Re: Another view on analysis and ER
Date: Thu, 06 Dec 2007 15:41:00 GMT
Message-ID: <gKU5j.11166$Uy.8680_at_trndny07>
"JOG" <jog_at_cs.nott.ac.uk> wrote in message
news:9870400b-bfd4-452a-9578-b958c0a13909_at_s8g2000prg.googlegroups.com...
> On Dec 6, 10:58 am, "David Cressey" <cresse..._at_verizon.net> wrote:
> > "Jon Heggland" <jon.heggl..._at_ntnu.no> wrote in message
> >
> > news:fj8fff$3ed$1_at_orkan.itea.ntnu.no...
> >
> >
> >
> > > Quoth David Cressey:
> > > > "Jon Heggland" <jon.heggl..._at_ntnu.no> wrote in message
> > > >news:fj6737$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.
>
> May I also add that research journals don't seem to be according to
> the definition of E/R as an analysis tool.
>
> This is from July 2007, Transcations of Information Systems, one of
> the ACM's top rated journals:
>
> "Entity-relationship (ER) modeling is a widely accepted technique for
> conceptual database /design/."
Unfortunate nomenclature. Received on Thu Dec 06 2007 - 16:41:00 CET