Process Analysis Toolkit  (PAT) 3.5 Help  
3.2 Real-Time System (RTS) Module

Specification and verification of real-time systems are important research topics which have practical implications. During the last decade, a popular approach for specifying real-time systems is based on the notation of Timed Automata. Timed Automata is powerful in designing real-time models with explicit clock variables. Real-time constraints are captured by explicitly setting/reseting clock variables. A number of mechanized verification tools support for Timed Automata have proven to be successful (e.g., Uppaal, KRONOS, TEMPO, RED and Timed COSPAN).

Models based on Timed Automata often adapt a simple structure, e.g., a network of Timed Automata with no hierarchy. The benefit is that efficient model checking is made feasible. Nonetheless, designing and verifying real-time systems are becoming an increasingly difficult task due to the widespread applications and increasing complexity of such systems. High-level requirements for real-time systems are often stated in terms like deadline, timeout, and waituntil. In industrial case studies of real-time system verification, system requirements are often structured into phases, which are then composed sequentially. Unlike Statechart (with clocks) or timed process algebras, Timed Automata lacks of high-level compositional patterns (besides parallel composition of a network of Timed Automata) for hierarchical design. As a result, users often need to manually cast those terms into a set of clock variables with carefully calculated clock constraints. The process is tedious and error-prone.

This module supports real-time systems which are specified compositional timed processes. Timed processes running in parallel may communicate through either a shared memory or channel communications. Instead of explicitly manipulating clock variables, a number of timed behavioral patterns are used to capture quantitative timing requirements, e.g., delay, timeout, deadline, waituntil, timed interrupt, etc. For such systems, a model checking algorithm can be used to explore on-the-fly all system behaviors by dynamically creating (only if necessary) and pruning clock variables (as early as possible), and maintaining/solving a constraint on the active clocks.


 
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