An Enhanced Ontology Based Context Model and Fusion Mechanism

With diverse sensors, context-aware applications which aim at decreasing people’s attentions to computational devices are becoming more and more popular. But it is inadequate just with sensors because what applications really need is high-level context knowledge rather than low-level raw sensor data. So a software layer which delivers high quality contexts to applications with an easy application programming model is needed. In this paper, we establish a formal context model using semantic web languages and design a context fusion mechanism which not only generates high-level contexts by reasoning, but also brings in context lifecycle management and periodically time based conflict resolution to improve the quality of contexts. Using the context fusion mechanism, a programmable and service oriented middleware is built upon OSGi framework to support context-aware applications. Also, we propose an application programming model using RDQL as context query language and demonstrate an application called Seminar Assistant. According to the experiment results, we believe our prototype system is useful for non-real-time applications in various domains.