It seems to me that the real question is "what is the diagram trying to
visualize?' -- and when you use an AD (with or without Swim Lanes -- I very much
prefer the former) to visualize the flow and interaction between Actors and the
System in a Use Case, you are looking at the system "from the outside," which is
what the UC view is supposed to do....the fact that you've used an AD is
immaterial...the fact that you've viewed the system from outside is the critical
fact....
On a related subject: I do think that Rational and RUP have blurred/confused
things a bit by combining the Unified Process's view that there are two distinct
workflows -- Analysis and Design -- into one single workflow (Analysis and
Design).....I have found considerable value in formalizing the Analysis workflow
via UC realizations that are implementation independent and look basically like
Jacobson's Robustness Analsysis stereotypes (and RUP's Analysis classes) placed
in Collaboration (or responsibility-based Sequence) diagrams....the advantage of
going through a round of UC realization a the "concept-not-class" and
"responsibility-not-operation/message" level is that it
a) helps you discover things about the UC you may have overlooked; and
b) firmly established a tracability link into the UC realizations at the design
level.
Also, I have found that the ability to produce implementation-independent UC
realizations (vs implementation-specific design-level ones) may not lie with the
same person....System Analysts are, in general, much more willing to be (at
least for the moment) blissfully ignorant of implementation details while simply
modeling responsibility-based collaborations between instances of analysis model
concepts rather than design-level classes .....designers, on the other hand,
tend to want to get immediately to the class and message level in the
realization....the Unified Process argues, I think, very convincinly for having
a UC Realization--Analysis activity which is separate from the UC
Realization--Design activity.....I wonder if Rational combined the two UP
Workflows in large part because of their essentially identical tooling
requirements....but I don't know that.....
In the RUP class I took, the instructor said that Rational believes that
developers/designers can gather requirements, build Analysis models as needed,
and move to design and that therefore the workflow Analysis and Design should be
considered as a single workflow....maybe that's true....but I've found it hard
to keep good designers at an implementation-independent level for too long. --
and also found that their work is made much easier and traceable (i.e. their
implementation-specific compromises much easier to evaluate and potentially
negotiate with customer requimenets) in the presence of formal UC Realizations
at the Analysis level....
charlie
************************************************************************
* Rose Forum is a public venue for ideas and discussions.
* For technical support, visit http://www.rational.com/support
*
* Admin.Subscription Requests: [EMAIL PROTECTED]
* Archive of messages:
http://www.rational.com/products/rose/usergroups/rose_forum.jtmpl
* Other Requests: [EMAIL PROTECTED]
*
* To unsubscribe from the list, please send email
*
* To: [EMAIL PROTECTED]
* Subject:<BLANK>
* Body: unsubscribe rose_forum
*
*************************************************************************
