Direct manipulation authoring of object behavior in an interactive graphical modeling environment

A direct-manipulation model-authoring environment called RAPIDS II is presented. Its graphical models are composed of object components that have associated behaviors. These behaviors include changing appearance in response to user actions, changing the value of an attribute associated with an object, changing the appearance of an object in response to attribute value changes in that object or in some other object, scheduling future changes in response to an event, and starting a process of continuous change. All of these behaviors are determined by behavior rules that are authored by experts in the device or system that is being modeled. The model-based interactive graphical simulations of RAPIDS II are driven by a specialized expert system shell that directly supports real-time effects in its inference engine. The rules can be composed using either a structure-sensitive text editor or a menu-driven rule composition system. Menu-based rule authoring can be used to describe the behavior of an object without typing