The Global Constraints Analysis For Web Services Composition

Web service is a new form of Internet software that can be universally deployed and invoked in standard protocol. Services from different providers can be integrated to provide composite services. Competition between service providers is more and more austere along with web services technology changing with each passing day. Usually, many different services belonging to the same type can all satisfy the customers' requirement, therefore, when composing services, we can select the service more meeting users' requirements. But, when composing services, for the sake of satisfying local restrict, the web service composition flow can't fulfill the global constraints. Consequently, the selected one satisfies the local constraints, but the whole flow composed of these services disagrees with the requirement. The flow constraint includes not only the local constraints but also the global constraints, such as the total time, the total cost, the total space. Users intended to make the flow satisfy the two aspects to get the best flow. Accordingly, we set up a web service quality model to satisfying the global constraints.The research is based on the IPVita - an intelligent travel platform. Because, there are a lot of services interrelated with traveling. What users cared most about is a perfect travel routine with series of services not a single service. The user demands a whole satisfied traveling flow. In the process of business flow, according to the global constraints, we formalize the web services to make the web service quality model. Consequently, according to the characteristic of different global constraints, we calculate and select the service satisfying global constraints.The main work and contribution of the paper is below:1. The paper analyses the service quality issue in selecting web service. Then, we put forward the web service quality model. This work is part of SmartFlow and carried out in IPVita.2. Based on the web service quality model, we modeled the issue of web service composition. The paper analyses the web service selecting issue in EPVita and defines measurement functions for service quality.3. In the new model, the paper brings forward the optimizing arithmetic for the global constraints issue in service selecting. It also adduces examples and gives separate compute formulas, and presents relevant arithmetic according to the non-functional properties of web service.