A relaxable service selection algorithm for QoS-based web service composition

ContextWeb Services are emerging technologies that enable application to application communication and reuse of autonomous services over Web. Composition of web services is a concept of integrating individual web services to conduct complex business transactions based on functionality and performance constraintsObjectiveTo satisfy user requirements, technologies of Quality of service (QoS)-based web service composition (QWSC) are widely used to build complex applications by discovering the best-fit web services in term of QoS.MethodIn this paper, a QoS-based service selection (RQSS) algorithm is proposed to help composite web application development by discovering feasible web services based on functionalities and QoS criteria of user requirements. The RQSS recommends prospective service candidates to users by relaxing QoS constraints if no suitable or available web service could exactly fulfill user requirements.ResultsA generic framework is implemented to demonstrate the feasibility and performance of RQSS by adapting WS-BPEL standards, and can be reused for QoS-based web composition applications.ConclusionThe experimental results show that the RQSS algorithm indeed performs well and increases the system availability and reliability.

► We propose a QoS-based service selection algorithm, called RQSS, to help the composite web application development.
► We relax the QoS constraints to recommend prospective service candidates if no suitable web services exist.
► We implement a framework which brings better performance, availability and reliability for RQSS applications.