"语义万维网服务(SWSI)"- –

“语义万维网服务” Semantic Web Services Initiative (SWSI) 的目标是使目前的万维网技术结合相关的最新进展,得以发挥其最大潜能。

语义万维网技术

万维网协会主席 Tim Berners-Lee 认为万维网的未来是”语义万维网”–万维网向机读信息和自动服务的延伸而远远超出目前的能力。在数据、程序、网页以及其他万维网资源之上的语义呈现,将使万维网成为基于知识的万维网,使目前的服务提升到一个新的水平。通过”理解”万维网上的内容,达到更精确的过滤、分类以及检索信息资源,自动服务将在更大的范围上帮助人类实现目标。这个过程将最终实现极端丰富的知识系统以及在此基础上的特别的推理服务。这些服务将有助于我们日常生活的方方面面,像今天人们对于电力一样普遍而不可或缺。

目前的万维网只是信息的堆积而不提供信息的处理,也就是说并没有把计算机当作一种计算设备。最近围绕 UDDI, WSDL, 和 SOAP 等发展起来的新技术正在把 Web 变成一种新的水平层次上的服务。应用软件课题通过万维网而获得和执行,这个技术叫做 Web 服务。 Web 服务通过提供一种程序自动交流、发现服务的机制,从而可以大大提高万维网体系结构的潜能。因而得到众多软件开发公司的关注。 Web 服务使电脑设备连接在一起,以一种新的方式使用因特网交换和联合数据。 Web 服务技术的关键在于使用松散耦合的”随时”组合可重用软件组件的方式提供服务。这从技术和业务两方面都产生深远的影响。

Semantic Web Service 似乎又多了一个兄弟: Semantic Web enabled Web Services ,欧洲 IST 的一个项目。

相关的项目、组织或网站:

http://swws.semanticweb.org/

http://swsi.semanticweb.org/

Software can be delivered and paid for as fluid streams of services as opposed to packaged products. It is possible to achieve automatic, ad hoc interoperability between systems to accomplish organizational tasks. Examples include business application, such as automated procurement and supply chain management, but also non-commercial applications as well as military applications. Web services can be completely decentralized and distributed over the Internet and accessed by a wide variety of communications devices. Organizations can be released from the burden of complex, slow and expensive software integration and focus instead on the value of their offerings and mission critical tasks. The dynamic enterprise and dynamic value chains would become achievable and may be even mandatory for competitive advantage.


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关于OWL-S的服务描述- –

    服务发现是否假设请求者和提供者使用同一本体?肯定不是。否则 OWL-S 的使用会大大受限,甚至失去意义了,因为其目的本来就是为了寻找合适的本体,其前提假设就有问题。(但是是否假设使用同一本体编码语言呢?也不应该是,但是不一定)

      会对本体中介进行一些规范吗?就像 WSMO 对面向对象的中间件一样?虽然可以这样做,但是至今还没有这方面的研究计划和进展。 OWL-S 是采用 OWL 语言的一种服务描述语言,并不规定是否一定有中间件或者服务实现某些功能。

        是否仅包含输入描述和输出描述?答案也是否定的。 OWL-S 纲要是用于”广告”语义 Web 服务的,描述的内容包括服务描述、产品描述、输入、输出、前提条件、效果、存取条件、服务质量、安全参数等等,凡是与服务有关的参数均可以用 OWL-S 进行描述。

        来自于Katia Sycara” < katia+@cs.cmu.edu >的一帖关于owl-s服务描述问题的澄清,感到有必要存档一下。

        There were a number of issues raised in this discussion:

        1. Does OWL-S discovery assumes that requesters and provides use a unique ontology?

        The answer is NO. OWL-S does not assume the use of a single onrology. It is difficult, however, to see what you mean by “one single ontology”. If you mean “one single OWL file”, then of course trivially OWL-S does not assume a single ontology since you can import as many OWL files as you desire in an OWL-S description, and use any of the concepts defined in those files to describe the OWL-S profile or any other OWL-S component. During the discovery process the Profile of the requested service may refer to a concept, say a:A (the concept A defined in “file” a), and an advertisement may refer to concept b:B that belong to a different ontology (different owl files), and yet b:B may be defined as a subclass of a:A. In this case, matching engines would still be able to match exploiting the logical relation between A and B. At CMU, we have shown different kinds of matches (e.g. exact, plug-in etc) in our matching algorithm (see e.g. [3]).

        Another way in which the use of different ontologies can be handled in OWL-S is through mapping rules that could be expressed in SWRL. In this way, to the extent that the similarity between A and B can be made explicit, then the mapping can be exploited. Of course there are issues of where these mappings live, how it is discovered where they live, since of course in the process of service discovery one does not know a priori what the ontological needs of one request would be vis a vis the current advertisement knowledge base. Even if one assumes a unique knowledge base containing such mappings, another set of issues is of course, how this knowledge base gets searched efficiently. 我的论文的一部分就是要解决这个问题:采用登记服务自动完成映射工作,但是基于怎样的请求?机制仍然成问题。

        The issue of ontological mapping is an old and well known one that has predated Semantic Web Services. Work on how to express mappings to achieve semantic interoperability efficiently (even assuming the mapping rules are known) has been going on since the late 80&apos;s (perhaps even earlier).

        The general problem of arbitrary ontology mapping is an open research problem. The real scientific work is in trying to attack the technical issues that I outlined (and others that are there but I did not refer to). After we solve these scientific problems (ie. How to derive the mappings, and how to use them), we can worry about what to call the algorithms.

        Since ONTOLOGY MEDIATION is an open research issue, OWL-S is agnostic about the actual ontology mediation process used.( 这方面应该有研究论文,也可以参考一下,属于论文中创新性的内容 ) To the extent that the mediation process is a service, rather than a set of rules, it can be represented in OWL-S and discovered.

        2. Should OWL-S do something about ontological mediation like WSMO is doing with the OO mediators?

        Up to now, there is no clear operational definition of what a WSMO mediator is, neither is there a clear specification of an ontology or language for describing mediators, or an algorithm for ontological mediation.

        To the extent that WSMO mediators are services, rather than sets of rules, they can be represented in OWL-S by specifying what is their profile, process model and grounding (for a detailed discussion on this point see [2]). Furthermore, the discovery mechanism may then become similar to a composition procedure where you combine discovery of the appropriate mediator with the discovery of the appropriate service.

        Note that if you take this viewpoint, the sentence “OWL-S has no mediators” is non-sensical: it is analogous to sentences like “Java has no Operating System” or other such sentences. OWL-S is a language (it uses OWL semantics) that allows you to describe Web services, it does not tell you what infrastructure Web services need, nor does it stipulate the existence of mediators or of a discovery registry or any other component. If you think you need a mediator, the role of OWL-S is to provide you the tools to describe a mediator if you decide to implement it as a Web service. If you look at [2] there is a discussion on how to do that.