An Approach To Adaptive Execution Of Composite Services Based On Service Interaction Model

Web services are the objects that deploy on the network, which build on XML and open Web technical specification. Web services have been widely used in the construction of large-scale distributed applications with good openness. Web service composition can build new complex application service by integrating a group of Web services with different functions by following certain rules. The new complex application service can provide a new value-added service for different requirements. However, larger challenges to guarantee Web service composition’s success rate and quality are coming because of the internet environment’s openness, dynamics and randomicity. Under the current network environment, manual adjustments of composite services are no longer able to satisfy the real-time requirements as the growth of the number of available services and the continuous changing functions and performances. As a result, that how to make composite services able to adjust themselves automatically according to targets on functionalities, performances and dependabilities for achieving higher level satisfaction has already been a critical problem in current service computing studies.This paper proposes an approach of environment adaptive execution of composite services based on service interaction model to solve problems caused by existing approachs of environment adaptive execution of composite services embed adjustment to Web service composition into executive process of Web service composition. First, on analyzing information involved in executive process of composite service, the service interaction model is extracted and defined. The service interaction model divide the executive process of composite service by horizontal and vertical. The independent executive units are generated to combine reactive and active adaptation strategies effectively. Then, organization model of alternative services based on service interaction model and dynamic execution model of composite service are given. Further, this paper proposes the mechanism to adjust executive plan dynamically of composite services based on service interaction model and the algorithm of service interactions initialization and service interactions dynamical adjustment. Then, this paper proposes the mechanism to execute dynamically of composite services based on service interaction model, including the algorithm of environment adaptive optimal selection of service interaction and the process of dynamical execution of composite services based on service interaction model. Finally, this paper provides a reflective framework based on the algorithm of environment adaptive execution of composite services based on service interaction model. A prototype system for adaptive composite services is implemented. Moreover, a test to cut video shows the effectivity of the proposed mechanism and approach.Comparing with most current environment adaptation approaches for composite service, with the service interaction model and mechanism of environment adaptive execution of composite services based on service interaction model, the approach in this paper divides the executive process of composite service by horizontal and vertical and combines reactive adaptations together with active adaptations, local optimizations together with gloable optimizations, and is able to select proper adaptation strategy to specific characters of environment variation. As a result, the flexibility and timeliness are both improved.