The challenge of evolving existing systems to service-oriented architectures

Software systems are an integral part of industrial processes at every level, from low-level production control to enterprise planning. The maintenance challenge presented by such systems is about finding an acceptable balance between risk involved in evolving the system and benefits offered by the update. Service-Oriented Architecture (SOA) promises to leverage software systems to become more efficient and responsive to change through service reuse and process agility. However, for existing systems, this compounds the maintenance problem as SOA represents a "paradigm-shift". It leaves business leaders facing a difficult problem: how to minimise the risk to their investment (existing software systems) and exploit the benefits of migrating a SOA. We describe a pragmatic strategy for addressing the problem and outline the significant challenges that remain.