Control Flows Between Activities

[Mudar Bahri]

If Control Flows are not allowed between activities in v16.1, why the online documentation still contains examples that contains all types of prohibited connections?
https://sparxsystems.com/enterprise_architect_user_guide/16.1/modeling_languages/activitydiagram.html

This is super confusing for people who fail to create the connections, and refer to help to see all connections that they cannot do in one example!

Please update that diagram

[Geert Bellekens]

Hi M.B,


This is a user-forum. So you are essentially talking to your fellow users.
We don't have the power to update Sparx documentation.

You can report this as a bug using the link on the bottom of the page.

Geert

[Mudar Bahri]

Thanks, I have reported that to support. Sorry for posting in the wrong place. You can remove the post if you prefer.

[Geert Bellekens]

It's not the wrong place, but maybe the wrong expectations.

It's good to share this with the other users, and maybe get a discussion going. It' won't get things changed though.

Geert

[Mudar Bahri]

I received this from support today:

"Thank you for your report.

The issue has been confirmed and will be investigated further by our development team.

The notation for both Activity and Action is a rounded rectangle, so the elements in the diagram you linked to could be either. (I am sure that this ambiguity was wholly intentional from the authors of UML). However, as the elements appear to be the default size of an Activity element as created by EA, I can see that the diagram could be confusing, and we will change it.

Best regards,

Sparx Systems Pty Ltd"

[Modesto Vega]

I now remember having a similar discussion in this forum. With the rounded rectangle notation is virtually impossible to distinguish activities from actions. Control flows are permitted between actions, between actions and start/end points, and between actions and decision points. But the same does not apply to activities.

In the end, we use legends to change the fill colour of actions and avoid the confusion created by the notation.

Having said this, I still have trouble understanding what an activity is supposed to represent in UML.

[qwerty]

An activity is a container for actions. It's rather obvious that taking the same shape for both was not a good choice taken by OMG.

q.

[Geert Bellekens]

Having said this, I still have trouble understanding what an activity is supposed to represent in UML.

Usually people understand if you compare it with statemachines and states

Activity => StateMachine
Action => State

Geert

[Modesto Vega]

Usually people understand if you compare it with statemachines and states

Activity => StateMachine
Action => State

Geert

Well Sparx Systems does not help with the documentation in https://sparxsystems.com/resources/tutorials/uml2/state-diagram.html does not explain what boxes represent actions and which ones represent activities. Also, this page seems to imply that a state machine and an activity diagram are the same thing, when they are not, this is the activity diagram page https://sparxsystems.com/enterprise_architect_user_guide/16.1/guide_books/tools_ba_uml_activity_diagram.html.

[qwerty]

Sparx is not to blame. OMG made action, activity and state/machine appear as rounded rectangle. You only know be context which is which. Or you are able to inspect the model along with the metataypes.

w.

[Eve]

Well Sparx Systems does not help with the documentation in https://sparxsystems.com/resources/tutorials/uml2/state-diagram.html does not explain what boxes represent actions and which ones represent activities. Also, this page seems to imply that a state machine and an activity diagram are the same thing, when they are not

On that page every rounded rect is a state.

The word activity is not used at all, and the word action is only used to describe a transition effect and the entry/doActivity/exit properties of a state. I can't see why you read the implication that a state machine and an activity diagram are the same thing.

this is the activity diagram page https://sparxsystems.com/enterprise_architect_user_guide/16.1/guide_books/tools_ba_uml_activity_diagram.html.

That's a very high level summary of an activity diagram. It's not a tutorial for how to use Activity diagrams. This is still isn't as complete as you would like, but it's at least describing the items in the toolbox.
https://sparxsystems.com/enterprise_architect_user_guide/16.1/modeling_languages/activitydiagram.html

[Geert Bellekens]

https://sparxsystems.com/enterprise_architect_user_guide/16.1/modeling_languages/activitydiagram.html

The problem with this link is that is shows an invalid Activity Diagram. The diagram contains Activities connected with control flows (which has always been illegal, but only recently is being stopped by EA)

Now you could argue (as Sparx Support did) that the notation of Actions and Activities on a diagram is similar, and that these all might be Actions after all, but that is false.

How do I know? The difference between Activities and Actions (except for their default size) is the alignment of the name.
Actions have a centered name, Activities have a name that is aligned to the top.

In this case the elements on the diagram are clearly Activities (based on the alignment of the name), and thus the diagram is an invalid example of an Activity Diagram.

Geert

[qwerty]

Eagle's eye, but only true when relating to EA. AFAIR there is nothing in the UML specs that states the alignment of labels. Though being in the EA docs it's likely true what you say.

q.

[Modesto Vega]

[SNIP]
The word activity is not used at all, and the word action is only used to describe a transition effect and the entry/doActivity/exit properties of a state. I can't see why you read the implication that a state machine and an activity diagram are the same thing.
[...]
That's a very high level summary of an activity diagram. It's not a tutorial for how to use Activity diagrams. This is still isn't as complete as you would like, but it's at least describing the items in the toolbox.
https://sparxsystems.com/enterprise_architect_user_guide/16.1/modeling_languages/activitydiagram.html

Eve, you are reinforcing the point I was trying to make, the problem with both documentation pages is that mostly don't explain what elements are included and required Geert's eagle eyes to spot that actions have a different name alignment and, therefore, the diagram is incorrect.

The reason why I like ArchiMate is because it does not have the ambiguity introduced by OMG in the specification. But Sparx Systems could have done better to help differentiate between activities and actions - e.g., a thicker like or a different fill colour - and correct the documentation.