Chapter 5. Services as Building Blocks

The focus of a Service-Oriented Architecture is on the functional infrastructure and its business services, not the technical infrastructure and its technical services. A business-oriented service in an SOA is typically concerned with one major aspect of the business, be it a business entity, a business function, or a business process. This chapter provides an in-depth discussion of the different types of services.

In Section 5.1, we establish a classification that distinguishes between basic, process-centric, intermediary, and public enterprise services, and we discuss the characteristics of these different classes of services and what this means from a design, implementation, and project management point of view. These service types have significantly different characteristics with respect to reusability, maintainability, scalability, and performance; therefore, it's crucial to understand them in order to implement them efficiently.

Section 5.2 introduces SOA layers for design at the application landscape level. As we will demonstrate, SOA layers are largely independent of the system architecture's tiers, which is a major benefit of the SOA approach.