A Validation Metrics Framework for safety-critical software-intensive Systems

As software complexity continues to increase in today's systems of systems, conveyance of stakeholder requirements, development to these requirements, and validation of these requirements has become exceedingly more difficult. Safety-critical software-intensive systems of systems require significant verification to ensure that they function as per requirements. Verification is only one portion of ensuring systems function correctly and is typically a well defined activity for software development. Validation is the other portion of ensuring that software is developed to the customer's satisfaction, however is not so well defined. The traditional validation model of matching system specification to stakeholder requirements and expectations does not cater for software safety, where stakeholder requirements and expectations are simply that of a ldquosaferdquo system. We introduce a new model for validation of software safety requirements by proxy. Measurement of software safety is a relatively unexplored aspect of software engineering. Proactive validation of software safety requirements necessitates metrics acting as indicators of requirements validity. This paper presents the Validation Metrics Framework, which is based on a new model for validation of software safety requirements. We demonstrate the application of the framework with a representative safety-critical software-intensive system.