Author: Nicolai Josuttis
Publisher: O’Reilly, 2007
Pages: 325
ISBN: 978-0596529550
Aimed at: Architects
Rating: 4
Pros: Does a good job of clarifying the SOA landscape
Cons:
Reviewed by: Sue Gee

It can be difficult pinning down exactly what is meant when people talk about SOA and this title tackles this problem head on, devoting its first two chapters to the context and history of SOA including a variety of definitions from other sources and authorities. This serves to demonstrate that it is indeed difficult to settle on an accepted and enduring meaning of either “SOA” or  indeed “service”. Having reviewed other people’s terminology Nicolai Josuttis does arrive at his own definitions and moves on to consider loose coupling and the Enterprise Service Bus, again with the aim of clarifying these concepts. Service classification is the next topic under discussion but, as the reader will have come to expect, Josuttis discusses a range of categorization approaches without prescribing general rules about which to adopt. The next three chapters get onto to the topic of business process management, initially with an overview that introduces some BPM tools and standards, particularly BPEL, Business Process Execution Lange, an XML language for describing business flows and sequences.

One key message of the following chapter that elaborates on the way distributed processing affects the organisation and structure of companies and enterprises is that “SOA is fundamentally a business strategy rather than an IT strategy”. However at this point the book does shift into a more technical gear and the first half of the book concludes with an examination of different ways of modelling a SOA-based architecture and a discussion integrating SOA with frontend and backend processes. The second half is altogether more practical and discusses specific aspects of introducing and running SOA covering topics including message exchange patterns (MEPs),service lifecycle and versioning, security and performance. One chapter is devoted to web services and another to model driven service development and governance is considered as the book draws to a close. However, even when it includes pseudo code, this book can only provide an overview and  doesn’t get down to the technical practicalities of SOA.