Re: Another view on analysis and ER

"Jon Heggland" <jon.heggland_at_ntnu.no> wrote in message news:fj8fff$3ed$1_at_orkan.itea.ntnu.no...
> Quoth David Cressey:
> > "Jon Heggland" <jon.heggland_at_ntnu.no> wrote in message
> > news:fj6737$o2p$1_at_orkan.itea.ntnu.no...
> >> Quoth David Cressey:
> > Not all modeling is analysis. Some of it is design. In particular, I'm
> > going to claim that you discover attributes, but you design relvars.
I've
> > already have the second claim confirmed by Bob and others.
>
> Yet when are discovering attributes, you presumably write them down
> somehow. Is it the case that if you do it using E/R notation, you are
> doing analysis, but if you do it using some relation- or predicate-based
> representation, you are doing design?
>
> Or perhaps it's simpler: Analysis is what you're doing when you're
> talking with the subject matter experts; design is what you're doing
> when you're not. :)
>
> > Bob's distaste for pretty pictures should not obscure the mian theme. A
> > model isn't a "pretty picture" as such. Rather, a "pretty picture" is
the
> > projection of a model on a flat screen. Other projections have been
> > proposed. A table written on a whiteboard, with some imaginary sample
data
> > written into it, proposed by another participant, is another
projection of
> > a model on a flat screen.
>
> Ceci n'est pas une pipe... Then is the model wholly intangible, existing
> only in a platonic sense inside the designers (or analyst's) head? Never
> mind, I see your point---but that doesn't answer my question: When is
> modelling design, and when is it analysis? A bald statement that
> relation-based models are designed doesn't cut it, even if it is
> seconded; I need rational arguments.

If you are modeling features of the problem, it's analysis. If you are modeling features of both the problem and the solution, it's design. Received on Thu Dec 06 2007 - 11:58:57 CET