Incremental Experimentation: a methodology for designing and analyzing distributed safety-critical systems

In safety-critical systems requirements for safety and reliability are in conflict with those for real-time responsiveness. Due to unpredictable environmental needs the trade-off between measures to accommodate the conflicting objectives has to adapt to the external situation. Finally there cannot be any closed-form (formal) approach taking care at the same time of the (external) time constraints or deadlines, and the synchronization requirements in the distributed design. These two aspects are causally independent. In this situation we worked out a heuristic experimental, performance-driven and performance-based methodology that allows in an educated way to start with a coarse system model, with accurate expectations regarding its behavior. Through experiments these expectations are validated. We termed this methodology Incremental Experimentation, and demonstrated its use for our prototypal operating system MELODY.