Re: domain questionnaire

> >1) I would hesitate to call ORM "a dialect of entity-relationship
 models".
> >ER modeling models entities, attributes, and relationships between
 entities.
> >ORM models obects and the roles they play with other objects.
>
> Role == Relationship?

Sometimes, but not quite. Most (read: in typical data modeling applications) roles to other objects tend to map to attributes/columns. Some roles between object types map as relationships. It has to do with the total collection of roles each object type has, the uniqueness constraints on those roles, and the mandatory constraints on those roles.

> >There are no
> >attributes, and the elementary fact concepts ensure normalization.
>
> Heh-heh. Good trick, without attributes. Or even with them. We all
> know normalization is trivial, right?

he he he

It is a good trick. Essentially, ORM's use of elementary facts maps out the FD's, and thus algorithms can be applied to make it "optimally normalized".

> >2) The conference in Anaheim is not an ORM conference, it is the
 Meta-data
> >Conference and DAMA International Symposium. More techniques than ORM
 will
> >be represented there, some good and some terrible, I'm sure. It is true
 that
> >there will be two presentaions covering ORM there, one by myself and one
 by
> >Dr. Terry Halpin.
>
> Well, I might just wander by. I'm a big fan of meta-data (OK I'm
> easily amused). Waitaminute, $1k to wander by? I might be busy that
> week after all.

It is pricey, but I went last year and it was quite informative. Then again, I personally didn't pay my fee, so.... <s>

HTH,
Scot.

Partner, InConcept, Inc.

     http://www.inconcept.com

Editor, The Journal of Conceptual Modeling

     http://www.inconcept.com/JCM Received on Sat Feb 24 2001 - 17:12:12 CET