The wide variety of devices currently available, which is bound to increase in the coming years, poses a number of issues for the design cycle of interactive software applications. Model-based approaches can provide useful support in addressing this new challenge. In this paper we present and discuss a method for the design of nomadic applications showing how the use of models can support their design. The aim is to enable each interaction device to support the appropriate tasks users expect to perform and designers to develop the various device-specific application modules in a consistent manner.

Abstract. This paper defines the problem space of distributed, migratable and plastic user interfaces, and presents CAMELEON-RT 1, a technical answer to the problem. CAMELEON-RT 1 is an architecture reference model that can be used for comparing and reasoning about existing tools as well as for developing future run time infrastructures for distributed, migratable, and plastic user interfaces. We have developed an early implementation of a run time infrastructure based on the precepts of CAMELEON-RT 1. 1

This paper addresses software adaptation to context of use. It goes one step further than our early work on plasticity [5]. Here, we propose a revision of the notion of software plasticity that we apply at the widget level in terms of comets. Plasticity is defined as the ability of an interactive system to withstand variations of context of use while preserving quality in use where quality in use refers to the ISO definition. Plasticity is not limited to the UI components of an interactive system, nor to a single platform: adaptation to context of use may also impact the functional core, it may have an effect on the nature of the connectors, and it may draw upon the existence of multiple platforms in the vicinity to migrate all or portions of the interactive system. A new reference framework that structures the development process of plastic interactive systems is presented to cover these issues. The framework is then applied at the granularity of widgets to provide the notion of a comet. A comet is an introspective widget that is able to self-adapt to some context of use, or that can be adapted by a tier-component to the context of use, or that can be dynamically discarded (versus recruited) when it is unable (versus able) to cover the current context of use. To do so, a comet publishes the quality in use it guarantees, the user tasks and the domain concepts that it is able to support, as well as the extent to which it supports adaptation.

With the explosion of devices, computing platforms, contextual conditions, user interfaces become more confronted to a need to be adapted to multiple configurations of the context of use. In the past, many techniques were developed to perform a task analysis for obtaining a single user interface that is adapted for a single context of use. As this user interface may become unusable for other contexts of use, there emerges a need for modelling tasks which can be supported in multiple contexts of use, considering multiple combinations of the contextual conditions. For this

www.dimi.uniud.it/giorgio Abstract. The paper discusses how accessibility helps in extending the range of goals that users (disabled or not) can achieve, and how it fails to increase user bandwidth for achieving those goals. The paper then illustrates how transcoders that satisfy a set of requirements, can effectively deal with the problem of generating, on the fly, specialized user interfaces that would support a more universal web access leading to a greater bandwidth. An informal analysis of a commercially available text-transcoder is used as an example of what can be done. 1.

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.

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VAQUITA allows developers to reverse engineer a presentation model of a web page according to multiple reverse engineering options. The alternative models offered by these options not only widen the spectrum of possible presentation models but also encourage developers in exploring multiple reverse engineering strategies. The options provide filtering capabilities in a static analysis of HTML code that are targeted either at multiple widgets simultaneously or at single widgets at a time, for their attributes and other manipulations. This flexibility is particularly important when the presentation model is itself used to migrate the presentation of the web page to other types of user interfaces, possibly written in different languages, in different computing platforms.

Abstract. Adapting a graphical user interface (GUI) to a variety of resources with different capabilities is one of the most interesting questions of today’s mobile computation. The GUI constructed for one application should be usable on different interactive devices, e.g. WebTV terminals, WAP phones or Java-enabled devices. In this paper, we discuss existing solutions and present a solution based on mobile agents. Mobile agents construct their GUI using third-party eXtensible User interface Language (XUL), jXUL middleware and XSL transformations. Mobile agents move to host computers and then build their GUI, or act as a proxy to devices without sufficient processing capabilities (e.g., WAP devices). The result is an adaptable GUI platform that can be run on multiple devices without modifications, supporting different resources and architectures. We show the application of this approach by implementing a mobile currency converter and survey. 1

ion, Control) [3] are both agent based models, where an agent is defined to have "state, possess an expertise, and is capable of initiating and reacting to events." [4]. An interface is built using hierarchies of agents. These agents represent an object in the application. In MVC, the model describes the semantics of the object, the view provides the (normally visual) representation of the object and the controller handles user input. In PAC, the abstraction describes the functional semantics of the object, the presentation handles the users interaction with the object, both input and output and the control handles communication between the presentation and the abstraction as well as between different PAC agents. The toolkit is object-oriented like both MVC and PAC, with each widget (or agent) encapsulated into different objects. Our toolkit, however, does not define the whole user interface in terms of a hierarchy of agents, but rather defines the individual widgets without specifying...