A Dual Language Approach to Software Formal Specifications and Safety Analysis

Abstract

In this paper we present a systematic approach to apply Statecharts modeling and analysis to safety-critical systems. Procedures are devised to first convert Startchart specifications to fault trees for hazard analysis, and then analyze the constructed fault trees to generate accident sequences and express them in UML sequence diagrams. Thus, incorrect or hazardous states and scenarios can be identified so as to assist the designer to modify the system. Our systematic approach makes the conventional subjective fault tree construction objective and repeatable. Thus, safety analysis using formal specifications can be done automatically. Furthermore, we convert the statechart specifications into temporal logic for safety or correctness proof. With the dual specification languages, our method takes the advantages of statecharts’ visual understandability and temporal logic’s proof clarity. A railroad-crossing case is given to demonstrate the feasibility and effectiveness of our method.