Object structures for real-time systems and simulators

The market for real-time applications has grown considerably in years, and in response engineering methods have also improved. Today's techniques, while adequate for building moderately complex embedded applications, are inadequate for building the large, highly reliable, very complex real-time applications that are increasingly in demand. To build such large systems, engineering teams need a more uniform, integrated approach than is available today. Ideally, the development approach would make uniform the representations of both application environments and control systems as they proceed through various system engineering phases. The ideal representation (or modeling) scheme should be effective not only for abstracting system designs but also for representing the application environment. It should also be capable of manipulating logical values and temporal characteristics at varying degrees of accuracy. This ideal modeling scheme is not likely to be realized through conventional object models. Although they are natural building blocks for modular systems, conventional object models lack concrete mechanisms to represent the temporal behavior of complex, dynamic systems. This article describes a real-time object structure that can flexibly yet accurately specify the temporal behavior of modeled subjects. This approach supports strong requirements-design traceability, the feasibility of thorough and cost-effective validation, and ease of maintenance.