209. SOA offers a mechanism for achieving the agility required for NNEC. Whereas the current stove-piped way of doing business is rigid and difficult to adapt because business functions and the supporting IT are so tightly coupled, an SOA exploits newly available software components and web standards that can be reconfigured easily and quickly. SOA translates capabilities, processes and functions into services which can be invoked by a user through an interface. This requires the services to be available and the user to know the "what, how, how much and when" of accessing them. How the services work is of no consequence to the user but is important to designers and architects. The underlying principles are not new, but the web services and related technology to bring it to life are; reinforced by their wide acceptance.

210. The predominant precept is that SOA is business driven. This puts designated defence Process Owners in the driving seat because they place requirements for service provision. If SOA is to be successful it means that they must truly understand what drives the capability they are entrusted to deliver so that they are in a position to inform/drive how it can be delivered to users in the most effective and efficient manner possible. New technology enables much looser coupling between business processes and the IT systems which support them and so overcome one of the key drivers of cost in most IT deployments - tight coupling i.e. changes in one area requiring a cascade of other required changes in order to work; with familiar cost, time and performance penalties. To support this, a high level governance structure is essential to enforce data and quality of service standards which enable reuse of services.

211. There are many benefits to SOA. They include access to previously unavailable information, the design of reusable services, the ability to make up new services from existing ones, the ability for businesses to make changes without costly IT expenditure, and so on. Moreover, the issues subtending from the use of legacy systems and the requirement to leverage as much value for money as possible from their continued use, becomes much less difficult by adopting a service perspective. For those who embrace SOA and see it through, the prospect of a working NNEC becomes realisable for the first time.

212. SOA is already here and any new major system provided by any one of the leading industry vendors is likely to have an SOA capability embedded in it. However, it should be noted that the federated model of SOA described in this design rule is still an emerging concept which will take time to reach maturity.