Conceptualizing Service-Based Information System Evolution as a Complex Adaptive System

Service-based information systems are considered a cornerstone in architecting modern enterprise applications. Service-oriented architecture (SOA) is designed to enable dynamic integration of heterogeneous application elements, and thus improve enterprise agility. This is achieved by publishing reusable services on a common registry or enterprise service bus to become available to users who will request and invoke them according to their business needs. In this paper it is argued that service-based information systems are different from componentbased systems. SOA relies on the concept of contracting services to become invoked by users through service matching and binding, beside a middleware interface that integrates heterogeneous components (as supported by component-based architecture principles). In order to enable service evolution it is suggested to conceptualize service-based information systems as a complex adaptive system. Complexity science seeks to theorize the phenomenon of emergence of new properties and the spontaneous creation of new order, and thus provides elements to realize adaptability and evolution. By mapping complexity principles to SOA features factors that would facilitate information service evolution can be derived. It is concluded that in order to enable sustainable evolution of information services controlling factors, such as contracting, licensing, provenance, reliability and sustainability are paramount beside component-based development principles that include reusability, loose coupling, inter-operability, scalability and platform-independence. New programming discipline practices are also concluded, that include service choreography model, BPEL specifications, meta-data specifications, SLA specifications, service semantics and service tests. These ensure fast development balanced with discipline and quality, beside extensive collaboration and interactions facilitated by conventional agile development practices like JAD sessions and prototyping.