Aims

The aim of this chapter is to provide a motivation for studying the modelling of computing systems by discussing the challenges of developing correct software. On completion of this chapter, the reader should be aware of the main concepts to be presented in the book and know where to find the relevant material in the text.

Software

Software is pervasive, error-prone, expensive to develop and, as an engineering medium, extraordinarily seductive. Its seemingly infinite flexibility, increasing power and the absence of physical characteristics, such as weight, make it an ideal medium in which to express complex models which might not exist at all were it not for software. As a result, software is often developed for applications which are critical either to an enterprise's mission or to the quality of life of those with whom the system interacts.

Challenged by the variety and scale of software applications, the participants in the 1968 NATO Conference on Software Engineering foresaw a discipline of software development with a sound scientific basis [Naur&69]. Over the last 40 years, there is little doubt that enormous advances have been made in our ability to control software development. However, software projects continue to suffer from serious difficulties which can lead to the delivery of faulty goods that are over budget and behind schedule.

The rapid increase in processor power has naturally led to increasing demands being made on software and its developers. Software is almost always developed as part of a larger system involving computing hardware, special systems such as sensors and actuators, human-computer interfaces and human beings.