In component-based safety-critical real-time systems it is crucial to determine which component(s) caused the violation of a required system-level safety property, be it to issue a precise alert, or to determine liability of component providers. In this paper we present an approach for blaming in real-time systems whose component specifications are given as timed automata. The analysis is based on a single execution trace violating a safety property P. We formalize blaming using counterfactual reasoning ("what would have been the outcome if component C had behaved correctly?") to distinguish component failures that actually contributed to the outcome from failures that had no impact on the violation of P. We then show how to effectively implement blaming by reducing it to a model-checking problem for timed automata, and demonstrate the feasibility of our approach on the models of a pacemaker and of a chemical reactor.

The complex interactions appearing in service-oriented computing make coordination a key concern in service-oriented systems. In this paper, we present a fault-based method to generate test cases for component connectors from specifications. For connectors, faults are caused by possible errors during the development process, such as wrongly used channels, missing or redundant subcircuits, or circuits with wrongly constructed topology. We give test cases and connectors a unifying formal semantics by using the notion of design, and generate test cases by solving constraints obtained from the specification and faulty connectors. A prototype symbolic test case generator serves to demonstrate the automatizing of the approach.