Meta web service: building web-based open decision support system based on web services

Web services are currently one of the trends in network-based business services, which intuitively will be applied to build a semantic web-based decision support system (DSS). Since web services are self-contained, modular business process applications, based on open standards, enable integration models for facilitating program-to-program interactions. Decision modules in a semantic web-based DSS can be viewed as a web service. However, according to the current features, web services know only about themselves, they are neither autonomous, nor are they designed to use ontologies; they are passive until invoked, and they do not provide for composing functionalities. These lead to the motivation on building a sophisticated web service to contain these features and to utilize web services on behalf of the user. This paper aims to propose a new concept of Meta Web Service, a web service-based DSS. The meta web service understands the user's problem statement with ontology, performs web service discovery, web service composition, and automatically generates codes for composite web service execution. Case-based reasoning is applied to quickly find past histories of successful service compositions. A prototype of research web service has been developed to show the feasibility of the proposed idea.     

Composing semantic Web services under constraints

Web service composition is an inevitable aspect of Web services technology, which solves complex problems by combining available basic services and ordering them to best suit the problem requirements. Automatic composition gives us flexibility of selecting best candidate services at composition time satisfying QoS requirements; this would require the user to define constraints for selecting and composing candidate Web services. In this work, a Web service composition approach is presented in which a rich set of constraints can be defined on the composite service. The output of the framework is the schedule of Web service composition in which how and when services are executed is defined. The basic properties of the proposed approach is converting Web service composition problem into a constraint satisfaction problem in order to find the best solution that meets all criteria defined by user and providing semantic compatibility and composability during composition.     

基于多本体的语义Web服务发现研究

随着大量Web服务的出现,迫切需要高效的服务发现方法。语义Web服务将Web服务和语义相结合,充分利用语义增强Web服务。现有的语义Web服务发现研究中,大多采用同一本体描述服务需求方和提供方的知识。而现实世界里,很多时候服务需求方和服务提供方采用了不同的本体。针对多本体下的语义Web服务发现问题,给出了一种新的计算不同本体概念相似性的算法,提出了基于多本体的语义Web服务发现方法。实验结果表明了该方法的有效性。     

基于本体和QoS的Web服务组合

服务组合是一种重要的服务应用形式,为服务重用与自动化集成提供了支撑。传统服务组合方法依赖基于关键字的查找,缺乏服务语义的分析,且现有服务组合算法往往未考虑QoS的因素。文章将语义本体和QoS结合起来,共同作为Web服务选择和组合的条件,以提高服务组合的质量和组合结果的执行效率。仿真实验结果显示出该方法较传统组合方法能够获得更好的组合结果,使应用的服务性能得到改善。     

Semantic web service composition testbed

A huge amount of web services are deployed on the Web, nowadays. These services can be used to fulfill online requests. Requests are getting more and more complicated over time. So, there exists a lot of frequent request that cannot be fulfilled using just one web service. For using web services, composing individual services to create the added-value composite web service to fulfill the user request is necessary in most cases. Web services can be composed manually but it is a too tedious and time consuming task. The ability of automatic web service composition to create a new composite web service is one of the key enabling features for the future for the semantic web. There are some successful methods for automatic web service composition, but the lack of standard, open, and lightweight test environment makes the comparison and evaluation of these composition methods impossible. In this paper we propose an architecture for a light weight and scalable testbed to execute, test and evaluate automatic web service composition algorithms. The architecture provides mandatory components for implementing and evaluation of automatic web service composition algorithms. Also, this architecture provides some extension mechanisms to extend its default functionalities. We have also given reference implementations for web service matchmaking and composition. Also, some scenarios for testing and evaluating the testbed are given. We have found that the performance of the composition method will dramatically decrease as the number of web services increases.     

