Structuring Criteria for Real Time System Design

Abstract

This paper discusses and compares the criteria used by different design methods for decomposing a real time system into tasks and modules. The criteria considered are coupling, cohesion and information hiding for module structuring and concurrency for tasks. The Structured Design method uses the module coupling and cohesion criteria. The NRL method and Object Oriented Design use information hiding as the primary criterion for identifying modules and objects respectively. The Darts design method uses a set of task structuring criteria for identifying the concurrent tasks in the system. A new design method for real time systems is introduced that uses both task structuring and information hiding module structuring criteria. The method is described and illustrated by means of an example of an automoble cruise control system.