We initially described SOA without mentioning Web s ervices, and vice versA.This is because they are ortho gonal: service-orientation is an architectural (71) whil e Web services are an implementation (72).The two c an be used together, and they frequently are, but the y are not mutually dependent.
For example, although it is widely considered to be a distributed-computing solution,SOA can be applied to advantage in a single system,where services might b e individual processes with well-defined (73) that co mmunicate using local channels,or in a self-contained cluster, where they might communicate across a high -speed interconnect.
Similarly, while Web services are(74) as the basis for a service-oriented environment, there is nothing in th eir definition that requires them to embody the SOA p rinciples. While(75)is often held up as a key characte ristic of Web services,there is no technical reason that they should be stateless-that would be a design choi ce of the developerwhich may be dictated by the arc hitectural style of the environment in which the servic e is intended to participate.
