A Formal Orchestration Model for Dynamically Adaptable Services with COWS

Abstract—The growing complexity of software systems, as well as, changing conditions in their operating environment demand systems that are more flexible, adaptable and depend-able. In many domains, adaptations may occur dynamically and in real time. In addition, services from heterogeneous, possibly unknown sources may be used. This motivates a need to ensure the correct behaviour of the adapted systems, and its continuing compliance to time bounds and other Quality of Service properties. The complexity of Dynamic Adaptation is significant, but currently not well understood or formally specified. This paper elaborates a well-founded model of dynamic adaptation, introducing formalisms written using the process algebra COWS. The model provides the foundation for exploring dynamic adaptation and assessing it against predefined specifications. We consider it a contribution for the design of new models and methodologies for system adaptability