A Survey on Semantic Sensor Web: Sensor Ontology, Mapping and Query
International Journal of u- and e- Service, Science and Technology
Sensor Network has been widely used in all fields, and a large number of heterogeneous data is produced. In order to make these data shared and integrated semantically, semantic web technology is introduced in the sensor network. In this paper, we make a comprehensive survey about Semantic Sensor Web (SSW) from the perspective of ontology, mapping and query respectively. Firstly, we present state of the art of SSW from three aspects: ontologies before SSN ontology, SSN ontology and the
... gy and the extensions of SSN ontology, in which the extensions of SSN ontology are introduced emphatically. Secondly, we discuss the mapping from the stream data to ontology and focus on the comparison of the mapping languages in order to find out the best mapping method of SSW. Thirdly, we describe the research status of stream data query languages and analyze the characteristics, the application fields, the related researches and tools of the query languages in detail. Finally, the future research directions of SSW are proposed. 326 Copyright ⓒ 2015 SERSC (5) The description capability, the sharing and reuse capability of the sensor data can be increased. In this review, we investigate the related work of Semantic Sensor Web in recent years especially from the ontology, mapping and query perspective to show the state of the art and future research directions in this area. The development of sensor ontologies is introduced and the SSN ontology and the extensions of SSN ontology are discussed emphatically. Meanwhile, the comparison criteria for the ontologies are given. Mapping methods which from stream data to the ontology are analyzed and the mapping languages are compared. Semantic query methods of stream data based on ontology are discussed. The comparison of query languages is done according to the comparison criteria which are presented in this paper. Finally, the future research directions of Semantic Sensor Web are presented. The reminder of this paper is organized as follows. Section 2 presents the problem description of this article. Section 3 reviews the state of the art of the sensor ontology. Section 4 describes the mapping from stream data to ontology. Section 5 introduces query languages of the sensor data, and compares their different. Section 6 gives the future research directions of the Semantic Sensor Web. The Problem Description Semantic Sensor Web has been a hot area of research for several years. W3C founded the "Semantic Sensor Web" incubator working group which aimed to create and define ontology knowledge of sensor and sensor network and formulate semantic markup language based on service applications of the sensor network  . Semantic Sensor Web is the combination of the semantic web technology and sensor network which uses declarative descriptions of sensors, networks and domain concepts to search, query and manage the network and sensor data. On the other hand, it is an OGC-style sensor web enriched with semantic annotation, querying and inference  . In this paper, we present architecture of Semantic Sensor Web which uses three layers of semantics and technology to provide services, and it is showed in Figure 1 . They are the sensor data source layer, the data integration layer and the application layer. The contents of the three layers are introduced in details in the fallowing.