A Specication Technique for Building Interface Agents in a Web Environment

This papers explores some system design issues regarding the structuring and information o w of complex distributed virtual environments (VEs) containing one or more users and dialogue agents. A specication technique is proposed for modelling such systems. We dene a specication technique as a suite of interrelated specication languages. It is argued that specication techniques should support gradual design renemen t. There- fore, the proposed technique provides several detail levels of specication. Furthermore, the technique tries to explicitly address distributed implementation issues right from the start. Even prototypes made using the technique are suited for distributed usage. The basic idea behind the technique is that all physical objects, such as user interface com- ponents and objects in the VE, are modelled as separate software components. These are arranged in a specic structure, reecting the actual physical or conceptual structure of the objects. A change notication model is provided that enables each component to react to events from its local structural environment, including additions and removals of other com- ponents. The technique is illustrated by means of a Web-based multi-user VE incorporating an environment-aware dialogue agent. The example shows how such a system may be struc- tured in a natural way using the technique and may be specied concisely. The provided change notication model may be considered eectiv e, as it largely replaces the need to di- rectly pass messages between components. However, the still limited expressivity of the change notication model was sometimes found cumbersome, and needs to be improved.