Licia Capra, Wolfgang Emmerich and Cecilia Mascolo
Dept. of Computer Science,
University College London
Dept. of Computer Science
Gower Street, London, WC1E 6BT UK
Abstract:
Mobile devices, such as mobile phones and personal
digital assistants, have gained wide-spread popularity.
These devices will increasingly be networked, thus enabling
the construction of distributed applications that have
to adapt to changes in context, such as variations in network
bandwidth, battery power, connectivity, reachability
of services and hosts, and so on. In this paper, we describe
CARISMA, a mobile computing middleware which exploits
the principle of reflection to enhance the construction of
adaptive and context-aware mobile applications. The middleware
provides software engineers with primitives to describe
how context changes should be handled using policies.
These policies may conflict. We classify the different
types of conflicts that may arise in mobile computing
and argue that conflicts cannot be resolved statically at the
time applications are designed, but, rather, need to be resolved
at execution time. We demonstrate a method by
which policy conflicts can be handled; this method uses a
micro-economic approach that relies on a particular type
of sealed-bid auction. We describe how this method is implemented
in the CARISMA middleware architecture, and
sketch a distributed context-aware application for mobile
devices to illustrate how the method works in practise. We
show, by way of a systematic performance evaluation, that
conflict resolution does not imply undue overheads, before
comparing our research to related work and concluding the
paper.
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Updated on: 29/05/2003
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