Clark introduces a framework for the .NET platform that provides several basic building blocks for creating enterprise application integration (EAI) solutions, that is, solutions whose sole purpose is to allow systems that were designed separately to interoperate.

The book comprises 18 chapters and three appendices that I have organized into five logical parts. The first part, chapters 1 to 3, introduces EAI in an abstract, easy-to-understand manner. The second part, chapters 4 to 11 and 13, reports on the main components of the framework, namely: a Web service (which acts as a gateway to the system), the logging subsystem, the controller (which takes care of splitting and redirecting the requests that come from the Web service to the appropriate handlers), the request handlers (each of which implements the response to a request), the steps (which implement the individual steps that need to be performed to accomplish a request), the agents (which are communication façades), and the business rules (which allow a request to be intercepted before it is processed to make sure that the appropriate conditions are met). Chapter 13 illustrates how to use the framework from C#, Java, and Perl client applications.

The third part comprises chapters 12 and 14: the former reports on various enhancements and illustrates one of them, whereas the latter reports on the structure of the database used to store information about the components described in the previous part. The fourth part, chapters 15 to 18, gives shallow tutorials on unified modeling language, Extensible Markup Language (XML), simple object access protocol (SOAP) (with an emphasis on SOAP headers and their applications to authentication), and testing techniques. The fifth part comprises three appendices in which the author reports on the .NET classes that interact with the Windows registry, regular expressions, and Structured Query Language Server.

I recommend the first part to people who know little about EAI and wish to get an overall picture in roughly 60 pages. Clark’s style of writing is a little informal, but I think that the anecdotes and pieces of advice he provides are the right way to attract the attention of the reader; I recommend the books by Hohpe and Woolf [1] or Fowler [2] as complementary readings. The rest of the book is for people who are using Clark’s framework or wish to get familiar with it from a programmer’s perspective. Unfortunately, it is not easy to get the overall picture since the book is peppered with long C# listings whose structure or design is not explained sufficiently.

Before concluding, I must also mention that the role of Web services (WS) is not put in a proper context since the current standards under the service-oriented architecture umbrella constitute quite a serious effort to solve EAI problems effectively by means of de facto industrial standards, such as WS-Authorization, WS-Choreography, or WS-Orchestration. No reference to these standards is made and no comparison with other EAI frameworks is presented.