Enterprise SOA

What are service providers?

Frequently when we think of services, we imagine freestanding entities that just exist somehow. However, services are computer programs, and like all computer programs, they must be loaded onto a computer and executed to work. The simplest definition of a service provider is any computer program that offers its functionality to other computer programs as a service. For this book, when we say service, we usually mean web service, so service providers are programs that offer web services. As a practical matter, though, what kinds of programs are service providers?

The most common kind of service providers are existing enterprise applications that are making their functionality available as services. Most of the first wave of services will be created in this manner. This means that enterprise applications such as ERP and so forth will operate in their traditional manner and will provide their functionality as they always have. They also will provide services that will be used by service consumers, mostly composite applications. Eventually, extensions to ERP may be made as composite applications, and then perhaps someday all of ERP may be architected as a service provider with composite applications on top.