A service-oriented analogy

Let's take your average cosmopolitan city. It is already full of service-oriented businesses. Individual companies are service-oriented in that each provides a distinct service that can be used by multiple consumers. Collectively, these businesses comprise a business community. It makes sense for a business community not to be served by a single business outlet providing all services. By decomposing the community into specialized, individual outlets, we achieve an environment in which these outlets can be distributed.

When coupled with "architecture," service-orientation takes on a technical connotation. "Service-oriented architecture" is a term that represents a model in which automation logic is decomposed into smaller, distinct units of logic. Collectively, these units comprise a larger piece of business automation logic. Individually, these units can be distributed.

Distributing automation logic into separate units is nothing new. What is it then that makes service-oriented separation so different? Much of this book is dedicated to answering that question. However, let's take a preliminary look at some notable distinctions.

Even in a distributed business community, if we impose overbearing dependencies, we could inhibit the potential of individual businesses. Although we want to allow outlets to interact and leverage each other's services, we want to avoid a model in which outlets form tight connections that result in constrictive inter-dependencies. By empowering businesses to self-govern their individual services, we allow them to evolve and grow relatively independent from each other.

Though we encourage independence within our business outlets, we must still ensure that they agree to adhere to certain baseline conventionsfor example, a common currency for the exchange of goods and services, a building code that requires signage to conform to certain parameters or perhaps a requirement that all employees speak the same language as the native consumers. These conventions standardize key aspects of each business for the benefit of the consumers without significantly imposing on the individual business's ability to exercise self-governance.

Similarly, service-oriented architecture (SOA) encourages individual units of logic to exist autonomously yet not isolated from each other. Units of logic are still required to conform to a set of principles that allow them to evolve independently, while still maintaining a sufficient amount of commonality and standardization. Within SOA, these units of logic are known as services.