Today's complex system environment and competitive economic environment demands precise answers to questions concerning dependability and quality. Current tools are not providing the ability to model complex fault handling scenarios and often require simplifying assumptions about failure rates, repair rates, and initial states which lead to incorrect solutions. Accurate dependability evaluations are a concern of both manufacturers and users of systems who often invest millions of dollars to keep systems operating correctly. A dependability tool that can address these concerns is in demand in both the commercial and military environments. In this program, researchers will develop a simulation tool based on "Rainbow Nets" which overcome limitations of previous net-based models by significantly reducing the model complexity. This reduction is achieved by hierarchical tokens, which can be created, destroyed, and have identities and features, and by transitions whose activation is governed by a set of rules or an algorithm. To demonstrate feasibility, this research will quantify improvements gained over existing techniques and provide several new dependability measures. In addition, specifications will be written for a commercially viable software tool. In general, this work will lead to a greater understanding of how faults affect computer systems.The potential commercial application as described by the awardee: The program will lead to the commercial development of a dependability evaluation tool that will be in demand by both manufacturers and users of complex systems to perform quantifiable quality assessments. This tool will provide a more accurate and more comprehensive dependability evaluation than any software tool currently available.
