What is Pervasive Computing?

To the inspired observer, computer science nowadays appears to be challenged (and driven) by technological progress and quantitative growth. Among the technological progress challenges are advances in sub-micron and system-on-a-chip designs, novel communication technologies, microelectro-mechanical systems, nano and materials sciences. The vast pervasion of global networks over the past years, the growing availability of wireless communication technologies in the wide, local and personal area, and the evolving ubiquitous use of mobile and embedded information and communication technologies are examples for challenges posed by quantitative growth. We perceive a shift from the “one person with one computer” paradigm, which is based on explicit man machine interaction, towards a ubiquitous and pervasive computing landscape, in which implicit interaction and cooperation is the primary mode of computer supported activity. This change – popularly referred to as “Pervasive Computing” – poses serious challenges to the conceptual architectures of computing, and the related engineering disciplines in computer science. In this work, I will reflect on some of the emerging pervasive and ubiquitous computing trends and potentials, and in particular on the software engineering issues associated with the provision of context aware systems. Historical Background “The most profound technologies are those that disappear. They weave themselves into the fabric of everyday life until they are indistinguishable from it“ was Mark Weiser’s central statement in his seminal paper [Weis 91] in Scientific American in 1991. His conjecture, that “we are trying to conceive a new way of thinking about computers in the world, one that takes into account the natural human environment and allows the computers themselves to vanish into the background” has fertilized the embedding of ubiquitous computing technology into a physical environment which responds to people’s needs and actions. Most of the services delivered through such a “technology-rich” environment are services adapted to context, particularly to the person, the time and the place of their use. Along Weiser’s vision, it is expected that context-aware services will evolve, enabled by wirelessly ad-hoc networked, mobile, autonomous special purpose computing devices (i.e. “smart appliances”), providing largely invisible support for tasks performed by users. It is expected that services with explicit user input and output will be replaced by a computing landscape sensing the physical world via a huge variety of sensors, and controlling it via a manifold of actuators in such a way that it becomes merged with the virtual world. Applications and services will have to be greatly based on the notion of context and knowledge, will have to cope with highly dynamic environments and changing resources, and will need to evolve towards a more implicit and proactive interaction with users. A second historical vision impacting the evolution of pervasive computing claimed for an intuitive, unobtrusive and distraction free interaction with technology-rich environments. In an attempt of bringing interaction “back to the real world” [WMG 93] after an era of keyboard and screen interaction, computers started to be understood as secondary artefacts, embedded and operating in the background, whereas the set of all physical objects present in the environment were started to be understood as the primary artefacts, the “interface”. Instead of interacting with digital data via keyboard and screen, physical interaction with digital data, i.e. interaction by manipulating physical artefacts via “graspable” or “tangible” interfaces, was proposed. Inspired by the early approaches of coupling abstract data entities with everyday physical objects and surfaces like Bishop’s Marble Answering Machine, Jeremijenko’s Live Wire and Wellner’s Digital Desk [WMG 93], tangible interface research [GOI 98] has evolved, where physical artefacts are considered as both (i) representations and (ii) controls for digital information. A physical object thus represents information while at the same time acts as a control for directly manipulating that information or underlying associations. With this seamless integration of representation and control into a physical artefact also input and output device fall together. Placed meaningfully, such artefacts can exploit physical affordances suggesting and guiding user actions, while not compromising existing artefact use and habits of the user. Recent examples for “embodied interaction”, where input and output are fused into physical object manipulation, include architecture and landscape design and analysis [PRI 02], object shape modeling interfaces using brick like blocks or triangular tiles [GOI 98]. Although the first attempts of the ubiquitous and pervasive computing vision in the early nineties fell short due to the lack of enabling hardand software technologies, are now, about ten years later, viable due to technological progress and quantitative growth. Pervasive computing initiatives and projects have emerged at major universities worldwide, and national and international research funding authorities (IST Future and Emerging Technologies programme of the EU, DARPA, NSF, etc.) have accelerated the efforts of a rapidely growing, vibrant research community. Preliminarily suffering from a plethora of unspecific terms like “Calm Computing”, “Hidden or Invisible Computing”, “Ambient Intelligence”, “Sentient Computing”, “Post-PC Computing”, “Universal Computing”, “Autonomous Computing”, “Everyday Computing”, etc., the research field is now consolidating from its foundations in distributed systems and embedded systems, and is starting to codify its scientific concerns in technical journals, conferences, workshops and textbooks. This process, however, is by far not settled today, so that even the term “Pervasive Computing” must be regarded verdant.