Databases Reference
In-Depth Information
class hierarchy of distinct instances. All of this also applies to how the soft-
ware component is modeled.
An interesting aspect of the software component is that multiple drivers
are needed to support a single code-operating system combination. That
leads us to understand that this is possibly a good collection-type candidate.
A good analytical understanding of this design challenge is taking place. We
have identified several opportunities for using object-relational techniques
where conventional approaches (pure relational) would have been unman-
ageable. The one challenge that has not yet been addressed is how one goes
about visualizing or modeling the object-relational model, an important fact
that has not gone unnoticed in the DB design community.
6.10
Summary
The first step in developing the object-relational DB system is understanding
the inherent strengths and weaknesses of its predecessors and combining the
most noteworthy elements into one system. The object-relational paradigm
faces a number of challenges because it must meld together characteristics of
two diametrically opposed architectures.
The first object-relational DBs met most, if not all, relational criteria
while addressing only 3050% of the object-oriented spectrum. User-
defined data typing, collection types, rudimentary support for behavior, and
some encapsulation were addressed. The most anxiously awaited features,
namely full support for inheritance, are needed to convince skeptical devel-
opers that object-oriented DBs have come into their own.
Some of the technological factors that will contribute to achieving total
object-relational character are now entering the market. Oracles release of 8i
provides full support for Java. As a matter of fact, Java is on equal ground
with PL/SQL in the DB kernel. The adoption of a true object-oriented lan-
guage is the first step in achieving the last milestone in this new paradigm.
Selected Bibliography
Anyone interested in learning more about object-relational DBs and the
techniques to model them is encouraged to read the following topics:
The Unified Modeling Language User Guide, by G. Booch, J. Rumbaugh, and
I. Jacobson (Reading, MA: Addison-Wesley, 1999).
