... user interface design and development: user interfaces must now accommodate the capabilities of various access devices and be suitable for different contexts of use, while preserving consistency and usability. We propose a set of techniques that will aid UI designers who are working in the domain of mobile computing. These techniques will allow designers to build UIs across several platforms, while respecting the unique constraints posed by each platform. In addition, these techniques will help designers to recognize and accommodate the unique contexts in which mobile computing occurs. Central to our approach is the development of a user-interface model that serves to isolate those features that are common to the various contexts of use, and to specify how the userinterface should adjust when the context changes. We claim that without some abstract description of the UI, it is likely that the design and the development of user-interfaces for mobile computing will be very time consuming, error-prone or even doomed to failure.

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In ubiquitous computing environments, multiple users work with a wide range of different devices. In many cases, users interact and collaborate using multiple heterogeneous devices at the same time. The configuration of the devices should be able to change frequently due to a highly dynamic, flexible and mobile nature of new work practices. This produces new requirements for the architecture of an appropriate software infrastructure. In this paper, an architecture designed to meet these requirements is proposed. To test its applicability, this architecture was used as the basis for the implementation of BEACH, the software infrastructure of i-LAND (the ubiquitous computing environment at GMD-IPSI). It provides the functionality for synchronous cooperation and interaction with roomware components, i.e. room elements with integrated information technology. In conclusion, our experiences with the current implementation are presented.

Abstract. The increasing proliferation of computational devices has introduced the need for applications to run on multiple platforms in different physical environments. Providing a user interface specially crafted for each context of use is extremely costly and may result in inconsistent behavior. User interfaces must now be capable of adapting to multiple sources of variation. This paper presents a unifying framework that structures the development process of plastic user interfaces. A plastic user interface is capable of adapting to variations of the context of use while preserving usability. The reference framework has guided the design of ARTStudio, a model-based tool that supports the plastic development of user interfaces. The framework as well as ARTStudio are illustrated with a common running example: a home heating control system. 1

This paper introduces and describes the notion of graceful degradation as a method for supporting the design of user interfaces for multiplatform systems when the capabilities of each platform are very different. The approach is based on a set of transformational rules applied to a single user interface designed for the less constraint platform. A major concern of the graceful degradation approach is to guarantee a maximal continuity between the platform specific versions of the user interface. In order to guarantee the continuity property, a priority ordering between rules is proposed. That ordering permits to apply first the rules with a minimal impact on the multiplatform system continuity.

Increased interest in universal usability is causing some researchers to study advanced strategies for satisfying first-time as well as intermittent and expert users. This paper promotes the idea of multi-layer interface designs that enable first-time and novice users to begin with a limited set of features at layer 1. They can remain at layer 1, then move up to higher layers when needed or when they have time to learn further features. The arguments for and against multi-layer interfaces are presented with two example systems: a word processor with 8 layers and an interactive map with 3 layers. New research methods and directions are proposed.

Mobile computing offers the possibility of dramatically expanding the versatility of computers, by bringing them off the desktop and into new and unique contexts. However, this newfound versatility poses difficult challenges for user-interface designers. We propose three modelbased techniques that will aid UI designers who are working in the domain of mobile computing. These techniques will allow designers to build UIs across several platforms, while respecting the unique constraints posed by each platform. In addition, these techniques will help designers to recognize and accommodate the unique contexts in which mobile computing occurs. All three techniques depend on the development of a user-interface model which serves to isolate those features that are common to the various contexts of use, and to specify how the user-interface should adjust when the context changes. User-interface models allow automatic and automated tool support that will enable UI designers to overcome the challenges posed by mobile computing.

VAQUISTA allows developers to reverse engineer a presentation model of a web page according to multiple reverse engineering options. The alternatives 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.

this paper, we present a process and a software mechanism that support context changes for plastic user interfaces. We propose to structure adaptation as a three-step process: recognition of the situation, computation of a reaction to cope with the situation, and execution of the reaction. Reactions are specified in an evolution model which, in turn, is executed by a context supervisor. This supervisor is notified of context changes by a software probe that automatically detects deviations from the current situation. When notified, the supervisor executes the evolution model, and, when possible, adapts the user interface to the new context of use. Keywords: human computer interaction, plasticity, adaptation, context of use, platform, environment. 1 Introduction Recent years have seen the introduction of many types of access devices including Personal Digital Assistants (PDAs) and mobile phones (cf. Figure 1). Systems like CyberGuide (Abowd et al., 19

In this paper, a conceptual model for synchronous applications in ubiquitous computing environments is proposed. To test its applicability, it was used to structure the architecture of the BEACH software framework that is the basis for the software infrastructure of i-LAND (the ubiquitous computing environment at FhG-IPSI). The BEACH framework provides the functionality for synchronous cooperation and interaction with roomware components, i.e. room elements with integrated information technology. To show how the BEACH model and framework can be applied, the design of a sample application is explained. Also, the BEACH model is positioned against related work. In conclusion, we provide our experiences with the current implementation.