Extending SQL to support QoS and semantic data gathering in WSN

At high level, a sensor network can be modelled with a database view. Under such a view, declarative queries are the preferred way of interacting with sensor networks for data and information collection tasks. The most popular database query language is SQL that is based on a SELECT-FROM-WHERE theme. However comparing to traditional databases, sensor network database has its unique features like dynamic, approximate, unreliable, etc. Extensions to SQL query language are thus needed for uses in sensor networks. In this paper, two extensions to traditional SQL query language have been proposed, including QoS and semantics. QoS extensions allow an application to express the concerned factors during the planning and execution of a query. Semantic extensions enable the representation of high-level information on group activities of the objects in a sensor network. We describe the extensions and give some examples for illustration.