REENGINEERING COMPUTER-BASED SYSTEMS FOR ENHANCED CONCURRENCY AND LAYERING

This article presents a methodology for reengineering complex computer systems. An important aspect of the reengineering methodology is the mission-critical software architecture (MCSA), a hierarchical view of complex systems that includes the levels of task clusters, tasks, pack ages, procedures, and statements. Reverse engineering identifies syste m attributes at each level of the MCSA. After reverse engineering, the system's software design is restructured to increase layering and con currency, and code is generated to effectively use language constructs . Given the code of tasks and packages, program components are partiti oned into tightly coupled clusters, and clusters are assigned to hardw are processors. A key element of the reengineering methodology is a se t of concurrency metrics for guiding the transformation tasks. The met rics are defined at each level of the MCSA and enable the assessment o f concurrency within a component or a cluster, and also among componen ts and clusters. The reengineering methodology is illustrated via a co mplex Navy system called AEGIS. The article also presents a generic Ad a module, which serves as a template for reengineered AEGIS modules.