A value-based approach to flexible decision making in real time dependable systems

This paper deals with real-time dependable systems required to achieve the best usage of their resources even under adverse circumstances as transient overloads or component failures. Various possible trade offs among the different application requirements must be considered to allow a flexible management of System resources. On the basis of a simple formulation of the concept of value in real-time systems we propose a performability metric that represents a suitable measure of System accomplishment level. A planner component is defined which is responsible far implementing a value-driven admission policy that maximises the performability index and hence achieves the optimal utilisation of available System resources. The numerical evaluation of a System organisation taken as an example is performed for different load sets as well as a sensitivity analysis versus the most rilevant model parameters.