A Design and Implementation of an Assurance Case Language

Assurance cases are documented bodies of evidence that provide valid and convincing arguments that a system is adequately dependable in a given application and environment. Assurance cases are widely required by regulation for safety-critical systems in the EU. There have been several graphical notation systems proposed for assurance cases. GSN (Goal Structuring Notation) and CAE (Claim, Argument, Evidence) are such two notation systems, and a standardization effort for these notation systems have been attempted in OMG (Object Management Group). However, these notation systems have not been defined in a formal way. This paper presents a formal definition of an assurance case language based on GSN and its pattern and module extensions. We take the framework of functional programming language as the basis of our study. The implementation has been done on an Eclipse based GSN editor. We report case studies on previous work done with GSN and show the applicability of the assurance case language.