When we need to write a new computer program, we do not usually write it from scratch; instead, we usually copy the patterns of another program we have written. If that is not sufficient, we refer to the experts. This book about software patterns is based on the wisdom and collective experience of software programmers, engineers, and architects. It is designed for both novices and experts, as a text for a software engineering course or as a reference guide. The authors use a standardized pattern description template to describe patterns in this book: keywords range from “Name” through “See Also.” “Solution” uses class responsibility-collaborator (CRC) diagrams to define objects, and “Structure” uses object modeling technique (OMT) diagrams to relate objects. “Dynamics” are described using object message sequence charts (OMSCs) to describe the communications protocol between objects, that is, the processes or tasks and subtasks that send and receive messages between the objects.

This book divides patterns into three categories: architectural, design, and idiom. The architectural pattern, a fundamental or high-level organization, is defined by relating subsystems. Design patterns decompose subsystems into other related subsystems, or components. Idioms are low-level patterns specific to a programming language. The architectural patterns discussed in the book are grouped into categories: “From Mud to Structure,” “Distributed,” “Interactive,” and “Adaptable” systems. Design pattern groups discussed are “Structural Decomposition,” “Organization of Work,” “Access Control,” “Management,” and “Communication.” The Internet is described with these patterns: the TCP/IP communication protocol is an example of the architectural Layers pattern; hypertext link processing between clients and brokers is an example of the architectural Broker pattern; and the Netscape browser is an example of the Client-Dispatcher-Server design pattern. The Blackboard architectural pattern is used in artificial intelligence. The architectural pattern Microkernel is the basis for DOS operating systems.

Hopefully, the authors have outlined a pattern for your use or have given a reference to a good prospect. Choose one or more architectural patterns for the high-level part of the design, then select as many design patterns as are applicable to use in subsystems. The “Variants” keyword of the pattern description template may give descriptions or references to other patterns that would be a subset of the pattern described, perhaps using fewer objects, different relationships, or a different communications protocol. In addition to “Variants,” there are references to patterns throughout the book. The reference section points to books, journal papers, and Web sites. The book is completed by sections on pattern classification and comparison to patterns referenced; mention of peer figures in the pattern community; and an index of patterns.

This excellent book on software patterns would be complemented by Plauger’s book on patterns of program design [1].