Programming WCF Services, 2nd Edition

Services

A service is a unit of functionality exposed to the world. In that respect, it is the next evolutionary step in the long journey from functions to objects to components to services. Service-orientation (SO) is an abstract set of principles and best practices for building service-oriented applications. If you are unfamiliar with the principles of service-orientation, Appendix A provides a concise overview and outlines the motivation for using this methodology. The rest of this book assumes you are familiar with these principles. A service-oriented application aggregates services into a single logical application, similar to the way a component-oriented application aggregates components or an object-oriented application aggregates objects, as shown in Figure 1-1.

Figure 1-1. A service-oriented application

The services can be local or remote, can be developed by multiple parties using any technologies, can be versioned independently, and can even execute on different timelines. Inside a service, you will find concepts such as languages, technologies, platforms, versions, and frameworks, yet between services, only prescribed communication patterns are allowed.

The client of a service is merely the party consuming its functionality. The client can be literally anything—for instance, a Windows Forms class, an ASP.NET page, or another service.

Clients and services interact by sending ...