Capability matchmaking of semantic web services with preconditions and effects

In order to solve the problem that the current matchmaking methods for semantic web service mainly focus on the matchmaking of IO （inputs, outputs） descriptions which may result in one-sidedness, a description-logic-based IOPE （inputs, outputs, preconditions, effects） description and matchmaking method is proposed for semantic web service. The description logic concept is used to annotate service IO and the description logic assertion is employed to describe service PE（preconditions, effects）. TBox subsumption checking is used to measure the subsumption relationship between IO descriptions of service request and advertising; ABox consistency checking is used for checking the logical implication between PE descriptions of service request and advertising. Based upon the logical implication, four kinds of PE matching degrees are proposed to measure and compare the pros and cons of the results of matchmaking. They are the exact, perfect, side-effect and common match. Experiments show that the method has a higher precision rate under the same recall rate compared with the existing method.

Pre-filtering based automatic composition of multi-QoS semantic web services

To support the rapid automatic services composition and fulfill multi-quality of service （multi- QoS） demand, we propose a novel approach to realize services composition automatically by a prefihering process. Aimed at a set of web services with similar functionality and different quality of service （QoS） , a semantic services chain is given and a corresponding constructing algorithm is proposed to construct the data structure. A pre-filtering process is put forward to find whether a composition service before planning exists. It can avoid aborted planning. An optimal planning algorithm is proposed which can choose the most suitable service from a lot of similar candidate services based on semantic service chains and multi-QoS values. The algorithms can improve the correctness and automation performances of automated semantic web services composition. As an example, a concrete composite process is analyzed. Experimental results show the validity of the composite process.

Semantic Web Services架构

近年来，随着电子商务的兴起和蓬勃发展，Web应用从局部化发展到全球化，从B2C（Busiliess—to—Customer）发展到B2B（Busincss—to—Busitiess），从集中式发展到分布式。Web服务作为一种新兴的Web应用模式，是一个崭新的分布式计算模型，是Web上数据和信息集成的有效机制。从电子商务应用领域来看，复杂的应用连接和程序代码造成了电子商务应用的高维护代价和更新代价，而Web服务正好能解决这一问题，成为目前应用环境中最为理想的解决方案。

Ontology在Semantic Web Services中的应用综述

介绍了Web Services的基本原理和Ontology的基本概念。基于这两种技术的结合,简单描述了多种基于本体的Web语言的发展,并重点阐述其中的OWL语言及其在Web Services中应用OWL-S的主要内容。最后介绍本体在语义web服务中的一些拓展性的应用。

Web services selection based on semantic similarity

Services discovery based on syntactic matching cannot adapt to the open and dynamic environment of the web. To select the proper one from the web services candidate set provided by syntactic matching, a service selection method based on semantic similarity is proposed. First, this method defines a web services ontology including QoS and context as semantic supporting, which also provides a set of terms to describe the interfaces of web services. Secondly, the similarity degree of two web services is evaluated by computing the semantic distances of those terms used to describe interfaces. Compared with existing methods, interfaces of web services can be interpreted under ontology, because it provides a formal and semantic specification of conceptualization. Meanwhile, efficiency and accuracy of services selection are improved.

Supporting web services reuse by semantic service component and composition pattern

Due to the fact that the existing web service description methods cannot address the issue of service reuse of various levels of granularity, the concept of service component is introduced, which packages together web services and choreography, and their operations and properties are presented in a consistent and uniform manner. Service components are published externally as normal web services and can thus be employed by webbased applications. In order to improve reusability and testability of service components, the concept of composition pattern is also proposed, which presents the relationships among service components. The relationships and relationship compositions have a rigorous semantic, so that composite components can be validated at the configuration stage. The composition patterns support to integrate service components of various levels of granularity. Experience indicates that the application assembly can effectively be conducted by understanding, selecting, and reusing components easily.

Efficient Composition of Semantic Web Services with End-to-End QoS Optimization

The efficiency of QoS-aware service composition is important since most service composition problems are known to be NP-hard. With the growing number of web services, service composition is like a decision problem on selecting services or/and execution plans to satisfy the users＇ end-to-end QoS requirements （e.g. response time, throughput）. Composite services with the same functionality may have dif-ferent execution plans, which may cause different end-to-end QoS. This paper presents a model combining semantic data-links and QoS, which leads to an efficient approach to automatic construction of a composite service with optimal end-to-end QoS. The approach is based on a greedy algorithm to select both services and execution plans for composite services. Empirical and theoretical analyses of the approach show that its time complexity is O（mn2） for a repository with n services and an ontology with m concepts. Moreover, the approach increases linearly in time when using an index to search services in the repository. Tests with a repository with 20 000 services and an ontology with 300 000 concepts show that the algorithm significantly outperforms current existing algorithms in terms of composition efficiency while achieving optimal end-to-end QoS.

