Architectural dependency analysis to understand rework costs for safety-critical systems

To minimize testing and technology upgrade costs for safetycritical systems, a thorough understanding and analysis of architectural dependencies is essential. Unmanaged dependencies create cost overruns and degraded qualities in systems. Architecture dependency analysis in practice, however, is typically performed in retrospect using code structures, the runtime image of a system, or both. Retrospective analysis can miss important dependencies that surface earlier in the life cycle. Development artifacts such as the software architecture description and the software requirements specification can augment the analysis process; however, the quality, consistency, and content of these artifacts vary widely. In this paper, we apply a commonly used dependency analysis metric, stability, and a visualization technique, the dependency structure matrix, to an architecture common to safety-critical systems that was reengineered to reduce safety testing and upgrade cost. We describe the gaps observed when running the analysis and discuss the need for early life-cycle dependency analysis for managing rework costs in industrial software development environments.