MODELING STATUS AND EVENT BEHAVIOR OF INTERACTIVE SYSTEMS

Interactive systems involve both events which occur at specific moment s (e.g. keystrokes, mouse clicks and beeps) and more persistent status phenomena which can be observed at any time (e.g. the position of the mouse, the image on the screen). Most formalisms used for intereactiv e systems concentrate on one aspect or another, and may be asymmetric in their treatment of input and output. Notations and models for inter face specification are classified in the paper by the way they treat s tatus and event phenomena in their input and output. This is used to c onstruct a model and associated notation which incorporates both. By s pecifying examples using this model important design issues are highli ghted which would be missed if either status or event phenomena were n ot properly treated.