QoS oriented web service composition and optimization in SOA

In recent years, web services have developed rapidly along with the amazing development of SOA, while many web services provide the same function. Thus, it has been attracting substantial attention that how to choose web services to make a service composition in order to satisfy the business needs in SOA. At present, whether the service composition can meet the Quality-of-Service (QoS) needs of the users or not becomes an important criterion. However, existing research methods overlooked the effect of business process structure on the QoS of service composition. Business process is made by the users according to the business needs and describes the way to call web services, the structure of which affects the calculation of QoS in service composition. This paper proposes an algorithm of QoS oriented web service composition and optimization based on the initial business process structure made by the users. The algorithm optimizes the initial service composition plan repeatedly in dependence on the difference of merging methods for each QoS property in different business process structures. The effect of the algorithm to optimize the service composition was given in a series of experiments.