Title:  SOA: Principles of Service Design 
Author: Thomas Erl
Publisher: Prentice Hall, 2007
ISBN: 978-0132344821
Aimed at: Architects, analysts and developers designing services for SOA
Rating: 3
Pros: Well-produced volume, authoritative, comprehensive and practical
Cons: Wordy and expects to be read in conjunction with rest of series
Reviewed by: Sue Gee

This is Thomas Erl’s third volume about SOA in Prentice Hall’s Service-Oriented Computing series of which he is the editor. Through his books, articles, training and consulting services Erl has become the established authority on SOA and other authors tend to quote his ideas. This title sets out to provide “practical, comprehensive and in-depth coverage” of the service-orientation design paradigm, illustrated by a case study that is continued throughout the volume, marked out by the use of grey panels. Colour is also employed to highlight notes, examples, best practices and summaries of key points and is used to good effect in high-quality illustrations.

The bok is divided into four distinct sections. Part I: Fundamentals defines key concepts and terms. Having established the need for a design framework the next section, Part II, presents eight key design principles, each of which is explored in a separate chapter. The chapters on Service Contracts, Coupling, Abstraction, Reusability, Autonomy, State Management and Statelessness, Discoverability, and Composition share the same structure. First the concept under discussion is explained from both an abstract and a historical perspective then each principle is profiled using a table for uniformity. The Principle Profile table has entries for Short Definition, Long Definition, Goals, Design Characteristics, Implementation Requirements and Web Service Region of Influence which includes a diagram to illustrate its role. You might be sceptical that it would be possible to shoehorn eight distinct principles into a common table format but each chapter continues with much more detail including the limitations and risks associated with each principle and an example from the case study. Part III compares principles and concepts, presents guidelines, considers supporting practices and maps service-orientation principles to strategic goals. The final section has appendices including the conclusion to the case study and a set of process descriptions.

<Reviewed in VSJ>