Chapter 1. Service-Oriented Architectures

This chapter introduces the concept of Services and the associated architectural paradigm, Service-Oriented Architecture (SOA). SOA has emerged as a direct consequence of specific business and technology drivers that have materialized over the past decade. From the business side, major trends such as the outsourcing of noncore operations and the importance of business process reengineering have been key influences driving the surfacing of SOA as an important architectural approach to business information technology (IT) today. From the technology side, the past 15 years have resulted in a realization of the importance of middleware standards and architectures, learning in particular from the successes and failures of distributed object systems and message-oriented middleware.

As an architectural concept, SOA permits multiple approaches for the realization and deployment of an IT system that has been designed and built around its principles. This book focuses on a specific technology that, arguably, has the most significant commercial visibility and traction, and that is Web services. Web services technology is a standards-based, XML-centric realization of an SOA. This chapter examines the motivation behind Web services and some of the main architectural concepts of SOA. Chapter 3, "Web Services," presents an overview of a Web services platform that provides the foundation to accomplish an SOA stack. Chapter 2, "Background," offers some required background so that you can understand the rest of this book.