By Ellen Wixted
|"There's so much bad database design in the world," Dr. Terry Halpin says in his soft Australian drawl. "The problem is that the people who understand what the database needs to do are businesspeople, and the people who actually build the system are techies. There's often a communication breakdown, and what results are systems that don't work as well as they could."|
As far as Halpin is concerned, the high-level conceptual modeling supported by Object Role Modeling (ORM) is the answer to communication breakdowns. "ORM makes it possible for businesspeople and database designers to literally speak the same language, so validating a database design is much more straightforward. With ORM, formal logic is accessible to businesspeople, and they're protected by the strength of it." Visio 2000 Enterprise Edition introduces support for ORM in the context of a powerful suite of IT design tools. With Enterprise Edition, implementing conceptual models created in ORM as relational or object-relational database schemas is straightforward.
In the early '80s, Halpin was introduced to the Natural language Information Analysis Method (NIAM), an early ORM variation, at the University of Queensland in Australia. "It all made sense," he says, remembering that moment of illumination. Within a year, he was teaching university courses in conceptual modeling and had switched the topic of his Ph.D. thesis from proving theorems automatically to formalizing the ORM method. As part of his thesis, Halpin worked on proving schema equivalence. "Two people might model the same domain in different ways," he explains. "How do you know that they're describing the same thing? I was interested in developing an approach that could formally prove whether two different models were equivalent." In 1989, Halpin and co-author Dr. Shir Nijssen, another leading ORM expert, published the groundbreaking book Conceptual Schema and Relational Database Design.
In 1995, Halpin left his teaching post at the University of Queensland to work full-time in the commercial software industry, where his focus has been on developing database design tools. He's found the change invigorating. "I'm still involved in a number of academic committees, so I stay up-to-date on state-of-the-art research. And while I miss teaching, I don't miss marking exam papers and assignments. I reached a point in my academic career where I didn't want to invest energy in research unless it had obvious practical value. It's motivating to work in an industry where you can see the immediate use of your research."
The Visio era
At Visio Corp. these days, Halpin is researching ways that ORM can be used to create conceptual models of complex object-oriented software design projects. "As the Unified Modeling Language, or UML, gains popularity, the higher-level conceptual-analysis approach of ORM can help software designers capture and validate the business rules relevant to their application in much the same way it's helpful to database designers."
The geographic change has been a welcome one, too. "I really love the environment here in Seattle," Halpin says. "It's gorgeous. And the people are even more polite than they are in Oz. Sometimes I miss the beaches at homeit's much too cold to go body-surfing herebut I also love trekking in the mountain forests." In addition to his academic credentials, Halpin holds a black belt in judo and a blue belt in karate. Like many other Seattleites, he cultivates an interest in gardening and reads widely, tackling everything from science fiction to philosophy texts. And with grown children still living in Australia, he and his wife, Norma, travel Down Under regularly.
You can find more information about ORM at
the official site for conceptual
data modeling. For an in-depth look at ORM and
conceptual database design, you can order the second edition
of Dr. Halpin's Conceptual Schema and
Relational Database Design by emailing WytLytPub@att.net. A
third edition of the book will be published in 2001 under the new title Information Modeling and Relational Databases by Morgan Kaufmann Publishers
(www.mkp.com). For details about Visio Enterprise
Edition, visit www.microsoft.com.