1 research outputs found
Checking Behavioral Consistency Constraints for Pervasive Context in Asynchronous Environments
Context consistency checking, the checking of specified constraint on
properties of contexts, is essential to context-aware applications. In order to
delineate and adapt to dynamic changes in the pervasive computing environment,
context-aware applications often need to specify and check behavioral
consistency constraints over the contexts. This problem is challenging mainly
due to the distributed and asynchronous nature of pervasive computing
environments. Specifically, the critical issue in checking behavioral
constraints is the temporal ordering of contextual activities. The contextual
activities usually involve multiple context collecting devices, which are
fully-decentralized and interact in an asynchronous manner. However, existing
context consistency checking schemes do not work in asynchronous environments,
since they implicitly assume the availability of a global clock or relay on
synchronized interactions.
To this end, we propose the Ordering Global Activity (OGA) algorithm, which
detects the ordering of the global activities based on predicate detection in
asynchronous environments. The essence of our approach is the message causality
and its on-the-fly coding as logic vector clocks in asynchronous environments.
We implement the Middleware Infrastructure for Predicate detection in
Asynchronous environments (MIPA), over which the OGA algorithm is implemented
and evaluated. The evaluation results show the impact of asynchrony on the
checking of behavioral consistency constraints, which justifies the primary
motivation of our work. They also show that OGA can achieve accurate checking
of behavioral consistency constraints in dynamic pervasive computing
environments.Comment: 9 pages, 9 figure