Structuring Architectural Topologies for Real-Time Safety-Critical Systems

This report describes an integrated approach to solving a particular system architecture design issue. Constructing architectures for safety-critical real-time control systems is a complex task. This complexity results from non-functional as well as functional requirements. The design issue of interest is that of setting a topology such that the dependability and timing characteristics of a system emerge during the design life-cycle. A topology is a set of conngured hardware and software units. This issue has hitherto been approached in a very simplistic manner. It is solved by deciding on a logical architecture and then setting an appropriate physical architecture. We investigate one aspect of the topology issue in depth; the architectural topology problem in which a number of alternative physical resources are employed to support a logical implementation (an architectural component) of a control action (Service). We show how a quantitative evaluation of alternative architectural topologies can be used to guide the process of building an architecture.