From: Andrew Gabb (agabb@tpgi.com.au)
Date: Sat May 01 2004 - 02:58:18 EST
Overmyer, Scott wrote:
> Ever look at Mac Alford's RDD stuff from the eighties? There
> also was a tool, RDD-100 that used block diagrams to help with
> top-down hierarchical decompositions of problems into components,
> etc., mostly for architecture definition and simulation, but
> also for TDHD for requirements. It was used on a number of
> large-scale system efforts, and with a search I find that the
> tool is still around and now marketed by a company called
> holagent. A look at some of their whitepapers may be interesting
> if you're considering the question of top-down vs. bottom-up
> analysis.
>
> It occurs to me that most tools intentionally support top-down,
> but unintentionally support bottom-up as well, since most
> analysts operate opportunistically.
I think RDD-100 (a systems engineering tool) had a lot going for it wrt its functionality - I remember our software weenies being wowed by a demo of its capabilities in the early 90s (they were using Rose). Unfortunately, at the time it was being serious marketed (by Ascent Logic I believe), there was a standing joke that the '100' stood for $US100k a seat, which didn't help much, because it was too close to the truth.
CORE (also overpriced IMNSHO) was a subset and spinoff from RDD-100, which at one stage promoted itself as an RE tool, but was more correctly an extended ERA tool with a rather klunky graphical interface.
However, I didn't find either of these tools particularly useful in the early front-end RE stages of project, although both may have had some useful capability in the representation of the analysis, and from that point onwards. Having said that, I know others who swore by these and other tools - I guess it depends to some extent on how much you can model in your head.
Keith.Collyer@telelogic.com wrote:
> This reminds me of David Parnas and Paul Clements's classic paper
> "A Rational Design Process: How and Why to Fake It". Although I
> suspect this wasn't the intent. Even if the information is
> gathered bottom-up, it is better presented top-down as that is
> the easiest way for us to navigate around.
I'd forgotten this one, Keith, but you're spot on - that's exactly what I was getting at. I also remember this paper as being a bit more cynical than my views, giving some other reasons as well.
I haven't actually said anything new here (as is common), but it's amazing how often people forget. We don't live in a pure world, particularly in RE, but almost all the models assume a form of purity, or a level of logical representation, which is always a distortion of the actualities of the situations we find ourselves in. It's worth repeating the old army adage: when the map differs from the terrain, believe the terrain.
Andrew
-- Andrew Gabb email: agabb@tpgi.com.au Adelaide, South Australia phone: +61 8 8342-1021, fax: +61 8 8269-3280 ----- ------------------------------------------------------------------------------- To send a message to this mailing list send it to re-online@it.uts.edu.au. To unsubscribe from this mailing list, email majordomo@it.uts.edu.au with the message `unsubscribe re-online' in the BODY of the mail.
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