Dr Mohammed Salifu
The Open University
Department of Computing
Walton Hall
Milton Keynes
MK7 6AA
Phone: +44-1908-653778
Email: M.Salifu@Open.ac.uk

Context-aware applications monitor changes in their environment and switch their behaviour so as to continue satisfying requirements. Monitoring all contextual variables, however, may lead to runtime inefficiency. Similarly, non-essential switching may also lead to inefficiency.  Therefore, we propose to select the contextual variables that are sufficient to determine the satisfaction of requirement in varying contexts and to use requirements trade-off analysis to reduce non-essential switching.

Theoretically, we are developing a problem-oriented approach that partitions contextual variability into a set of contextual variables, and contextual dependencies into perspectives that we represent as a set of variant sub-problems. We use abstraction to bring the perspectives into a problem that can be analysed in a wider context.

Technically, we use the problem frames semantics to capture problem variants which are subsequently used to derive the required monitoring and switching problems. We encode the problem of deriving adaptive monitoring and switching specifications into propositional logic problem statements that is solved using a SAT solver embedded in a dependency re-factoring algorithm using a host programming language.

A different facet of the monitoring and switching problems is that of eliciting and reasoning about behavioural monitoring and switching concerns such as initialisation, interference, synchronisation, etc, induced by varying context when software switches from one behaviour to another following a detection of requirement violation. The derivation of these concerns in problem descriptions forms part of our primary research goals.






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