A Modeling Methodology for Hierarchical Control Systems and its Application

Current and future computerized systems and infrastructuresare going to be based on the layering of differentsystems, designed at different times, with differenttechnologies and components and difficult to integrate.Control systems and resource management systems are increasinglyemployed in such large and heterogeneous environmentas a parallel infrastructure to allow an efficient,dependable and scalable usage of the system components.System complexity comes out to be a paramountchallenge to solve from a number of different viewpoints,including dependability modeling and evaluation. Keydirections to deal with system complexity are abstractionand hierarchical structuring of the system functionalities.This paper addresses the issue of an efficient dependabilityevaluation by a model-based approach of hierarchicalcontrol and resource management systems. We exploitedthe characteristics of this specific, but important, class ofsystems and derived a modeling methodology that is notonly directed to build models in a compositional way, butit also includes some capabilities to reduce their solutioncomplexity. The modeling methodology and the resolutiontechnique are then applied to a case study consistingof a resource management system developed in the contextof the ongoing European project CAUTION++. The resultsobtained are useful to understand the impact of severalsystem component factors on the dependability of theoverall system instance.