Timed patterns: TCOZ to timed automata

Abstract. The integrated logic-based modeling language, Timed Communicating Object Z (TCOZ), is well suited for presenting complete and coherent requirement models for complex real-time systems. However, the challenge is how to verify the TCOZ models with tool support, especially for analyzing timing properties. Specialized graph-based modeling technique, Timed Automata (TA), has powerful mechanisms for designing real-time models using multiple clocks and has well developed automatic tool support. One weakness of TA is the lack of high level composable graphical patterns to support systematic designs for complex systems. The investigation of possible links between TCOZ and TA may benefit both techniques. For TCOZ, TA’s tool support can be reused to check timing properties. For TA, a set of composable graphical patterns can be defined based on the semantics of the TCOZ constructs, so that those patterns can be re-used in a generic way. This paper firstly defines the composable TA graphical patterns, and then presents sound transformation rules and a tool for projecting TCOZ specifications into TA. A case study of a railroad crossing system is demonstrated

Applying Practical Formal Methods to the Specification and Analysis of Security Properties

The SCR (Software Cost Reduction) toolset contains tools for specifying, debugging, and verifying system and software requirements. The utility of the SCR tools in detecting specification errors, many involving safety properties, has been demonstrated recently in projects involving practical systems, such as the International Space Station, a flight guidance system, and a U.S. weapons system. This paper briefly describes our experience in applying the tools in the development of two secure systems: a communications device and a biometrics standard for user authentication