Introducing contextual objects in an adaptive framework for wide-area mobile computing

Abstract

The emergence of mobile computing combined with the increasing popularity of the Internet has introduced new challenges that are not addressed in traditional distributed systems. In particular, mobile computing is characterized by the extreme variability of the environment components such as network bandwidth, computing power, location, services available, etc. The goal of our work is to provide a framework to dynamically adapt applications to the continuous changes of mobile environments including physical constraints and more qualitative changes. As a basis of our work, we present in this paper the concept of contextual objects. This approach allows to express the dependencies of an object according to a number of contexts such as the time, the location or the physical aspects (available network bandwidth or computing power) in a changing environment. 1 I n t r o d u c t i o n In recent years, mobile computing has emerged as a promising class of systems and its importance is still growing: the increasing availability of wireless technology and mobile devices allows users to move around with their own computing environment. At the same time, the number of Internet users grows exponentially and facilities for accessing Internet are henceforth widespread available thereby increasing the need of ubiquitous network access. Supporting mobile users on the Internet is thus becoming essential and leads to new challenges which are not addressed in traditional distributed systems [8]. Although in a static environment system configuration and available resources remain unchanged, mobile computing is mainly characterized by the extreme variability of any kind of computing resources. To deal with the dynamic nature of mobility, tools allowing to adapt applications to such variations at any level (network, systems, resources and software) are needed. Many works have been proposed to achieve transparently either the masking of mobility at the network level or at the system level, or the adaptation to physical constraints. Most of these proposals are able to adapt themselves to mobile constraints but are not specific