Multi-Instance Call Activity

[Martin Schimak]

Hi all,

My apologies that I do not have a possibility right now to look into the docs deeply, and ask directly here: consider the case I have a call activity which sets some process variable and delivers it back to the parent process (camunda:out). Now, the call activity is marked to be multi-instance. Can I collect the camunda:out "results" back into a collection of results so that the parent process can move on with some more work on that collection? If yes, can you point me to an example how the bpmn (xml) fragment looks like?

Many thx,

Martin.

[Daniel Meyer]

Hi Martin,

I don't think this works out of the box. Interesting usecase, though.
Maybe we should think about allowing expressions / scripts for
"aggregating" the results of multi instance?

Cheers,
Daniel

[Bernd Rücker (camunda)]

Hi Martin.

At the moment I would add a listener to the end-event of the call activity
(should be multiple instance - or no? If not - I would add it to the
end-event of the called process) writing/aggregating the data by some Java
code. Should be easily doable in a quick test case. Let me know if you need
that urgently then I can maybe help out...

Cheers
BErnd


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[mailto:camunda-...@googlegroups.com] Im Auftrag von Daniel Meyer
Gesendet: Mittwoch, 22. Oktober 2014 08:36
An: camunda-...@googlegroups.com
Betreff: Re: [camunda-bpm-users] Multi-Instance Call Activity

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[thorben....@camunda.com]

Hi all,

Execution listeners in combination with multi-instance constructs are somewhat misbehaving at the moment, see ticket [1].

Cheers,
Thorben

[1] https://app.camunda.com/jira/browse/CAM-2787

[Martin Schimak]

Hi Daniel,

> Maybe we should think about allowing expressions / scripts for "aggregating" the results of multi instance?

While this might be a good idea for more advanced cases, I actually think there should be something more generic „out of the box“… a multi instance activity is meant to iterate over a collection of objects… hence we write e.g.

=> camunda:collection="${myService.resolveUsersForTask()}“
=> camunda:elementVariable=„assignee"

Now, with every object we can do something. Maybe we just want side effects, fair enough. But what if I want to „return" something back to the outer scope? What would that something normally be? I would argue: a collection of result objects. So I would actually expect to be able to write e.g.

=> camunda:resultVariable=„assigneeDocument“
=> camunda:resultCollection=„assigneeDocuments“

Inside every single execution of the multi instance I would be able (and expected) to actively set something into my resultVariable „assigneeDocument"… while the process engine then would take care of collecting these results into a new collection type variable „assigneeDocuments“ which can subsequently be seen by the surrounding scope. In case I need to aggregate that result now even more… I can actually just add a subsequent script task…

(In case this outer scope actually is a parent process, one needs to decide whether it would be necessary to declare the resultCollection as camunda:out, too, or not - I have no opinion about that right now)

Reasonable?
Feasible?
Martin.