Have you ever looked at a child's toy and thought, "I wish they had that when I was growing up?" I had that familiar feeling while reading Web Services: Building Blocks for Distributed Systems by Graham Glass. Having pored over various specifications, articles, and newsgroup archives over the past year, Web Services is the type of book that I wish I had when I first approached the topic. The book will be a help to developers, architects, and technical managers that want to become acquainted with Web services.

The book starts with a short, short history of computing and a brief summary of Web services. The reader is quickly introduced to the basic concepts and technologies of Web services, including SOAP, WSDL, and UDDI. One of the best features of the book is that concepts are explained from several points of view using analogies that will make sense to a wide audience. The book introduces WSDL (Web Services Description Language) saying:

WSDL is the XML equivalent of a resume - it describes what a Web service can do, where it resides and how to invoke it. If you're familiar with CORBA or COM, think of WSDL as the Web services equivalent of Interface Definition Language (IDL) and type libraries.

In the second chapter the reader is led through a quick and dirty introduction to building a web service using GLUE. It's worth noting that although GLUE is a product from the author's own company, the chapter focuses on the underlying technologies and standards and not on GLUE's proprietary implementation. Java developers will most easily digest the examples but those more familiar with other languages and platforms should be able to work through them with minimal problems. Once the reader has been introduced to the overall concept of Web services, the book dives into greater detail.

Chapters 3-6 are devoted to the important topics of WSDL, Data Mapping, Security, and UDDI respectively. Each of these chapters is composed of topic overviews, XML snapshots, detailed discussion, and related demonstrations. These sections are the technical heart of the book and provide the developer with a solid foundation for understanding Web services technologies. If you have been given the weekend to become the company or department expert on Web services, these chapters and the related demonstrations will help you along.

Chapters 7 and 8 discuss the relationship between Web services and Java's J2EE and Microsoft's .NET. The J2EE section shows how one vendor, BEA, implemented Web services on top of their WebLogic application server. Cross-vendor interoperability is also demonstrated when a GLUE client is used to consume an Enterprise Java Bean published as a WebLogic Web service. The .NET chapter focuses on how to build and publish a Web service using Visual Studio.NET and C#. Chapter 9 then combines the previous two chapters by demonstrating cross-language interoperability between .NET and J2EE services. While the example is fairly involved, it's explained step-by-step and is easy to implement.

The final chapter predicts that Web services will evolve into an increasingly larger and more distributed computing platform that will combine web services protocols with peer-to-peer computing. The evolution of P2P is tracked from Napster to Gnutella to Fastrack and the strengths and challenges of each solution are discussed. Finally, the author lays out his vision for how web services and distributed computing could solve major problems in education, telecommunications, and e-commerce.

My only disappointment in the book is its lack of commentary on the near-term future and challenges of Web services. The author has real-world experience implementing a Web services toolkit and working with standards like SOAP, XML Schema, WSDL, and UDDI. This experience would make for an interesting chapter on what's missing from the current Web services picture and the merits of various solutions being proposed to fill the gaps. For example, there are no official Web services standards for general work flow - but a discussion of IBM's Web Services Flow Language and competing solutions would give the user a better understanding of the web services landscape.

The book is a solid introduction to Web services that will help a reader start the process of progressing from novice to expert. Users can also get an excellent feel for how Web services relates to the J2EE and .NET computing platforms. Developers, architects, and managers from all technical backgrounds will find their introduction to Web services goes more smoothly with this book in hand.

Web Services: Building Blocks for Distributed Systems
by Graham Glass
Prentice Hall PTR, 2001
ISBN: 013062569
$39.99