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Milestone Year
1984
Statecharts and reactive systems
In 1984, WIS scientists devised a visual formalism called "Statecharts" to deal with the problem of describing the behavior of reactive systems clearly and rigorously. The term "reactive systems" was coined by WIS scientists in 1986, and it refers to systems in which the complexity arises from often unpredictable interactions of the systems with its environment, and/or between the various subsystems. Such systems are the most difficult ones to deal with in software and systems engineering, and Statechart provided a firm basis for designing and analyzing them in a reliable manner.
Statecharts are a grand extension of classical state transition diagrams, and are both visual/diagrammatic and mathematically precise. They lead to algorithms for their direct execution or for their automatic transformation into executable code. Tools co-designed by WIS scientists for these tasks include Statemate and Rhapsody, which are now marketed by IBM. The language and its supporting tools are in wide use in a variety of applications, including automotive, aerospace, medical instrumentation, interactive software, and much more. WIS scientists have also been involved in using Statecharts and their underlying tools to model biological systems, and more recently also systems from the social sciences.
