Abstract: To supply context-aware applications with a variety of sensed or inferred context information, a powerful context query mechanism is needed. Depending on context representation and storage models, this chapter presents and analyzes seven typical kinds of context query languages and mechanisms (i.e., Structured Query Language (SQL) based, eXtensible Markup Language (XML) based, ontology based, event based, logic based, programming application program interface based, and graphic interface based). Their supports for context heterogeneity and context reasoning, as well as applicable users, are compared and analyzed.
6.1Seven Context Query Mechanisms
Acquired context information is either kept in a context database, which ...