【作者】 于守健；

【导师】 乐嘉锦；

【作者基本信息】 东华大学 ， 控制理论与控制工程， 2005， 博士

【摘要】 随着对Web服务的研究和应用的不断深入,越来越多的企业将自己的业务包装成Web服务发布。在基于Web服务的业务流程集成模型中,抽象业务流程逻辑的描述,与业务流程功能的实现分离开来,从而克服了传统工作流技术在实现业务流程集成方面的不足。但是,单个Web服务的功能有限,难以满足企业级应用的流程集成需要。Web服务组合能把相对简单的Web服务,按业务流程逻辑组合起来,从而提供更强大、更完整的业务功能。为了实现业务流程自动集成,本文提出了Web服务自动组合机制。当企业的业务流程发生改变时,通过自动、动态地组合己有的Web服务,不需要重新开发新的服务,从而能很好地适应现代企业业务环境的多变性和动态性。 Web服务自动组合的关键,是根据目的服务的描述,与服务注册中心中Web服务的描述信息进行匹配,从而发现满足需求的服务。因此本文分别从Web服务的行为描述和接口描述两方面,研究了Web服务自动组合技术。目前使用的标准只是从语法层次对Web服务的接口进行描述,不能表达语义信息,容易造成服务查准率低,从而难以保证服务组合的质量和性能。本文试图通过扩展服务接口的语义描述,将Web服务接口的匹配从语法层次上升到语义层次,进一步研究基于语义的Web服务自动组合方法。此外,本文还针对集中式注册中心极易造成性能瓶颈、单点失败等缺陷,提出了分布式Web服务目录系统,从而支持非集中式的服务发布与发现。具体来讲,本文做了以下四个方面的工作: (1) 研究了基于行为的Web服务组合方法。首先分析了业务流程中活动之间交互行为,然后以有限状态自动机模型,形式化定义了业务流程的内模式和外模式。在此基础上,提出了组合服务存在性的判定依据,并给出了组合服务的计算方法。 (2) 研究了基于接口匹配的Web服务自动组合方法。首先分析了Web服务组合的类型和消息依赖关系,然后以当前标准—WSDL(Web ServicesDescription Language,简称WSDL),作为服务接口的描述语言,提出了服务更多还原

【Abstract】 With further research and application of Web service, more and more enterprises prefer to package their business as Web services. In the model of business process integration based on Web service, description of abstract business process is separated from its concrete implementation. This feature overcomes the deficiency of traditional workflow technique in business process integration. But the function of single Web service is limited, which cannot fulfill the requirement of process integration at enterprise level. Web service composition can combine multiple simple services together according to business process logic, and therefore it can provide complex and comprehensive business functionality. Moreover, when the business process is changed, automatic and dynamic Web service composition can successfully adapt to the more changeful and dynamic business environment, and new services need not to be rebuilt.Automatic Web service composition relies on the matching of target service description with existing descriptions in the UDDI registry, which will discover the appropriate service. Thus this paper studies automatic Web service composition technology both from behavior description and interface description of Web service. The current standard can only provide syntactic Web service description, and cannot express semantic information. This will decrease the precision of Web service discovery, which cannot guarantee the performance and quality of Web service composition. Therefore we try to upgrade interface matching from syntactic level to semantic level by incorporating semantic into service interface description. Accordingly we have studied semantic Web service composition. Furthermore, in order to overcome the limitations of centralized UDDI registry such as performance bottlenecks and single point failure, we have proposed a kind of distributed Web service catalog system, which supports decentralized Web service publication and discovery. This paper has made research on the following four aspects:(1) Studied Web service composition method based on behavior description. First, analyzed the interaction behavior among activities in business process. Then formalized the inner schema and outer schema of business process based on finite state machine model. In the end, proposed methods for checking existence of composite service, and illustrated the algorithm for computing composite service.(2) Studied Web service composition method based on interface description. First, analyzed the types of Web service composition and message dependency. Then proposed Web service interface matching algorithm with the current standard—WSDL as the Web servicedescription language. In the end, evaluated the matching algorithm by experiments.(3) Studied Web service composition method by extending service interface semantic description. First, extended Service interface semantic description from three levels: message parameter, message and operation, and proposed a lightweight semantic Web service description model. Then proposed service interface semantic matching algorithm from these three levels. In the end, implemented an initial prototype, and illustrated the application of this composition method in business process integration by an example of textile enterprise.(4) Studied distributed Web service publication and discovery technology. First, analyzed the limitations of typical centralized UDDI registry. Then proposed the distributed Web service catalog system utilizing the efficient data location ability of distributed hash table, and discussed the procedure of Web service publication and discovery under this system, as well as the system evolution. In the end, made some improvements for the pure distributed service catalog system, and proposed a kind of hierarchical Web service catalog system according to the hierarchical organization of distributed hash table.更多还原