ExplicitCase: Tool-Support for Creating and Maintaining Assurance Arguments Integrated with System Models

Assurance cases are collections of standard-mandated documents that entail the specification of system's objectives and a collection of processes, development or verification evidence regarding the satisfaction of the respective objectives. A considerable amount of work has been done in the direction of modelling assurance cases, to support communication and reasoning regarding the system's safety. In this work, we present a set of features of ExplicitCase - a tool for modeling assurance cases. While there is a plethora of tools for creating and managing model-based assurance cases, the uniqueness of our tool is that it integrates assurance case models with system models created in AutoFOCUS3 (AF3) - an open-source model-based development tool for embedded software systems. While trying to keep up with state-of-the-art assurance case editors, the newly implemented features support assurance case creation using typed patterns, change impact analysis for assurance cases, assessment of the confidence in the created assurance arguments, export of the argumentation diagrams generated in ExplicitCase and integration of assurance case models with system models created in AutoFOCUS3. In particular, based on the integration with AF3 system models, we propose automatic support for detecting the impact of a change within system models on the assurance case model, thus enabling the integrated development of system and assurance case models.