本体驱动的语义Web服务动态复合的研究

传统Web服务的复合由于缺乏足够的语义信息而大大降低了服务复合的效率和准确率。语义Web弥补了传统Web语义不足的缺点。但是,面对语义Web上分布的海量知识,如何有效地利用语义信息实现Web服务复合成为一个迫切需要解决的问题。文章针对这一问题,提出一种基于多维用户模型的动态服务复合机制。该机制在Web服务语义标识的启发下通过语义匹配算法能够实现Web服务的顺序复合和并行复合。采用这种服务复合机制将会在一定程度上提高语义Web服务复合的效率和准确率。     

基于SWRL的网络管理信息定义

针对当前现有的网络与系统管理信息定义语言种类多、语义和规则描述能力弱的缺陷,提出了一种在基于本体的网络管理框架中使用语义网规则语言SWRL(SemanticWebRuleLanguage)定义网络管理信息的方法。通过本体语言从语义的层面整合现有的管理信息定义语言,使用RuleML(RuleMarkupLanguage)定义管理行为的规则,提高了网络管理信息定义的表达力,为智能网管奠定了基础。     

Magpie: Experiences in supporting Semantic Web browsing

Magpie has been one of the first truly effective approaches to bringing semantics into the web browsing experience. The key innovation brought by Magpie was the replacement of a manual annotation process by an automatically associated ontology-based semantic layer over web resources, which ensured added value at no cost for the user. Magpie also differs from older open hypermedia systems: its associations between entities in a web page and semantic concepts from an ontology enable link typing and subsequent interpretation of the resource. The semantic layer in Magpie also facilitates locating semantic services and making them available to the user, so that they can be manually activated by a user or opportunistically triggered when appropriate patterns are encountered during browsing. In this paper we track the evolution of Magpie as a technology for developing open and flexible Semantic Web applications. Magpie emerged from our research into user-accessible Semantic Web, and we use this viewpoint to assess the role of tools like Magpie in making semantic content useful for ordinary users. We see such tools as crucial in bootstrapping the Semantic Web through the automation of the knowledge generation process.     

Service Composition and Execution Plan Generation of Composite Semantic WEB Services Using Abductive Event Calculus

Web Service composition is indispensable, as a single web service cannot satisfy the complex functional requirement of a user. The two key challenges of semantic web service composition are the discovery of the most relevant atomic services from the composite semantic web services and by no means we can assure the execution of the composed atomic services in a proper order. In this work, these two challenges are addressed, and a novel architecture is proposed for atomic service discovery, composition and automatic plan generation for the proper execution of its candidate services. The proposed architecture takes the advantage of abductive event calculus that uses abductive theorem prover to generate a plan for the proper order of execution of the atomic services. The research has found that the plan generated by the proposed architecture is sound and complete.     

Frame Logic-based specification and discovery of semantic web services with application to medical appointments

Matching web services and client requirements in the form of goals is a significant challenge in the discovery of semantic web services. The most common but unsatisfactory approach to matching is set-based, where both the client and web services declare what objects they require and what objects they can provide. Matching then becomes the simple task of comparing sets of objects. This approach is inadequate because it says nothing about the functionality required by the client or the functionality provided by the web service. As an alternative, we use the Frame Logic as implemented in Flora-2 to specify web service capabilities and client requirements, including their preconditions, postconditions, and ontologies, implement a logic-based discovery agent using Flora-2, demonstrate its usefulness in a medical appointment making scenario, and show its efficiency both theoretically and by benchmarking. The result is an expressive yet concise representation scheme for semantic web services, and a practical, efficient, powerful, and fully implemented matching engine based purely on logical inference for web service discovery, with direct applicability to Web Service Modeling Ontology and Web Service Modeling Language, because both are based on Frame Logic.     

