Preface

"Web services are a mess!"

"There are more than 150 Web services (WS-*) specs!"

"Simple? This stuff is more complicated than CORBA!"

"There is no architecture; just a bunch of competing specs!"

"These specs are denser than plutonium!"

Those are some of the statements we've heard from peopleincluding our own colleaguesabout Web services. That's why we wrote this book: to show that the WS-* platform is not a random walk through a space of WS-* specifications but rather an organized, structured architecture with well-defined design and architectural objectives. We apply these objectives when working on WS-* specifications and when deciding whether or not we need a new specification in a certain area.

The objective of this book is to present the cohesive, structured architecture of the Web services platform that we have been helping to define. The architecture is designed to enable loosely coupled interaction between services with business-quality reliability, security, and transactional capabilities. We start by presenting some of the business worlddriving forces that are motivating the creation of the service-oriented computing platform (Chapter 1, "Service-Oriented Architectures"). Then we focus on Web services as a realization of this service-oriented computing platform and indicate which specifications contribute to the platform (Chapter 3, "Web Services"). After that, we consider each major part of the platform and offer the insight that went into defining the specifications that govern that component. We cover the messaging framework, describing metadata, reliable interaction, security, and service composition in different parts of the book. Before concluding, we consider two case studies to illustrate how the Web services platform can address both intranet and extranet integration scenarios. In the concluding part, we summarize the platform and give our perspectives on why the integrated architecture we present makes sense and will "win" the standards battle. Finally, we present our thoughts on the future of the Web services platform.

At the end of this book, you should no longer feel that Web services has no architecture or that the architecture is hidden somewhere between 150+ WS-* specifications. You might not agree with our choice of components that comprise the architecture, but we chose the set based on the fact that those were designed from the ground up to work together to solve a single problem: that of being a ubiquitous platform for integrating heterogeneous systems to enable rich business communication.