Service-Oriented Architecture (SOA) techniques are applicable to the system layer (domain) of enterprise architecture as a system development methodology.* SOA is an approach to building IT systems out of common software modules (parts), called services. The goal of SOA-based development is to enable organizations to assemble business systems out of simpler cataloged modules. SOA methods are now being explored by enterprises with the goal of achieving flexibility, agility, and productivity enhancements in IT development. Indeed, in allowing reuse, SOA lowers long-term integration costs and provides faster delivery of business applications. This approach to development may typically require more upfront effort in design and planning when the paradigm is first adopted and applied, but, in theory, it enables organizations to increasingly build systems more rapidly and cheaply as the inventory of reusable modules grows over time.