TABLE OF CONTENTS Reactive Systems. Reactive Systems are defined by Harel and Pnueli (1985). Harel and Politi (1998) also give a brief but useful discussion.
Case Studies and Examples. The sources of the case studies are as follows. The Teaching Information System was done by some of my students for a company. The Electronic Ticket System is based on an example provided by Reif and Stenzel (1999). The heating tank controller is from Shlaer and Mellor (1992). The elevator controller example is ubiquitous. The tea-bag-boxing example is based on an example treated by Goldsmith (1993). The bug-fixing example is taken from Kovitz (1998). The Chemical Tracking System example is based on a case provided by Wiegers (1999, 102).
Systems and the Environment. The importance of the environment for systems design is pointed out in many texts on systems engineering, such as Blanchard and Fabrycky (1990), in which it appears as the concept of an open system, and in Stevens, Brook, Jackson, and Arnold (1998). These are also sources for the concepts of allocation and flowdown of properties, which is the basis for the systems engineering argument. Another source on this is Davis (1993). The concepts of allocation and flowdown appeared in bottom-up form, taking the viewpoint of the software engineer, in the requirements engineering reference model of Gunter, Jackson, and Zave (Gunter, Gunter, Jackson, and Zave 2000; Jackson 1995).
For reactive software systems, the environment is even more important than for general systems because the essential subject...
