ActivityEdge semantics



Date view Thread view Subject view Author view Attachment view

From: John Daniels (jd@syntropy.co.uk)
Date: Mon 08 Sep 2003 - 08:23:38 BST


Dear UMLers,

I have a question about the semantics of multiple transitions (edges)
leaving an action in an activity diagram.

In UML 1.5, drawing an action with multiple outgoing transitions
implied a decision point, as explained in the spec:

----
A decision may be shown by labeling multiple output
transitions of an action with different guard conditions.
----

However, my brief reading of the UML 2 "final draft" superstructure
spec seems to suggest that the meaning has changed:

----
[4] When completed, an action execution offers object tokens on all
its output pins and control tokens on all its outgoing control edges
(implicit fork), and it terminates. Exceptions to this are listed
below. The output tokens are now available to satisfy the control or
object flow prerequisites for other action executions.
----

I take this to mean that drawing multiple outgoing "transitions" from
an action in UML 2 implies forking, not decision branching. Am I
right?

All the best,

--John

John Daniels

Date view Thread view Subject view Author view Attachment view