Synthy: A system for end to end composition of web services

The demand for quickly delivering new applications is increasingly becoming a business imperative today. However, application development is often done in an ad hoc manner resulting in poor reuse of software assets and longer time-to-delivery. Web services have received much interest due to their potential in facilitating seamless business-to-business or enterprise application integration. A web service composition system can help automate the process, from specifying business process functionalities, to developing executable workflows that capture non-functional (e.g. Quality of Service (QoS)) requirements, to deploying them on a runtime infrastructure. Intuitively, web services can be viewed as software components and the process of web service composition similar to software synthesis. In addition, service composition needs to address the build-time and runtime issues of the integrated application, thereby making it a more challenging and practical problem than software synthesis. However, current solutions based on business web services (using WSDL, BPEL, SOAP, etc.) or semantic web services (using ontologies, goal-directed reasoning, etc.) are both piecemeal and insufficient. We formulate the web service composition problem and describe the first integrated system for composing web services end to end, i.e., from specification to deployment. The proposed solution is based on a novel two-staged composition approach that addresses the information modeling aspects of web services, provides support for contextual information while composing services, employs efficient decoupling of functional and non-functional requirements, and leads to improved scalability and failure handling. We also present Synthy, a prototype of the service composition system, and demonstrate its effectiveness with the help of an application scenario from the telecom domain.     

Joint semantic similarity assessment with raw corpus and structured ontology for semantic-oriented service discovery

Semantic-oriented service matching is one of the challenges in automatic Web service discovery. Service users may search for Web services using keywords and receive the matching services in terms of their functional profiles. A number of approaches to computing the semantic similarity between words have been developed to enhance the precision of matchmaking, which can be classified into ontology-based and corpus-based approaches. The ontology-based approaches commonly use the differentiated concept information provided by a large ontology for measuring lexical similarity with word sense disambiguation. Nevertheless, most of the ontologies are domain-special and limited to lexical coverage, which have a limited applicability. On the other hand, corpus-based approaches rely on the distributional statistics of context to represent per word as a vector and measure the distance of word vectors. However, the polysemous problem may lead to a low computational accuracy. In this paper, in order to augment the semantic information content in word vectors, we propose a multiple semantic fusion (MSF) model to generate sense-specific vector per word. In this model, various semantic properties of the general-purpose ontology WordNet are integrated to fine-tune the distributed word representations learned from corpus, in terms of vector combination strategies. The retrofitted word vectors are modeled as semantic vectors for estimating semantic similarity. The MSF model-based similarity measure is validated against other similarity measures on multiple benchmark datasets. Experimental results of word similarity evaluation indicate that our computational method can obtain higher correlation coefficient with human judgment in most cases. Moreover, the proposed similarity measure is demonstrated to improve the performance of Web service matchmaking based on a single semantic resource. Accordingly, our findings provide a new method and perspective to understand and represent lexical semantics.     

扩展UDDI以支持语义信息的研究

介绍了一种扩展UDDI以支持语义信息的方法,即在注册Web服务时添加语义信息,并支持基于语义的查询。首先在UDDI系统中加入一个领域本体库,再为该UDDI中的每个注册服务添加语义信息,并将服务和本体库的对应关系存入到UDDI的数据库中。在服务申请者查询Web服务时,由用户提供语义查询模板,根据用户描述的本体语义信息得到候选服务列表,再根据用户对服务质量的要求计算候选服务的匹配度,将候选服务依照其匹配度的大小顺序返回给用户。     

语义网服务中的本体综述

作为实现下一代Web的集成方案,语义网服务将语义Web技术和Web服务技术相结合,以支持Web服务的自动发现、选择、合成和执行.本体是语义网服务的理论基础.介绍了Web资源描述本体OWL和Web服务描述本体的概况,并对3种主流的Web服务语义描述框架进行对比分析,为语义网服务中本体的创建提供基础知识.研究了语义网服务中存在的各层次的本体异构问题,明确了语义网服务中本体集成的主要研究方向.     

基于本体集成的语义标注模型设计

语义Web的全面实现需借助于语义标注,标注网页信息会涉及到多个本体.据此,通过研究桥本体,提出一个在本体集成的基础上建立起来的多本体语义标注模型.该模型利用桥本体集成顶层本体和多个领域本体,同时借助基于本体的信息抽取技术对网页进行语义标注,并将标注信息存入标注库,使标注信息与网页分离,提高语义检索的效率.通过举例说明了本模型的合理性.