Optimal QoS-Aware Web Service Composition

The availability of many independent services on an open network opens the opportunity of composing individual instances to achieve complex functionality. Most often there are several possible compositions to achieve the same high- level functionality; the advantage of choosing one composition instead of another one may lie in the different quality of the composition, e.g., one might be cheaper, faster, or more reliable. In this paper, we focus on services described with XML documents and accessed via XML protocols, known as Web services, and enriched with semantic and quality of service (QoS) annotations. We propose an algorithm that, given a desired functionality, returns a composition of services from a repository with the optimal response time or throughput. Services are composed taking into account an ontology of operation names expressed in OWL. RuGQoS is the related implementation.