  Computing becomes increasingly mobile and pervasive today; these changes
imply that applications and services must be aware of and adapt to their
changing contexts in highly dynamic environments. Today, building context-aware
systems is a complex task due to lack of an appropriate infrastructure support
in intelligent environments. A context-aware infrastructure requires an
appropriate context model to represent, manipulate and access context
information. In this paper, we propose a formal context model based on ontology
using OWL to address issues including semantic context representation, context
reasoning and knowledge sharing, context classification, context dependency and
quality of context. The main benefit of this model is the ability to reason
about various contexts. Based on our context model, we also present a
Service-Oriented Context-Aware Middleware (SOCAM) architecture for building of
context-aware services.
