HaRTS: Performance-based design of distributed hard real-time software

Abstract

We introduce a hard real-time software development environment, called HaRTS, which consists of a performance-based design tool, three static scheduling tools, a code generator, and a visualization tool. HaRTS solves three problems: (1) how to specify a real-time system design that will capture hard deadline requirements and timing information as well as traditional control/data flow structure information; (2) how to decide, from the design, if the implementation will meet all deadlines, and (3) how to visualize the system as a running prototype so that design errors can be found before coding. The first problem is solved by adapting SADT/IDEFO to the real-time design domain. We do this by adding timing information to SADT-like graphical notation, and then analyzing the flattened diagram to derive a performance-based design. Problem two is solved by a new static scheduling algorithm that considers precedence-constrained tasks as well as hard deadlines. Problem three is solved by incorporating several novel visualization tools into HaRTS: dynamic Gantt charts, task graph animation, and processor animation. HaRTS has been successfully used to analyze and improve a number of real-time systems in navigation and flight control. Light-weight Ada task execution, combined with Ada code generation, make HaRTS a practical tool for design engineers.