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From: dav@island.uu.net (David McClure)
Newsgroups: comp.databases,comp.software-eng
Subject: Re: Object-oriented Databases and CASE
Summary: What the world needs now is love sweet love (and a decent CASE/DBMS)
Keywords: CASE, extensible databases
Message-ID: <1450@island.uu.net>
Date: 15 Mar 90 19:21:58 GMT
References: <604@qusunc.queensu.CA>
Reply-To: dav@island.uu.net (David McClure)
Followup-To: comp.databases
Organization: Island Graphics, Marin County, California
Lines: 67

In article <604@qusunc.queensu.CA> faustino@qucis.queensu.CA (Angelique Faustino) writes:
>	
>	I am doing a study on database support for CASE.  Mainly, I
>want to look at object-oriented databases and extensible databases
>and how they improve data repository support for CASE environments.
>
>	Has anyone seen any literature regarding this topic?  Does
>anyone have any opinions?  Suggestions on what DBMS features would
>be convenient for someone using or building a CASE (Computer-Aided
>Software Engineering) environment?
 
Literature/opinions/suggestions: 

A more advanced information model dealing with abstract datatypes should be 
integrated with the standard requirements model (Yourdon/DeMarco, Gane/Sorenson) 
implemented by many of the major CASE vendors, as well as tools made available
in commercial DBMS to implement same.  Ideally, the industrious entrepeneur
would develop a *truly* integrated CASE/DBMS environment instead of trying to
fit one to work with the other...  

Currently, most information models use Chen entity-relationship (ER) notation,
which I find limiting.  I have seen a few fascinating articles in Communications 
of the ACM discussing the extended entity-relationship (EER) model, and I'm 
trying to get more information on this topic myself.  The major points in the
EER model I find interesting deal with "subtype/supertype" or "categories"
and N-ary relationships.  I believe this is along the lines of what you mean 
by "object-oriented" DBMSs; however the term "object-oriented" is whipped
around lately more often than "relational", so you might clarify what you mean 
by its use in this context.  

Anyway, as far as EER models go, I know of no standard as yet emerging in 
commercial CASE products, although some vendors have announced plans for some
type of EER-type information model implementation in the future.  The key 
problem though is that even if some EER model is available in CASE tools, the 
DBMS tools available are also very primitive in this area, and implementing an
EER model would not be an easy task.

Unless some standards do begin to emerge in both areas, I doubt whether an open 
solution -- CASE product X and DBMS product Y -- will ever work effectively.  
Most likely an integrated product must emerge, or else the developer will have 
to settle for some independent modification (read KLUDGE) in order to achieve 
his/her desires.  I'm currently experiencing this myself using IDE's Software
through Pictures (CASE) and Sybase (DBMS).  

Sybase has adhered to a more faithful interpretation of the relational model 
than other DBMS vendors -- "Referential integrity?  Next release, fer shur!" -- 
making extensions less of a pain than might otherwise be necessary.  However, 
allowing simultaneous multi-table updates to multi-table views would go a 
long way towards solving the subtypes/supertypes problem, assuming you use
separate tables for each supertype and subtype.  Mutual exclusivity rules
should also be dealt with somehow -- if this sounds like a mouthful, email me 
and I'll explain my own solution in more depth.

IDE (and probably most other CASE vendors, to be fair) still has work to do, 
although I've been assured by one of their representatives that a revised 
entity-relationship editor is in the works -- whether this will really be an 
EER model remains to be seen.

So there you have it!  I'm sure with just a few weeks of work, some startup
will put all these ideas together and dominate the market by fall.  BTW, I
have a bridge in the New York metro area I'm interested in selling...

-- 
David McClure
> My opinions are not necessarily those of        ||  serenity=>acceptance
> my employer, or anyone else in this damnfool    ||  courage=>change
> world of ours; *think* for yourself.  Rock on.  ||  wisdom=>differentiate