An automatic subdigraph renovation plan for failure recovery of composite semantic Web services

A Web service-based system never fulfills a user＇s goal unless a failure recovery approach exists. It is inevitable that several Web services may either perish or fail before or during transactions. The completion of a composite process relies on the smooth execution of all constituent Web services. A mediator acts as an intermediary between providers and consumers to monitor the execution of these services. If a service fails, the mediator has to recover the whole composite process or else jeopardize achieving the intended goals. The atomic replacement of a perished Web service usually does not apply because the process of locating a matched Web service is unreliable. Even the system cannot depend on the replacement of the dead service with a com- posite service. In this paper, we propose an automatic renova- tion plan for failure recovery of composite semantic services based on an approach of subdigraph replacement. A replacement subdigraph is posed in lieu of an original subdigraph, which includes the failed service. The replacement is done in two separate phases, ofltine and online, to make the recovery faster. The ofitine phase foresees all possible subdigraphs, pre-calculates them, and ranks several possible replacements. The online phase compensates the unwanted effects and executes the replacement subdigraph in lieu of the original subdigraph. We have evaluated our approach during an experiment and have found that we could recover more than half of the simulated failures. These achievements show a significant improvement compared to current approaches

A semantic web services discovery approach based on a mobile agent using metadata

Purpose-The success of web services involved the adoption of this technology by different service providers through the web,which increased the number of web services,as a result making their discovery a tedious task.The UDDI standard has been proposed for web service publication and discovery.However,it lacks sufficient semantic description in the content of web services,which makes it difficult to find and compose suitable web services during the analysis,search,and matching processes.In addition,few works on semantic web services discovery take into account the user’s profile.The purpose of this paper is to optimize the web services discovery by reducing the search space and increasing the number of relevant services.Design/methodology/approach-The authors propose a new approach for the semantic web services discovery based on the mobile agent,user profile and metadata catalog.In the approach,each user can be described by a profile which is represented in two dimensions:personal dimension and preferences dimension.The description of web service is based on two levels:metadata catalog and WSDL.Findings-First,the semantic web services discovery reduces the number of relevant services through the application of matching algorithm“semantic match”.The result of this first matching restricts the search space at the level of UDDI registry,which allows the users to have good results for the“functional match”.Second,the use of mobile agents as a communication entity reduces the traffic on the network and the quantity of exchanged information.Finally,the integration of user profile in the service discovery process facilitates the expression of the user needs and makes intelligible the selected service.Originality/value-To the best knowledge of the authors,this is the first attempt at implementing the mobile agent technology with the semantic web service technology.

基于Web Services的服务合成技术研究综述

从分布式发展的角度分析了基于Web服务的新一代分布式计算范式特征以及生命周期模型,指出了Web服务合成的概念、特点和目标。对服务合成的方式与分类以及Web服务合成逻辑与结构类型进行了分析,同时将常用的Web服务合成方式划分为4种策略,即:基于系统架构(framework)的静态合成策略;基于工作流(workflow)的动态合成策略;基于语义网络(semantic web)的自动服务匹配与合成策略以及基于软件体系结构生命周期的综合式服务合成策略。在此基础上,对目前Web服务合成技术的主要研究领域与发展趋势以及服务合成过程中存在的主要问题与挑战进行了分析与综述。

基于目标距离评估的启发式Web Services组合算法

随着可用WebServices数量的快速增长,如何根据用户的需求来自动组合WebServices,生成满足用户需求的组合业务,成为一项亟待解决的课题.提出了一种基于用户需求目标距离评估的启发式算法,通过该算法,动态调用WebServices来自动生成满足用户所需目标的WebService组合,同时,该算法还能够根据WebServices组合经验,对以后的WebServices组合方案进行调整.实验结果表明:该算法能够很好地适应网络上WebServices的不稳定情况,与同类算法进行性能比较,也显示出基于目标距离评估的算法具有较好的性能.

