Is a SOA Implementation a Complex System?
Many of the characteristics of such systems of systems line up quite neatly with how ZapThink sees SOA. The core SOA principle of loose coupling in particular leads to the system of systems requirement of autonomous systems. In fact, complex systems theory recognizes that a result of tightly coupling systems is the fact that accidental failures of individual subsystems lead to cascading failures across the entire system. Furthermore, systems of systems depend upon interoperation among systems, rather than integration, where integration of subsystems leads to a unified system, while interoperation among systems is the combination of autonomous systems into a system of systems. Interoperation in systems of systems demands what Fisher calls a node-centric perspective, where each constituent (a Service provider or consumer, say) views the system from its own individual perspective. For each node, a node-centric perspective describes the interactions with its immediate neighbors based upon
