Select A Number Of Issues, Quality Of Service-based Web Services

As a distributed computing technology used to build the Service-Oriented Architecture (SOA), web service has good interoperability, self-description and modular features. And web service has become a focus of attention for both industry and academia because of the advantages on loose coupling, standardization, and highly integrated capacity etc. Considering that a single web service cannot meet the complicated requirements of users, combining the previous available web services into the new and more powerful incremental web services has been a hotspot in recent research. However, with the great development of web service, the number of web services increases rapidly. There are so many web services with identical or similar functions on internet, that the existing web service selection technology based on functional description is not able to solve this problem. Therefore, the web service selection technology based on Quality of Service (QoS) with price, response time, reputation and so on has attracted more and more people's attention recently.Firstly, this paper introduces the related technologies of web service, and carefully analyzes the traditional web service architecture model, in view of its lack of QoS description support, this paper puts forward a new extended web service architecture model, and according to that , an integrated QoS dynamic acquisition method (IQDAM) is proposed in this dissertation, and a concrete flow to obtain the QoS of web services in this method is provided. Further more, this paper particularly introduces some critical issues of IQDAM, such as a dynamic strategy with the combination of direct trust and recommendation trust, a QoS noise-suppressed processing method and so on. In addition, on the basis of traditional UDDI, the EQ-UDDI of IQDAM is described in three aspects, which consists of function structure, data model and database design.Secondly, considering that the QoS-based web service selection problem is a NP hard problem, based on the analysis of the advantages and disadvantages of genetic algorithm (GA) and simulated annealing algorithm (SA), a Self-adaptive Niche Genetic Simulated Annealing Algorithm (SNGSAA) is proposed, which can be applied to the QoS-based web service selection problem. This paper introduces the methods and steps of SNGSAA-based Web service selection algorithm in detail. By comparing with traditional genetic algorithm according to simulation experiments, this paper verifies the superiority of SNGSAA algorithm on the average of fitness and evolutionary generations.At last, a QoS-based web service selection verification system by using SNGSAA algorithm is designed and implemented. The running environment, general architecture, function modules and database of the system are introduced in detail. Then take the tourism service as an application example, the processes that users select the tourism services online are simulated.