Application of SPEA2 algorithm in Web services selection

The problem of Web services selection based on quality of service (QoS) hasn´t be essentially solved by the single objective optimal algorithm which optimizes service selection by aggregating multiple QoS parameters to form a composite objective function using weighted scoring method. This paper presents a Web services selection algorithm of QoS-aware and global multi-objective optimization, termed WSSPEA2. The essence of the proposed algorithm is that the problem of Web services selection based on QoS is transformed into a multi-objective services composition optimization problem with QoS constraints. A strength Pareto evolutionary algorithm (SPEA2) is utilized to produce a set of Pareto-optimal solutions by means of simultaneously optimizing a series of objective functions, that is, minimizing service cost(C) and service time(T) with the constaint of satifying the parameters reputation(RE), reliability(R) and availability(A). And the users can select one from these solutions for their preferences. The results of a series of simulation experiments indicate the feasibility and efficiency of this algorithm.