A calculus for dynamic customization of virtual environments

Abstract

Two problems in the design and deployment of multimedia applications are the lack of design-time and run-time flexibility. In this paper we discuss a general methodology for tackling these issues. The work presented here is an extension of the AlphaOmega framework of [4]. In that framework we showed how the intuitive notion of an object representing its properties and capabilities to other objects differentially could be exploited to provide a powerful but easy way to change the behavior and interfaces of an application, dynamically if desired. In this paper, we develop a formal approach to the basic principles of the AlphaOmega framework. This leads to the definition of a formal system called the αω-calculus. The αω-calculus identifies a set of programming language abstractions that can be consistently added to any object-oriented language. While the calculus captures the intuitive notions underlying the AlphaOmega framework, it also goes beyond the original framework in power and flexibility. We demonstrate the generality of our approach by working with an example that shows how it provides unifying abstractions for such seemingly diverse domains as interactive distance learning and various issues in the area of multimedia documents.