09Web服务实用技术语义Web服务.ppt

语义是事物的观察者给事物本身赋予的含义，一致共享的语义构成观察者对事物的知识，是观察者之间互相交流的基础。 语义网通过给万维网上的文档(如:HTML)添加能够被计算机理解的语义(Meta data)，从而使整个万维网中现存的信息发展成一个巨大的全球信息库、知识库。 Web 服务使用标准的、规范的 XML进行描述，包括消息格式、传输协议和位置，隐藏了实现服务的细节。 WSDL从句法层面对Web服务的功能进行描述，包括4个不同的方面：数据类型、消息、操作和访问端口。 这只是提供了Web服务的接口描述，对服务的行为约束和属性描述缺乏进一步的支持。 缺陷 数据管理有序性与Web上信息无序性； 有哪些信誉好的足球投注网站引擎查全查准要求与服务描述缺语义； 信息获取效率与Web海量动态数据。 语义Web服务的主要方法是利用Ontology来描述Web服务，通过带有语义信息的Web服务来实现服务的自动发现，调用和组合。 语义Web和Web 服务是语义Web服务的两大支撑技术。 OWL-S是连接两大技术的桥梁。 目前对语义Web服务标记语言研究最典型的组织就是DARPA（Defence Advanced Research Projects Agency）组织，其研究组OWL Services Coalition提出了语义Web服务标记语言OWL-S Web was “invented” by Tim Berners-Lee , a physicist working at CERN TBL’s original vision of the Web was much more ambitious than the reality of the existing (syntactic) Web: TBL (and others) have since been working towards realising this vision, which has become known as the Semantic Web E.g., article in May 2001 issue of Scientific American… The Semantic Web is an extension of the current web in which information is given well-defined meaning, better enabling computers and people to work in co-operation.  – Tim Berners-Lee, James Hendler, Ora Lassila, The Semantic Web, Scientific American, May 2001 本体(ontology) a philosophical discipline, branch of philosophy that deal with the nature and the organization of reality. Science of being ? Tries to answer the questions: what is being? what are the features common to all beings? Ontology is a formal, explicit specification of a shared conceptualization – Gruber 要点： Conceptualization: an abstract model of phenomena in the world by having identified the relevant concepts of those phenomena. Explicit: the type of concepts used, and the constraints on their use are explicitly defined. Formal: the fact that the ontology should be machine readable. Shared: ontology should capture consensual knowledge accepted by the communities ? What is a concept?? Different communities have different notions on what a concept means:? formal concepts? concept