Research And Implement For Sensor Observation Service Based On SWE

Currently, there is a wide range of sensor networks, but due to the lack of interoperability of the sensor networks, specific sensor network can only be accessed by specific applications which have caused a serious waste of resources. Because of the heterogeneity of the sensor network, different way of information exchange and diverse of communication format, it is extremely difficult to achieve a kind of common, efficient and flexible services to obtain sensor observations data. Thus the main purpose of this paper is to design an open architecture of the sensor observation services through researching sensor observation services based on SWE,and then design and implement sensor observation services prototype system on the basis of the architecture. The goal of the prototype system is to make users obtain observational data from heterogeneous sensor networks by calling sensor observations service through the Internet without any prior knowledge of the sensor.This paper first systematically describes theory of sensing observation services based on SWE, including the SWE architecture, the core function of sensor observation services and the discovery and registration mechanism of sensor observation services. It also briefly introduces the present research situation of home and abroad on this field.Secondly, it describes the process of the design of the sensor observation services prototype system in detail, and presents an open and layered structure of sensor observation services. A service-oriented idea has been introduced in the design of this architecture, so that the system is suitable for distributed environments and supports software reuse. Abstract factory design pattern has been adopted in the data layer in order to facilitate expansion of the sensor networks and database system. Sensor observation services prototype system is builted based on the information model of SWE, and XML-based observational data binding technology has been adopted to implement the sensors and sensor observations XML document access operations.Then key technologies are emphasized, which implement sensor observation services prototype system, including the key technology about the realization of the core class of the system business logic layer and data layer class, business processes and the whole database structure of the prototype system. Prototype system has implemented the function of the three core operations of the OGC's SOS, including obtaining description metadata documents of the services, sensor observation data and description metadata documents for sensors. With Java web services used in the implementation of the system, only external interfaces has been provided instead of showing the details. Remote clients can easily invoke the sensor observation services to obtain the required observed data by the WSDL address of the SOS service. Finally, in order to confirm the function of the prototype system, it made experiments that utilize the SOS prototype system to collect sensor observation data in a real building monitoring wireless sensor networks. Experimental results show that the core operating of SOS implemented in the SOS prototype system could do the data collection service well.