A self-adaptive query service for pervasive environments

The query service is the key element enabling users to identify and access data or services. If the growth of mobility in recent years makes it necessary to support different types of queries (continuous, location dependent, spatio-temporal, etc.,), it has also resulted in the emergence of new and specifique evaluation and optimization techniques. These different types of queries or techniques are useful and efficient depending on the usage conditions in which the user is located. Today, it is necessary to have, in pervasive environments, a query service that adapts to context changes (application constraints, user preferences, connectivity profile mobility, etc.). In this paper we propose an architecture of a query service dynamically adaptable to the context. This adaptability is managed and controled by an adaptation manager by use of rules. Our solution not only allows the addition and removal of new features dynamically, it also allows the change of used evaluation techniques in order to use the adapted one to the environment.