信息提供类Web服务基于查询重写的自动组合方法

现有对Web服务自动组合的研究很少考虑信息提供类服务不同于一般服务的特点.文中提出一个简单,但具有明确语义的信息提供类服务功能模型,表达了该类服务不改变世界状态,有些输入输出参数不具有语义类型的特点;然后提出并实现了一个相应的自动组合方法.该方法以数据集成领域中一种查询重写算法MiniCon为基础,充分利用了前述特点,支持最基本的语义推理,能自动生成可直接运行的BPEL脚本.其性能特点与传统的基于搜索过程的方法具有互补性.在一类典型问题上进行的性能测试表明该方法具有相当强的实用价值.     

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.     

基于agent的Web服务集成原型系统的模型研究

现行Internet平台下的Web服务集成技术一般是以基于XML的工作流描述语言和工作流技术为基础,其执行引擎是采用集中式,使得执行引擎点成为Web服务组合的瓶颈;提出一种基于agent技术的Web服务集成原型系统ABWSC(Agent Based Web Serv- ices Composition),该系统使用一个多agent系统作为Web服务集成系统的执行引擎,使得Web服务集成系统的执行方式由集中式转为分布式;通过模型的模拟实现证明该模型使得Web服务之间的协同方式由单一性转变到灵活多样性,令Web服务具有了一定的自主性和自适应性,更能适应多变的网络环境。     

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.     

基于WSFL的Web服务组合

运用Web服务组合技术可以将越来越多的Web服务组合成一个更新更强大的服务.随着Web服务组合技术的发展,出现了各种用于描述和规范Web服务组合过程的语言.其中,WSFL是一种相对成熟的Web服务组合语言.介绍了Web服务组合的概念、方式、过程以及WSFL的相关概念,提出了使用WSFL在多个服务提供者之间进行商业过程的模型.     

基于语义P2P的UDDI组合服务发现模型

随着Web服务数目的增长和对实时性需求的增加,单一集中式的UDDI服务注册中心难以满足实际需求,而基于某个领域的UDDI虽然查找迅速却难以满足所有用户的要求,于是如何组织一个逻辑上完整的服务注册中为Web服务应用的一个新研究方向.基于P2P的底部架构,将服务注册中心作为P2P网络内基本节点,提出了一个根据本体信息对服务注册节点进行语义分类查找的Web服务发现模型.在模型的基础上,提出了在P2P层支持语义的一种发现的方法.提出的Web服务发现模型既结合了集中式Web服务发现方式和分布式Web服务方式发现的优点,又创新性地在P2P发现方面加入了本体信息.     

基于带权图规划算法的语义Web服务组合

随着Internet技术的发展,一个单独Web服务的功能并不完备,为了实现复杂、强大的Web服务的功能,就需要把多个Web服务组合起来实现复杂的功能。文中提出了一种基于带权图规划的语义Web组合算法,该方法引入人工智能中规划图的思想,利用图规划的前向扩张思想,能快速在分布的、异构的Web服务中自动地找到满足条件的服务组合;同时,通过领域本体以及OWL—S的服务描述,来计算Web服务匹配的相似度,利用图规划解抽取阶段思想,抽取权值最小的服务序列,提高了服务组合的正确率和查全率。     

基于扩展语义接口的Web服务动态组合方法

自动地根据用户请求进行服务的动态组合是目前Web服务领域的关键问题.针对该问题,提出了一种基于本体的服 务动态组合方法,设计并实现了一个服务动态组合原型.首先Web服务按照一定规则被抽象为本体模型,然后通过分析所 构造服务的模型来实现服务的匹配,最后利用BPEL4ws对匹配生成的服务组合序列来进行自动的组合.实验结果表明,该 方法细化了服务接口的语义,并且在发现结果上有更高的准确性.     

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.     

基于服务组合的GIS应用模型集成方法研究

针对当前GIS应用模型集成过程中存在的数据和功能冗余、模型难以复用等问题,指出基于Web服务组合技术在GIS应用模型集成中的优势,提出了一种GIS应用模型驱动的服务组合方法,并详细阐述了模型分解、服务组合流程、服务选取及实现技术等,为扩展GIS的应用功能提供了一种可行的解决方案。最后,以震害应急指挥过程为例表明了该方法能有效提高模型集成的灵活性和复用性,有较高的应用价值。     

基于邻接矩阵的Web服务组合

针对当前Web服务组合方法在动态性和算法时间复杂度方面存在的不足,提出一种基于邻接矩阵的服务组合方法,使用邻接矩阵表示服务间的顺序及并发关系,在构建抽象服务基础上由领域专家初步建立抽象服务的组合关系,利用Warshall算法计算传递闭包来判定服务请求是否可满足,同时构建动态服务组合流程。方法操作简单,Warshall算法时间复杂度为O(n3),在服务组合中有较好的实用性。     

基于SOA的Web服务动态组合研究与实现

通过深入分析现有Web服务组合系统优势与不足,将SOA引入到Web服务动态组合领域,提出了一种基于SOA架构和分层协议栈机制构建Web服务动态组合系统的方法,设计并实现了一个基于SOA架构的松散耦合原型系统来实现Web服务组合,可为服务消费者提供一个适当的、开放的、按需配置的及安全的Web服务动态组合环境.     

