Seeking Quality of Web Service Composition in a Semantic Dimension

Ranking and optimization of web service compositions represent challenging areas of research with significant implications for the realization of the Web of Services vision. Semantic web services use formal semantic descriptions of web service functionality and interface to enable automated reasoning over web service compositions. To judge the quality of the overall composition, for example, we can start by calculating the semantic similarities between outputs and inputs of connected constituent services, and aggregate these values into a measure of semantic quality for the composition. This paper takes a specific interest in combining semantic and nonfunctional criteria such as quality of service (QoS) to evaluate quality in web services composition. It proposes a novel and extensible model balancing the new dimension of semantic quality (as a functional quality metric) with a QoS metric, and using them together as ranking and optimization criteria. It also demonstrates the utility of Genetic Algorithms to allow optimization within the context of a large number of services foreseen by the Web of Services vision. We test the performance of the overall approach using a set of simulation experiments, and discuss its advantages and weaknesses.