SHF: Small: Evolving Safety Cases in Agile Development Environments

University Of Notre Dame, Notre Dame IN

Investigators

Abstract

Software operating in safety-critical domains must not only support its intended functionality but must also be assuredly safe for use. Delivering such systems requires a rigorous and systematic hazard analysis to identify and mitigate potential hazards. Prior to deployment, a safety case is often constructed that provides claims, evidence, and arguments for system safety. Safety-critical systems have traditionally been engineered using carefully controlled processes which emphasize detailed planning, upfront design, and quality assurance. This has led to the phenomenon referred to as the 'big freeze' in which the cost, effort, and difficulty of introducing new functionality becomes prohibitively expensive. As a result, many organizations operating in safety-critical domains are adopting more agile approaches in which software is delivered on shorter release cycles. At the same time, organizations that have not traditionally worked in the safety domain are increasingly building Cyber-Physical Systems, such as factory-floor robots, unmanned aerial systems and medical devices, often without the knowledge or tools to support appropriate hazard analysis and safety assurance. These two trends -- emerging from opposite ends of the process spectrum -- point to a new way of developing safety-critical software, one which embraces the rigor of safety-critical development while benefiting from the more incremental, faster delivery cycles made possible by agile solutions. The research team will deliver an intelligent solution for creating, evolving, and using trace links within agile safety-critical project environments. The novel Software Artifact Forest Analysis (SAFA) approach will aid validators, verifiers, safety analysts, and other project stakeholders working in an agile environment to understand and analyze the impact of change upon an existing safety case, to assess the safety of the current system, and to evolve the safety case accordingly. The research will deliver a process workflow for guiding developers through the task of creating trace links, traceability solutions for automating the creation and evolution of trace links in an agile project, interactive solutions for visualizing how the system mitigates identified hazards, and techniques for supporting change impact analysis and maintenance of safety-assurance cases. The research directly addresses the emerging industrial challenge of adopting agile processes in safety-critical projects in order to address the `big freeze' problem. The algorithms, tools, and processes delivered through the project are expected to have significant industrial impact. This will be aided by the proactive engagement of industrial partners in test-driving novel and practical solutions produced throughout this project. Opportunities will be provided for broadening participation in computing by engaging underrepresented students at all stages of their academic careers in challenging research projects. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.