DEVELOPMENT OF MIDDLEWARE LAYER SUPPORTING SENSOR OBSERVATION SERVICE FOR A SIMPLE WEATHER STATION

Heterogeneous sensor networks have been developed and implemented for agricultural purposes. Although they have shown adequate level of performance during individual applications, it is generally difficult to integrate them. In order to increase their inter-operability, it is important to follow a standard. The objective of this study is to develop a middleware layer supporting Sensor Observation Service (SOS) standard of Open Geospatial Consortium. An embedded system, integrated on a simple weather station with the ability to measure 6 meteorological parameters, was developed. The embedded system implemented three core operations of SOS – GetCapabilities, DescribeSensor, GetObservation – using the web service. The serviced data could either be an observation or description of the sensor system. In order to make SOS operate on an embedded system, various implementation techniques were used. As a result, the responses were well-formed and there was no syntax error. The response time was just 3.44 sec when 500 observations were delivered from two files. It seldom affected measurement process. In addition, the only thing to add new sensors was to update an ObservationCache class and template files. Therefore, the middleware layer was flexible to be applied on other sensor networks.