QoS-Aware Composite Services Retrieval

For current service-oriented applications, individual web service usually cannot meet the requirements arising from real world applications, so it is necessary to combine the functionalities of different web services to obtain a composite service in response to users＇ service requests. In order to address the problem of web service composition, this paper proposes an efficient approach to composing basic services in case no any individual service can fully satisfy users＇ requests. Compared with the general strategies adopted in most previously proposed approaches where only the best composition solution is produced, the QoS-aware service composition approach is given and top k solutions in the framework are provided, rather than focusing on obtaining the best composition solution, since the presented approach allows more candidates that are likely to meet the requirements of the users. The approach is based on a succinct binary tree data structure, and a system,named ATC （Approach to Top-k Composite services retrieval） system is implemented. In ATC, Qos is taken into account for composite service, and a heuristic-based search method is proposed to retrieve top k composite service. Some extensive experiments are designed and two web service benchmarks are used for performance study. The experimental results snow that the proposed approach can assure high precision and efficiency for composite service search.     

基于有界限模型检验的服务建模与自动组合

针对面向服务架构(SOA)体系的Web服务数量快速增长现状,为实现大规模服务场景下高效自动组合Web服务来满足用户复杂需求问题,提出一种基于有界模型检验的Web服务组合方法.其中,Web服务被建模为有限状态自动机,众多Web服务构成服务社区,Web服务组合需求由线性时态逻辑公式描述,通过有界模型检验器的系统化搜索,该方...     

Novel recommendation system based on long-term composition for adaptive web services

In the era of digital web services, composition of features on the fly is inevitable. The Long-term Composed Service (LCS) entertains the composition of features to any extent, since it has an open-ended lifetime. In the proposed research work, we have intended to provide service support to run the business toward a long time commitment. Structure-based recommended system for LCSs (RS-LCSs) is proposed, where user queries and recent updation/requirements are considered for exhibiting the response through the system. In the proposed system, business has been regulated according to the time constraints. We have tested our proposed system on the standard benchmark dataset and quantitative metrics show our proposed method has performed well against the compared methods. The forecasting of business has been done through our model to address the recent queries and new requirements issues to provide an adaptive web service for the business development.     

基于禁忌搜索算法的Web服务组合优化

为有效集成网络中的Web服务,组成满足用户需求的服务链,提出了基于禁忌搜索算法的Web服务组合优化方法.建立了基于QoS感知的Web服务组合优化模型,该模型从全局限制了用户的QoS约束.简述了禁忌搜索算法求解的基本框架,在此基础之上分析了应用禁忌搜索算法求解过程中的关键设计步骤.实例仿真计算结果表明,该算法求解具有比线性规划算法更好的时间性能,并具有与遗传算法相仿的表现.     

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.     

Lifetime service level agreement management with autonomous agents for services provision

In the web services environment, service level agreements (SLA) refers to mutually agreed understandings and expectations between service consumers and providers on the service provision. Although management of SLA is critical to wide adoption of web services technologies in the real world, support for it is very limited nowadays, especially in web service composition scenarios. There lacks adequate frameworks and technologies supporting various SLA operations such as SLA formation, enforcement, and recovery. This paper presents a novel agent-based framework which utilises the agents’ ability of negotiation, interaction, and cooperation to facilitate autonomous SLA management in the context of service composition provision. Based on this framework, mechanisms for autonomous SLA operations are proposed and discussed. Results from simulations show that by integrating agents and web services the framework can address issues of SLA management drawn from sophisticated service composition scenarios.     

基于Petri网的复合Web Service构造与分析

利用Petri网对工作流模型进行分析与验证是目前行之有效的一种方法。该文应用工作流思想研究Web Services的复合问题,利用Petri网技术分析Web Services的调用过程,并对Web Services网进行形式化分析,给出Web Services复合群到工作流网的映射规则。     

面向Web服务的BPEL的研究与实现

BPEL简化了将多个Web服务合成到一个新的复合服务(业务流程)中的操作过程.但如果要进一步提高BPEL流程的开发效率,还需要一个可视化的解决方案.通过一个开发实例的具体实现过程,对基于BPEL进行Web服务合成的原理和方法进行了深入的研究,并由此提出了基于Oracle BPEL流程管理器实现Web服务合成的解决方案,介绍了在该环境下部署和测试一个BPEL流程的方法.