In this brilliant article titled "Classic SOA" Dan North discusses the technlogy agnostic way of designing services. He is spot on in his remark that the venodrs are making SOA look lot more complex than it actually is in order to sell their products and solutions.
"Naturally it is in the vendors’ interest to emphasize the complexity of SOA and then provide a timely and profitable solution. This leads many systems architects into a technology-centric view of SOA, when, in fact, the most important criteria for a service-oriented architect — before tackling the technology — should be a keen understanding of the business.
I am also quite impressed by his explantion on how a single domain model will make little sense for the consumer and the povider of the services and how it becomes diffucult to re-engineer becuase the tight domain model coupling.
He emphasises usage of "busniness concepts", an effectively higher-level, ubiquitous language that ties together all of the finer-grained domain models behind each service.
He goes on to add
"The service contract is then expressed in terms of enterprise-level business concepts, such as a vacation or a dispatch or a sales order, which again decouples the service consumer from the service provider and allows them to evolve independently, while still able to communicate in a common language. The mistake that enterprise information architects (or people with similarly named roles) make is trying to define what the business concept means to each of the people using it"