User interface system based on active objects

Abstract

An active-object user interface system (AOUIS) is a user interface system implemented as an active object system (AOS). An AOS is a transition-based object-oriented system suitable for the design of various concurrent systems. In an AOUIS, user interface objects , which are sometimes called "widgets", are represented as active user interface objects (AUIOs). The behavior of an AUIO is defined by the transition rules, the equational assignment statements, and the event routines provided in its class definition. Furthermore, an AUIO can be constructed from its component AUIOs through structural composition as if it were a hardware object. Thus, AUIOs are better encapsulated and provide more flexible communication protocols than ordinary user interface objects. In addition, declarative descriptions of multiple views can be provided for each AUIO.