Runtime enforcement of timed properties usinggames

Abstract

Abstract This paper deals with runtime enforcement of timed properties with uncontrollable events. Runtime enforcement consists in defining and using an enforcement mechanism that modifies the executions of a running system to ensure their correctness with respect to the desired property. Uncontrollable events cannot be modified by the enforcement mechanisms and thus have to be released immediately. We present a complete theoretical framework for synthesising such mechanism, modelling the runtime enforcement problem as a Büchi game. It permits to pre-compute the decisions of the enforcement mechanism, thus avoiding to explore the whole execution tree at runtime. The obtained enforcement mechanism is sound, compliant and optimal, meaning that it should output as soon as possible correct executions that are as close as possible to the input execution. This framework takes as input any timed regular property modelled by a timed automaton. We present GREP, a tool implementing this approach. We provide algorithms and implementation details of the different modules of GREP, and evaluate its performance. The results are compared with another state of the art runtime enforcement tool.