Does a Control Token also traverse via an Object Flow

[BiSb]

Hi everyone,

I'm trying to create an Activity Diagram in EA and I thought an Object Flow in UML/SysML would also traverse an Control Token, but when I try to manual simulate an Activity, it always stops if there is only an Object Flow between two Actions.

Can someone please explain and/or tell me, if this is correct?

Greetings
Sebastian

[qwerty]

P. 372 of UML 2.5 says

Tokens are not explicitly modeled in an Activity, but are used for describing the execution of an Activity. An object token is a container for a value that flows over ObjectFlow edges [...]. An object token with no value in it is called a null token. A control token affects execution of ActivityNodes, but does not carry any data, and flows only over ControlFlow edges. Each token is distinct from any other, even if it contains the same value as another.

So yes, there is a token sent over to control the flow. You send it explicitely over a pin from one action to another. And: not token no start of execution.

q.

[BiSb]

Thank you very much, so just for confirmation, because your quote contains more information:

Control Token only traverse over Control Flows and not over Object Flows?

Greetings
Sebastian

[qwerty]

In UML both have the same rendering (unlike SysML), but OT will only travel via ObjectFlow, not ControlFlow. So your model should be precise (e.g. if you intend to simulate something).

q.

[BiSb]

Understood and sorry to ask again, but do Control Token travel over Object Flows?

Greetings
Sebastian

[qwerty]

No, they have their private highway too. Via ControlFlow.

q.

[BiSb]

Thank your very much, especially for the clarification.

Greetings
Sebastian

[qwerty]

IIRC there's an option (somewhere in EA's option jungle) to render control flow as dashes lines (like in SysML). In our last project we used stereotyped O/C flow to have it that way. For a diagram reader you can't see the difference in plain UML. Only a machine (syntax check; automation) would stumble over wrong connectors. So, having them distinguishable was a requirement for us.

q.