Real-time systems are becoming increasingly important to everyday life. Examples include command and control systems, process control systems, telecommunication systems, patient monitoring systems, flight control systems, robotics, avionics systems, and so on. With increasing computing power and high demand for multimedia applications, larger and more complex real-time systems are being continuously developed. However, the development of real-time systems is difficult and takes longer time than the development of a system without real-time constraints, and a significant portion of the entire effort remains devoted to the maintenance activities of the software life cycle. The concept of software architecture has recently emerged as a new way to improve our ability to effectively construct large- scale software systems. In spite of many attempts to develop architecture specification languages, this area still lacks a solid formal foundation. Without a solid foundation, it is difficult to develop and apply rigorous analysis methods to assure the correctness of real-time software systems as well as to analyze the impacts of changes on various system properties such as safety, consistency, and reliability. This research seeks to develop a formal foundation for an architecture specification language using the integration of non-monotonic logic and temporal logic. The syntax of the language is based on the concepts of object, frames and production rules. This allows developers to easily describe the attributes and constraints of each software component, and also the hierarchical relations among the software components in the software architecture. The goal is to localize changes to software components in the low- level architecture specification and avoid modifying the high- level architecture specification. The semantics of multiple inheritance and exception handling will be established using a non-monotonic logic. Based on the formal foundation of the architec ture specification language, it is expected that new possiblities will exist for analyzing software properties such as liveness, safety, consistency, and temporal constraints. This foundation is also expected to provide a basis for analyzing the impact of changes to a real-time software system. ***
