Black Belt Design:
Asymetrix Corp.’s Dr. Terry Halpin
By Maurice Frank
This interview appeared in the September 1995 issue of DBMS and is reproduced here by permission.
Using object role modeling to design relational databases.
For many developers, entity relationship (ER) modeling and relational database design go
hand in hand. But a growing number of designers have found database design nirvana
using another methodology known as object role modeling (ORM). ORM uses English
sentences to express how objects relate to one another, and what constraints and business
rules apply to these relationships. While based on techniques dating back to the early
1970s, ORM recently gained popularity with the February 1994 release of InfoModeler, by
Asymetrix Corp. (Bellevue, Wash.).
Because ORM expresses design details using English sentences, many developers
have found it an effective way to present a database design to non-technical end users
who can easily understand it, and correct it where necessary. This ability to verbalize a
model is a unique and compelling advantage of ORM.
Dr. Terry Halpin is the man behind the model at Asymetrix. As the head of research
at the company, Dr. Halpin guides the implementation of ORM in InfoModeler and other
related products Asymetrix is developing. Halpin began working with ServerWare before
Asymetrix acquired that firm. He is also a senior lecturer in Computer Science at the
University of Queensland, Australia, and the author of Conceptual Schema and Relational
Database Design, 2nd Edition, (Prentice Hall, 1995). Terry has a black belt in Judo and a
blue belt in Karate.
DBMS Technical Editor Maurice Frank discussed ORM with Dr. Halpin at the IFIP
Data Semantics Conference in Stone Mountain, Georgia, in May. An edited transcript of
their conversation follows.
DBMS: What is object role modeling?
HALPIN: ORM is a conceptual modeling method for designing information systems. It
views the application world in terms of objects that play roles. These roles may be played
in isolation (for exam