Abstract:
PURPOSE: A service inference system in ubiquitous sensor network environment is provided to inference a service result by sensing a situation from a sensing value of the sensors. CONSTITUTION: A rule management unit(210) manages regulation. An ontology management unit(220) manages the ontology. A context management unit(230) receives the request of service from the application system. According to the flow of task, the context administration unit controls the execution of service. An ontology based deduction unit(240) reasons the necessary sensor in the service. A rule based deduction unit(250) deducts a reference value according to the deduced sensors. An information collecting unit(260) transfers the sensing value of sensors to the context administration unit.
Abstract:
PURPOSE: A method for estimating a join cost in XQuery through an XQuery join cost estimator is provided to efficiently process a join operation included in the XQuery by estimating a join operation cost through estimated selectivity. CONSTITUTION: An XQuery written by a user is analyzed(201), and selectivity of each node which is joined is estimated(202). Join cost of each node pair is estimated through the selection value of estimated each node(203). The total join cost is estimated through the estimated join cost(204). The XQuery is written for distributed XML(eXtensible Displayup Language) views. The XML view comprises each node occurrence information and cardinality information.