(responding to Les)
<snip> >> (Paul) >> This information may go out of date with UML 2.0, but... >> >> As Activity diagrams are modified state diagrams, if >> there are multiple transitions coming out of one Activity >> state, then these are, AFAICS, alternatives. Thus only >> one of the activities would happen next, rather than all >> in parallel. OTOH, I agree that there is a good deal of >> ambiguity, and it would be safer explicitly to say what >> you mean. > <snip> > Thankyou to Paul, David, James and Martin (Fowler that > is) for helping to supply the answer to my poser. > I gather the consensus in my own simplistic terms, is that > transitions from an activity occur asynchronously, whereas > transitions from a fork occur in parallel. The latter is true, the former is probably true (but doesn't seem to have been nailed down for certain). > On the receiving end, a transtion into an activity causes that > activity to fire. If you wish for muliple activities to complete > before exercising a subsequent activity then you must use > a synchronization bar in order to wait for completion. It woulds appear so. > So, one more brief simple question, if a transition activates > an activity, and while that activity is exercising it receives a > subsequent transition, > > 1) does the activity reset and start again, > 2) does it complete before addressing the new stimulus, > 3) does it ignore the subsequent stimulus or > 4) is the behaviour customisable based upon the specification > of the activity? We must first question how such a precondition could arise. For each instantiation of an Activity Diagram, if the only way that we can get activities happening in parallel is via a fork, then this precondition can only occur between a fork and a join. If I were writing an activity diagram where there could be more than one transition into an activity after a fork, but without a join, then I would expect this occurrence to cause a new instantiation of the activity that may be proceeding in parallel with another instantiation of the activity from another thread derived from the fork. OTOH, what I expect may not be what other folk expect; the situation is a bit ambiguous for my purposes and I'd want to state clearly and unambiguously what I expect to happen. I guess UML is like any other language - you can write a sentence that is grammatically and syntactically correct, but it may still be nonsense. So my (tentative) answer is :- 5) It starts a separate instantiation of the activity that may run in parallel with other instantiations. But don't take my word on this; I admit that I may well be wrong. 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 *************************************************************************
