Genetic Algorithm on Web Services Selection Supporting QoS
Cheng Zhang · Chinese Journal of Computers · 2006
A novel genetic algorithm is presented for Quality of Service (QoS)-aware Web services selection. The genetic algorithm includes a special relation matrix coding scheme of chromosomes that can express simultaneously all of composite paths, which can not be expressed simultaneously by the one dimension coding scheme. This matrix can also represent effectively the composite service re-planning and cyclic paths with the help of a simple method. Many composition scenarios can also be showed by the matrix but not by the one dimension. Elements along the main diagonal of the matrix are used to represent all tasks in all of composite paths and others elements in the matrix for the direct relationship between every two tasks. The proposed genetic algorithm running only once can construct the composite service plan according with the QoS requirements from a great deal of services compositions with different QoSes. Meanwhile, the algorithm adopts a mutation policy to improve the fitness. Experiments on QoS-aware Web services selection show that the genetic algorithm with this matrix can get more excellent composite service plan than the genetic algorithm with the one dimension coding scheme, and that the mutation policy plays a role at the improvement of the genetic algorithm fitness.