I find the implementation of call activity in ARIS a bit exotic. I would be happy to learn from the community how do you go about it. The occurrence/definition concept and assignment/selectionOfGlobalActivity pose some challenges.
1. My first question is do you use definition or occurrence copies?
My preference is for definition because call activities calling the same global activity from different processes can bring different input. But that's a high-maintenance option and a double work when modelling and changing. Additionally having deffintion copies with the same Name poses other problems.
Using occurrence copies seems easier but is it BPMN2-complient, how do you know who is calling (without checking in which model is the occurrence) and then what about execution?
2. The second question is related to selection of global activity. What is now allowed is to select a task or a collaboration diagram but not the most common IMO thing - the process diagram. Do you also find it strange and what do you do about it.
I few other things related to BPMN2-in-ARIS have been bugging me the last couple of years, but let's not bee greedy.
The call activity (or call subprocess) is a step that is always (!) the same wherever you use it - e.g. in regards to inputs. That means that you should use an occurrence when these criteria are met ... having said that, in reality this might not be so easy to "enforce".
My suggestion would be to use occurrence copies and put some (manual) governance around it. This will allow you to model BPMN-compliant call subprocesses, which keep their assignments.
In general the usage of call activities/subprocesses is kind of akward and does not match the definition/occurrence concept perfectly. Having said that, the use of definition copies would be the least desirable way to model due to the reasons you mention above.
Roland,
There are some cases where occurence copies cannot be used. Here's a real-life example: A globas sub-process is called by activities A and B which belong to processes P1{A} and P2{B} respectively. The subprocess is related to tasks perfromed for creating a new ARIS database and changing some configurations such as user groups, based form the input of the calling element. However, the first Task in that subprocess is to create the database from a template, and when called by A, it shoud be a template with LDAP configured, when called by B it should be from a temaplate configured not to use external authorisation system. In this case A and B have no other chance but the be deffinition copies. And this structure is, I believe, fully complient with the specification:
"A Call Activity can override properties and attributes of the element being called, potentially changing the behavior of the called element based on the calling context." (p. 185)
