Introducing Interoperable Geospatial Services to Present and ProcessSensor Observation (Case study: Tehran Air Quality Sensors)

The pressing environmental problem of urban air pollution in megacities is the most prominent issue for urban decision makers. An important cause of air pollution in Tehran, the capital of Iran, is the exhaust from about 2 million motor vehicles operating in an extremely congested road space, as well as 70,000 industrial units. The dissemination of air quality information can be efficient in controlling ambient air pollution and minimizingrelated health threats. Public access to up-to-date and reliable data is considered as one of the key components of a successful environmental management. Moreover, it is necessary to provide on-demand processing functionalities in the context of environmental modelling. These requirements can be met by establishing suitableenvironmental monitoring systems. Such systems are data-intensive and time-sensitive. They need to exchange and process heterogeneous data among multiple sensors deployed in a sensor network. Data from such sensors play an important role to improve notifying the pollution sources, preventing the health threats, and reducing thenumber of people affected by environmental pollution. But, the use of such data is hampered in many ways. Lack of easily available and usable metadata about the presence and capabilities of sensors, lack of common data formats that can be used by data producers and data consumers, lack of interoperability between disseminationand acquisition systems, and lack of interoperability between processing systems are among technical challenges in this context. In this research, we address these aforementioned technical challenges through developing a service-oriented architecture to facilitate accessing, processing, and visualizing the different types of sensors andobservations. We discuss how the use of Web services technology and OGC framework can address such geospatially oriented challenges in an open and standard way. We have designed and implemented standardsbased, interoperable services that provide sensor observation delivery mechanism and processing capabilities in environmental monitoring context. The services were deployed in a Web-based environmental monitoring systemapplication so-called Tehran Air Quality Reporter. It provides real-time air quality information through a Sensor Observation Service and generates on-demand air pollution maps using a Web Processing Service. The standard specifications of the SWE and the WPS standard interface along with Web services technology were used toimplement the components of the proposed system. The use of such standards can provide interoperability among geospatial processing systems. Since sensor observation data are offered to users in O&M and map generation process result provided in KML, data interoperability is achieved. Furthermore, as Web service technologies along with SOS and WPS interfaces are utilized for the development of the system, no problems regarding the interaction between clients and the services deployed in server side is observed. Microsoft. NET Framework 3.5 was utilized to implement the server-side components of the proposed system. Web client technologies (Dynamic HTML, CSS, and JavaScript) were used in the client-side to provide user-friendly environment. AJAX