here is that, the entry criterion of the milestone references the exit criterion of the stage. This is currently not supported by the engine, so that this on part connection is ignored by the engine. As a consequence, the milestone gets completed when the case instance is started.

The other think that is also not support, that the plan item on part connection of the the exit criterion of the stage references a plan item which is inside the stage. Even if it does not look like but this plan item on part connection is crossing the stage boundary. This is also not supported (see my answer for Question 2).

Currently the discretionary items are not on the roadmap. It is not a matter of the difficulty to implement that, it is more about priority etc.

Cheers,
Roman

5