Designing for determinism: lessons learned from modern real-time avionics applications

Modern avionics application designs strive to achieve a balance between structure and computational resource utilization. With increasing degrees of integration and application complexity, designers devote considerable attention to structure and form, exploiting the abstraction capabilities of the Ada programming language. Use of design patterns, decomposition, and object construction techniques improve structural understandability and maintainability, but often at the expense of throughput and/or memory utilization. An examination of current design approaches for embedded data processing applications revealed patterns and design mechanisms that significantly reduce temporal determinism. In this paper, we provide a conceptual overview of the current state of practice within the Ada community by looking at design patterns and temporal mechanisms used in various applications and platforms. Alternative patterns and recommended approaches are developed which provide equivalent structural benefits, while improving determinism resource utilization efficiency