Display the same Activity twice on a BPMN diagram

[Guillaume]

Hi

Is there any way in EA to show twice the same element on the same diagram? Could EA support it e.g. by allowing this if we enable an option in the diagram properties?

I currently have a business process modelled in a BPMN2 diagram. I need to use at 2 separate places the same activity.
I'm currently duplicating it because using the same will make my diagram difficult to read & understand.

Could we use references or something similar? I realise this is not without impacts

[Geert Bellekens]

Guillaume,

You can't because you should be using Actions that call an Activity and not Activities.
See my best practice about that: UML Best Practice: There are no Activities on an Activity Diagram

Geert

[Guillaume]

Hi Geert,

This is what I initially suggested to my colleague but actions of type "call behaviour" are specific to UML activity diagram. If you use BPMN, actions aren't available (and I'd rather not mix UML with BPMN).
Hence the need for this feature of showing the same element twice, but I see the argument against it.

thanks

[Ian Mitchell]

Looking at Geerts excellent link (there's lots of good stuff here Geert!) it looks like he's cheated a little: going from Activities to Actions doesn't solve the problem: Geert's diagram looks to have created some instances of the Actions, and put two instances on the diagram. This works in the diagram, and a trick I have used myself if I'm in a hurry, but I'm not sure it's generally a good idea.

@Guillaume - in your case, the only solution is to split the diagram into some smaller ones, so that each one only has one instance of the Activity. This is OK in BPMN, as you can just add Intermediate Events, then have them trigger the multi-use Activity, then carry-on.
Messy, but gets around the problem. Smaller diagrams MAY make your process easier to understand :-)

In this case, the restriction of no-multiple-elements is a pain, though the thought of relaxing it would cause so much more bad modelling, that personally I'd rather live with the occasional pain and keep the rule.

[philchudley]

Picky and pedantic mode on

Geert is correct in his use of actions, in his example. He has two separate Action elements referring to the[highlight] same Activity[/highlight]. This is shown in the call behaviour Action as a Behavioural Classifier which prefixes the Activity name by a colon. This appears as if it is two object instances but it isn't.

Picky mode off

Still doesn't solve the problem with BPMN though, and separate diagrams is certainly a work around.

Cheers

Phil

[Ian Mitchell]

I'm learning all the time here...
So I see now in the EA database what Geert has done with EA, as explained by Phil.
But in terms that one might use with, say, a delegate on a course, what does the idea of a 'Behavioural Classifier' mean? Have we just created a proxy for an 'instance' of the Activity, or is this just a work-around for the Sparx restriction, or does this have some basis in UML that might need explaining?
"Behavioural Classifier" has always been a bit of a closed-book to me. I NEED enlightening!

[Eve]

Call Behavior actions is not an EA kludge, it's the correct way to model in UML. If the code world is clearer to you, think of an Activity as an Operation. You don't directly make relationships that say this operation comes before this operation (unless perhaps you're doing aspect oriented programming)

What you do is define one operation to be a series of actions and decisions. One thing that an action can be is to call another operation (activity).

The same applies to StateMachines, where you don't put a state machine on a state machine diagram, but if you want a re-useable substate definition you can create a submachine state, and reference another state machine.

This discussion isn't about UML however, but the same rule applies. Just the terminology changes. The re-useable behavior type in BPMN is a Process (known in EA as Business Process) or potentially a GlobalTask. An Activity in BPMN is equivalent to an Action in UML.

To re-use behavior in BPMN you create a CallActivity (in EA set the isACalledActivity tag to true and assign an element to the calledActivity tagged value)

[Graham_Moir]

That is very useful Simon, thank you!