The principle of subsidiarity states that central planning only applies to those things that require central planning.
Applying this principle during the planning process means finding an appropriate level of consistency and sharing of policy and services and infrastructure. The concept of subsidiarity refers to the scoping level at which a given set of actions and outcomes are coordinated. Which aspects can be (or must be) determined locally, and which aspects can be determined centrally? Which aspects are managed at department level, or at sector level, or at national level? This calls for architectural thinking about management.
In the early phases of SOA adoption, the primary challenge may be to constrain departmental autonomy over some key issues. However, in the later phases of SOA adoption, SOA-based thinking can be used progressively to decouple enterprise activity. Business transformation may sometimes reduce the need for tight synchronization between different processes, while technology and common standards help reduce the interoperability risks. Such changes may have the effect of empowering a degree of greater local autonomy and differentiation (diversity) against a common platform of shared services. This outcome becomes progressively available as the SOA adoption becomes more mature.