QoS-based web service composition in an environmental assessment system

In the Intelligent, Distributed Environmental Assessment (IDEA) system [1], sensors are used to measure the noise and air pollution. These sensors can be fixed, or mobile. The architecture is service-oriented; this allows application architects to combine services provided by the IDEA platform for satisfying application needs. Web services exposed by the sensor nodes provide functionalities such as data transmitting, data processing, and data aggregation. A typical application may require a set of those services. Because of the sensor nodes´ resource limitation, some services may not keep QoS levels stable for a long duration which could cause a global QoS failure of the composite service. In this paper, we propose an approach which addresses the problem of web service composition for the IDEA platform. This approach relies on an evaluation of QoS values in order to find the best-suited composite service for each request.