Forecasting real-time behavior during software design using a CASE environment

Real-time software is required to react within certain time constraints. To forecast early in the design process whether or not the design approach chosen will fulfil those time constraints without costly prototyping, two methods have been developed: open-loop dynamic evaluation of time-critical parts of executable design specifications, and animating a closed-loop system, consisting of the executable design specifications coupled to a dynamic simulation model of the physical system involved. Both methods are explained using examples. In both methods, instead of constructing a simulation model of the software to be produced, the design representation itself is used as a `simulation model´. By integrating these methods in the CASE (computer-aided software-engineering) environment EPOS, real-time software technology has been brought closer to the aim of automating the software-development process. A major drawback of the methods is that the quality of the forecasts depends on the quality of the estimates of time durations and thus on the experience of the software engineers