Research on the Web Services Selection Problem

Based on service oriented infrastructures, there are many services that provide the same functionality but differ in quality parameters. An important issue for web services composition is how to select appreciates services from a set of alternatives with QoS features being considered. We define a Petri net model - WS_QPN to computer the QoS values of composite services. Since finding a solution for quality-driven services selection is NP-hard, strategies based on Genetic Algorithm are more suitable than traditional optimization techniques. We use a multiobjective evolutionary algorithm called NSGA-II to resolve this problem and discuss the coding schema and the objective functions obtained from WS_QPN.