Book Reviews: Object Databases - The Essentials by Mary E. S. Loomis

Object Databases-The Essentials (Addison-Wesley, 1995, paperback, ISBN 0-~01-563~1-X, 192 pp., $~7.95) introduces and explains the issues required to successfully manage and develop software with object-oriented database management systems (OODBMS). It compares the features of OODBMSs with traditional re-lational database systems (RDBMSs), explains concepts and issues surrounding OODBMSs, and shows methods for using OODBMS on a project. The strength of Loomis' book comes from the emphasis it places on using OODBMS in conjunction with widely-used object-oriented languages such as Smalltalk and C++. Loomis opens by describing traditional software development as a "vaulting process" in which each phase of: takes place in different worlds. The world of requirements analysis and design has its own terms and models based on ER diagrams, dataflow diagrams, and structure charts. When people in the analysis world complete their work they tend to "throw it over the wall" to the programmers , who must translate it into a form that their programming language can accommodate. Finally, the data management people, working behind yet another wall in their world of normalized relational tables and Structured Query Language (SQL), must translate the information they manage into data structures that the programming languages can manipulate. Constantly "vaulting" these walls during development introduces errors and increases maintenance costs. To obviate this problem, Loomis forwards the advantages of having a unified conceptual model in which each phase uses the same methods, terms, and approach. Loomis then argues convincingly that the only methods available today to "tear down the walls" come from object technology. Loomis calls the "no-vault" approach to software development one in which the object model defines all aspects of development. Since objects appear everywhere, they serve to define requirements across application domains just as well as they serve to represent entities in a programming language such as Smalltalk or C++. OODBMSs complete the picture by allowing data managers to use objects to organize information and thereby to operate in the same world as designers and programmers. In Object Databases-The Essentials~ Loomis begins by describing what managers and developers need to meld programming languages and databases together in a development environment. She builds very nicely over a series of chapters to more technical topics deMing with such issues as object sharing and distributed object management. In this sense Loomis' book contains something for everyone who has an interest in or business need for OODBMSs. Following the introductory chapter, Loomis describes the …