QoS-aware Web Service Composition Considering the Constraints between Services

In the field of Web service composition, many scholars consider that there is no connection between concrete services but actually there are conflicts and dependencies between different types of services. For addressing the problem of QoS-aware Web service composition which considers conflicts and dependencies between services, a chaos genetic algorithm (CGA) is proposed. In this paper, chaos theory is used to generate the initial population of the genetic algorithm. As well as the repair strategy is used to deal with the individuals in the initial population that violate different constraints. After selection, crossover and mutation operations, the algorithm may produce infeasible individuals that violate the constraints between services, and hence new fitness function is needed to deal with the issue of that population has infeasible individuals. And then small degree chaotic disturbance is imposed to the population, which can help genetic algorithm to jump out of local optimum and can speed up the convergence. Experimental results demonstrate the effectiveness of the proposed algorithm.