在Web技术迅速发展的今天，Web服务作为一种分布式应用技术正在引起越来越广泛的重视。随着用户对服务集成度和服务性能要求的不断提高，工业界和学术界关注的热点正在由单一的Web服务向组合的Web服务过渡。而语义是解决Web服务组合问题的重要使能技术。本文涉及工作正是顺应这一趋势，展开对基于语义的Web服务组合相关问题的研究。在对Web服务组合相关技术和研究现状进行深入调研的基础上，借鉴现有Web服务标准，对其在语义等方面进行完善和扩充，并应用于Web服务组合生命周期的各个环节，形成一个完整、可实现性强、适应度高和易于扩展的服务组合框架，并在此基础上对服务描述的语义标注和服务匹配选择算法展开深入的探讨。在服务组合框架的研究中，对框架结构进行层次化的模块划分，明确了各个模块的功能和协作方式，并给出了涵盖各种类型语义的实现方案。在服务描述环节选择本体概念匹配及语义标注的方法，设计了基于XML的QoS描述；在服务请求环节采用参照服务过程描语言的结构进行语义添加并形成服务过程请求模版的方式；在服务发布环节中确定了适用的添加语义信息的方式；在服务发现及匹配环节中设计了服务匹配和选择算法；并在以上各环节的基础上形成满足要求的服务过程。在框架两个重点环节的方法研究中，服务描述的语义标注环节采用在服务描述与本体间建立映射的方法评价两者的匹配程度，选择合适的本体概念作为语义扩展。通过实验，考查了算法的性能和适用领域，并对结果进行了分析。在服务匹配及选择环节的模型和算法设计中，对语义服务进行了形式化表达，探讨了模版匹配和承接度匹配的计算方法，提出了一种与服务组合特点相适应的、基于过程结构归约的服务选择算法，有效降低了服务过程整体匹配度评价以及在大量候选服务中进行选择的计算复杂度，并对上述各种表达方式和算法在语义层面上进行了一致化描述。

As rapidly as web technology is developing, web service as a distributed application technology is being more and more emphasized. As higher integration level and service performance is required, the attention of industry and academic research is transiting from individual web service to composite web services. Semantic is a key technology in solving service composition problems. Following such a trend, the research this thesis involves is about web service composition based on semantic. Based on a thorough investigation of web service composition related technology and research activities, this thesis refers to and semantically enhances current industry standards, and implemented them through the service composition lifecycle, forms an integrated, highly realistic, compatible, and extendable service composition framework, based on which in depth research on semantic annotation of service description and service matching and selection algorithms are carried on.The service composition framework is divided into modules at different levels. The function of each module and the relationship among modules are defined. The realization methods containing comprehensive semantics are proposed. Ontology concept matching and semantic annotation is used in service description. QoS description based on XML is designed. Service process template based on process description language is service request. Suitable semantic importing approach is used in service publication. Algorithms are desighned in service discovery and matching. Service process is generated based on the steps above.In the research on two key modules of the framework, service description and semantic annotation module implements a mapping approach among service description and ontology. Matching degrees are evaluated and ontology concepts are selected for semantic extension. Through experiment, the performance and application areas of the algorithm are evaluated and results are analyzed. During the design of models and algorithms in service matching and selection, formalized description of semantic service is defined, template matching and service compatibility degree algorithms are developed. A process structure based reduction algorithm is specifically designed for service selection, which effectively reduces the computing complexity for process overall matching degree and for selecting services among large amount of candidates.