A QoS-based framework for the adaptation of service-based systems

Since a system may require dynamic adaptation for several reasons (e.g., a new version may be available and a new functionality or a different level of quality of service) it should be possible to dynamically adapt a service-based system in an automated manner. In this paper we give a general overview of the main components of a framework, based on an optimization model, that dynamically adapts a service based system (i.e., both the structural and behavioral software and hardware architecture) while minimizing the adaptation costs and guaranteeing a required level of the system qualities. Adaptation actions can be triggered both by a user request and/or automatically after the runtime violation of system quality constraints, or the appearing/disappearing of services into the environment. In this paper we provide also a deeper discussion of the optimization model that is the core of the framework by providing an example of instantiation of the model together with a first experimentation.