The increasing complexity of pervasive computing environments puts the current software development methods to the test. There is a large variation in different types of hardware that need to be addressed. Besides, there is no guarantee the environment does not evolve, making the software developed for the initial environment deprecated and in need for updates or reconfiguration. Software deployed in such an environment should be sufficiently dynamic to cope with new environment configurations, even while the system is in use. This goes beyond coping with new contexts of use and building context-aware systems: while most approaches are mainly focused on how the software behavior adapts according to the changing context in a fixed environment, our approach, ReWiRe, allows the environment configuration to change over time.

Users often become frustrated when they are unable to understand and control a pervasive computing environment. Previous studies have shown that allowing users to pose why and why not questions about context-aware applications resulted in better understanding and stronger feelings of trust. Although why and why not questions have been used before to aid in debugging and to clarify graphical user interfaces, it is currently not clear how they can be integrated into pervasive computing systems. We explain in detail how we have extended an existing pervasive computing framework with support for why and why not questions. This resulted in PervasiveCrystal, a system for asking and answering why and why not questions in pervasive computing environments.

Abstract. In this paper we show an approach that allows web interfaces to be dynamically distributed among several interconnected heterogeneous devices in an environment to support the tasks and activities the user performs. The approach uses a light-weight HTTP-based daemon as a distribution manager and RelaxNG schemas to describe the service user interfaces offered by native applications. From these service descriptions, the XHTML-based user interface is generated.

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