(responding to Eric Tarkington)
> I haven't done enough with activity diagrams, but here's > how it looks to me: > > The initial activity executes in 1 "tick" so the multiple transitions > out of it are simulaneous. A synchronization bar in the diagram > is harmless but redundant. > > If you have an initial state, instead of an activity, the state can > use an indeterminate number of ticks (including 0) between the > transitions, so the parallel threads may be *launched* > asynchronously, and a synchronization bar is very significant. Well I don't agree, but OTOH, I can't say you're wrong. And therein lies the problem - the notation can be ambiguous; different interpretations are possible, and there seems to be no guidance on which is correct. (I have heard that UML 2.0 will clear up this ambiguity; I'm still wading through the documentation of 1.4 and hope to be finished by Christmas! ) What I _can_ say is that if one wants to say that the outgoing transitions are alternatives, it is possible to say this without ambiguity by putting a set of mutually exclusive guard conditions on the outgoing transitions. If OTOH one wants to say that the outgoing transitions are all to happen, possibly in parallel, then it is also possible to say this without ambiguity by using fork (and join) synchronisation bars. If one doesn't want to say at this stage which of the options are desired (I can't conceive of an example, but maybe others have better imaginations), then it _may_ be a valid approach to have multiple outgoing transitions without mutually exclusive guards. However, if anyone is about to take this approach, I recommend that they thoroughly document what it is that they are trying to say, because it is clear that different people will read the diagram in different ways. Paul Oldfield ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ www.aptprocess.com any opinions expressed herein are not necessarily those of Mentors of Cally or the Appropriate Process Movement ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ************************************************************************ * Rose Forum is a public venue for ideas and discussions. * For technical support, visit http://www.rational.com/support * * Post or Reply to: [EMAIL PROTECTED] * Subscription Requests: [EMAIL PROTECTED] * Archive of messages: * http://www.rational.com/support/usergroups/rose/rose_forum.jsp * Other Requests: [EMAIL PROTECTED] * * To unsubscribe from the list, please send email * To: [EMAIL PROTECTED] * Subject: <BLANK> * Body: unsubscribe rose_forum *************************************************************************