Semantic Web研究综述

近年来 ,SemanticWeb逐渐成为WWW领域的研究热点以及智能化网络服务和应用开发中的关键技术之一。归纳了Se manticWeb技术的研究背景和主要发展历史。在分析了典型的SemanticWeb概念后 ,给出了SemanticWeb的定义。通过讨论SemanticWeb构想的层次框架模型 ,指出了各个层次扮演的角色 ,并着重分析了SemanticWeb的重要研究领域 ,指出了它们在SemanticWeb构架中的核心作用。通过分析SemanticWeb的应用领域和相关开发工具以及面临的问题和挑战 ,指明了SemanticWeb研究和实践的方向。作为总结 ,给出了SemanticWeb领域下一步的研究趋势。

Task-oriented web service discovery algorithm using semantic similarity for adaptive service composition

In order to achieve adaptive and efficient service composition, a task-oriented algorithm for discovering services is proposed. The traditional process of service composition is divided into semantic discovery and functional matching and makes tasks be operation objects. Semantic similarity is used to discover services matching a specific task and then generate a corresponding task-oriented web service composition （TWC） graph. Moreover, an algorithm for the new service is designed to update the TWC. The approach is applied to the composition model, in which the TWC is searched to obtain an optimal path and the final service composition is output. Also, the model can implement realtime updating with changing environments. Experimental results demonstrate the feasibility and effectiveness of the algorithm and indicate that the maximum searching radius can be set to 2 to achieve an equilibrium point of quality and quantity.

Reducing semantic bias of annotations for semantic web service discovery

In order to improve the effectiveness of semantic web service discovery, the semantic bias between an interface parameter and an annotation is reduced by extracting semantic restrictions for the annotation from the description context and generating refined semantic annotations, and then the semantics of the web service is refined. These restrictions are dynamically extracted from the parsing tree of the description text, with the guide of the restriction template extracted from the ontology definition. New semantic annotations are then generated by combining the original concept with the restrictions and represented via refined concept expressions. In addition, a novel semantic similarity measure for refined concept expressions is proposed for semantic web service discovery. Experimental results show that the matchmaker based on this method can improve the average precision of discovery and exhibit low computational complexity. Reducing the semantic bias by utilizing restriction information of annotations can refine the semantics of the web service and improve the discovery effectiveness.

基于Web Services的语义异构数据集成设计与实现

高校在信息化建设过程中积累了大量异构、异质的数据源,如何将这些异构数据源中相关的数据资源进行有效整合是当前急需解决的问题。为此,提出了一种新的基于Web Services的异构数据集成解决方案,利用Web Services技术在异构数据集成中的优势,采用虚拟数据库法设计思想,通过设计领域字典表及字段映射表,有效地解决了异构数据集成中最难解决的语义异构问题,并从数据模型转换、全局查询等方面阐述了该方案的可行性。实验结果表明,该方案具有可用性和高效性。

语义Web Services描述框架的比较研究

由于Web Services可处于分布式环境中、在异构平台上进行交互以及高度的集成性等优点,Web Services技术引起了越来越多的人的关注,而语义Web Services一直是该领域的研究热点。文章首先通过一个例子说明语义Web Services产生的必要性,然后主要介绍了目前Web Services领域的OWL-S、WSMO、SAWSDL和FLOWS四种服务描述框架,并对其进行比较分析。

Efficient semantic web service matching using common ontology

To solve the bottleneck problem in centralized service discovery methods,a novel architecture based on domain ontology for semantic service discovery is proposed.This distributed architecture can adjust the domain partition and allocate system resources automatically.The characteristics of this mechanism are analyzed,including scalability,self-organization and adaptability.In this mechanism,semantic web service discovery is separated into two parts.First,under balance tree topology,registry proxy can rapidly forward requests to the objective registry center,and avoid the bottleneck problem.Secondly,a semantic distance based service matching algorithm is proposed to promote the effect of service searching.The results of simulation experiments show that the proposed mechanism can serve as a scalable solution for semantic web service publication and discovery.And the improved matching algorithm has higher recall and precision than other algorithms.

基于语义的GIS Web Services

WebServices是一个全新的架构,是在中间件技术之后的又一个分布式计算的飞跃.而WebServices对于GIS系统软件的意义也非常重大.把WebService技术引入GIS领域,可以非常理想地解决困扰GIS应用领域多年的异质空间数据互操作的问题.针对GIS应用的特殊要求,基于语义的WebServices是一个非常好的选择.它可以通过Web方式获取分布的空间数据并完成GIS系统之间的交互.该文在苏州市土地局和苏州市科技局合作的地理信息互操作项目研究基础上,提出语义GISWebServices的概念,并在此基础上给出一个可以实现的概念模型以解决实际的应用问题.

基于Web Services/Ontology的异构系统集成框架

Web Services是一种面向服务的体系结构,其突出优点是实现了真正意义上的平台独立性和语言独立性。Ontology是集成各种异构系统时语义统一的有效方案。本文在分析了Web Services/Ontology的体系结构和关键技术后,提出了一个基于Web Services的Ontology集成框架,并对框架的工作原理进行了研究。该框架可以有效地用于处理复杂环境下各种异构系统的集成。