This paper introduces the Abstract User Interface (AUI) model and notation for specifying abstract interaction in interactive software systems with graphical, direct manipulation user interfaces. The AUI model is aimed at improving the plasticity of an interactive system. An interactive system is considered to be plastic when it is easily adaptable to concrete user interface styles. To support plasticity, an AUI specification defines the interaction between input, output and computation in terms of the abstract elements of the user interface: a relation we refer to as abstract interaction. Concrete characteristics of the user interface, such as events, callbacks and rendering, are deliberately factored out so that the abstract interaction relation can be exposed. Clearly defining the abstract interaction ensures that consistent interaction semantics is maintained independent of changes to the concrete user interface. To demonstrate the AUI concept, a range of user interface styles are presented for a single AUI specification of a drawing tool, and examples of commercial applications are presented.

Using model- and language-based tools to develop plastic applications requires developers to become familiar with abstract modeling concepts or difficult language syntax. This is a departure from traditional visual interface development tools, in which developers select the widgets that will appear in the application and write the code that defines the widgets’ functionality. We present WAHID, a widget-level approach to plasticity in both new and legacy applications that conforms to traditional interface development techniques. WAHID provides internal and external architectures for integrating plastic widgets in an application. The internal architecture provides plasticity in new applications and requires that the application code be available for the architecture to be deployed. The external approach uses gesture handling for widget activation in legacy applications. We demonstrate the viability of these architectures through example scroll bar and menu widgets.

With the proliferation of consumer computing devices with varied display and input characteristics, it has become desirable to develop interactive systems that are usable across multiple physical environments without requiring costly redesign and reimplementation. Interactive software that easily adapts to new computer systems and environments while maintaining its usability is said to be `plastic'. This paper introduces the AUI programming language that was designed specifically to support the development of plastic interactive software.

Today most commercial database management software is extended to store and manage multimedia objects beside standard alphanumeric data. In this paper we study how such universal database systems can be used for implementing an adaptive multimedia digital library. We present a framework for e#cient and #exible delivery of multimedia content based on the idea that multimedia objects are often stored redundantly to support broadest system access for diverse clients from heterogenous environments. There is a large number of alternatives for universal database systems to store and deliver multimedia data, since storage formats are not independent from each other but heavily interrelated by conversion tools. Partitioning the data formats into those that are physically stored in the database and those that are converted into a delivery format on-demand poses a nontrivial optimization problem. The framework presented here tackles this problem and has been implemented and evaluate...