保障QoS的服务决策系统的研究与设计

随着Web服务架构在企业信息化中应用的普及,针对Web服务的服务质量(QoS)需求,提出了多Agent协作机制下保障QoS的服务决策系统;通过对传统的Web服务架构的研究,扩展了UDDI注册中心,使其能够实现QoS属性的描述、发布、查询和更新;在此基础上加入了用户Agent、服务商Agent和决策Agent,在多Agent协助和交互的机制下,给出主客观赋权排序的群决策算法;算法综合考虑了QoS的主观需求和客观条件,使系统实现保障QoS的服务决策。     

一种基于信任的Web服务发现方法

在面向服务的环境下,由于Web服务本身的动态性和网络环境的不确定性,致使用户很难获得可信的高质量服务。当前基于反馈信息的信任评估方法没有考虑恶意评估对服务可信程度的影响,本文通过加入客观评价对此进行了修正,并提出一种从服务的能力、稳定性和声誉三方面来建立的Web服务信任模型,提升了信任评估的准确度。在此基础上提出一种可信的Web服务发现框架,通过服务交易历史信息获取比较客观的信任属性,同时结合非功能属性进行服务的综合评估,利用熵值法来确定其中各非功能属性的权重,从而发现满足用户需求的可信服务。仿真结果表明,该方法是可行和有效的。     

Agent based intelligent search framework for product information using ontology mapping

The Semantic Web and Web services provide many opportunities in various applications such as product search and comparison in electronic commerce. We implemented an intelligent meta-search and recommendation system for products through consideration of multiple attributes by using ontology mapping and Web services. Under the assumption that each shopping site offers product ontology and product search service with Web services, we proposed a meta-search framework to configure a customer’s search intent, make and dispatch proper queries to each shopping site, evaluate search results from shopping sites, and show the customer the relevant product list with associated rankings. Ontology mapping is used for generating proper queries for shopping sites that have different product categories. We also implemented our framework and performed empirical evaluation of our approach with two leading shopping sites in the world.     

融合可信性评价的Web服务组合QoS优化

针对复杂网络环境下存在的恶意欺诈行为,提出一种将服务可信性评价和基于QoS感知的服务组合优化相结合的方法框架.首先,基于Web服务的历史行为分别采用贝叶斯学习理论和用户评价方法,从客、主观两方面对Web服务可信性进行评估;然后,利用可信性度量后的QoS属性构建多目标优化模型,并提出一种改进的多目标灰狼优化(IMOGWO)算法用于模型求解;最后,通过实验数据验证所提出方法框架在服务组合优化时的有效性.     

基于策略的Web服务非功能属性匹配

Web服务的非功能属性匹配对增强Web服务发现的准确性,保证Web服务调用质量具有重要作用。目前Web服务的非功能属性匹配研究一般局限于某一具体的非功能属性,缺少支持各非功能属性的统一匹配方法。该文提出了一种基于策略的Web服务非功能属性的匹配方法,把Web服务非功能属性作为服务双方的策略,利用策略匹配来实现非功能属性的匹配。采用WSPL作为策略描述语言,并提出了层次化策略的概念,利用不同的发布方式对不同层次的策略进行发布,服务发现的过程与不同层次的策略匹配结合在一起。该方法支持各种非功能属性的匹配,并可以容易地和Web服务的功能性匹配方法结合到一起,形成完整的Web服务发现匹配系统。     

A framework and ontology for dynamic Web services selection

Current Web services standards lack the means for expressing a service's nonfunctional attributes - namely, its quality of service. QoS can be objective (encompassing reliability, availability, and request-to-response time) or subjective (focusing on user experience). QoS attributes are key to dynamically selecting the services that best meet user needs. This article addresses dynamic service selection via an agent framework coupled with a QoS ontology. With this approach, participants can collaborate to determine each other's service quality and trustworthiness.     

应用于Web服务合成的一种有效的Web服务发现策略

随着Web服务的流行，如何发现Web服务为研究者们提出了挑战．文中将描述Web服务的信息分为服务操作信息（OWSDL）、服务功能信息（一般属性）和服务约束信息（实例属性）．基于描述服务的三部分信息，分三步实现服务查找．第一步，基于领域本体商业规范OWSDL实现服务操作同构；第二步，基于服务概要描述的一般属性，满足服务的功能需求；第三步，应用服务匹配度模型，基于概要描述的实例属性，按需为消费者提供恰当的服务．最后，通过实例证明了该方法是一种有效的Web服务发现策略．     

虚拟计算环境中服务行为与质量的一致性

提出了一种用Petri net对服务行为和服务质量进行统一建模的框架.基于该框架所提出的统一的服务行为和服务质量的一致性规则可以在服务的查找和替换中综合判断服务行为和服务质量的一致性.自行开发的SOBECA(service-oriented, behavior and capability support architecture)中间件系统在现有的Web服务标准上增加了服务行为和服务质量的描述,可以更好地自动化支持服务行为和服务质量的一致性检查,同时也验证了上述框架的合理性.     

基于实体-数据的物联网服务建模

物联网服务作为信息世界软件服务通过物联网向现实世界的延伸,其在物联网系统具有重要的作用.然而,不同于传统Web服务,物联网服务具有现实感知、数据驱动、异构分布、时空相关等新特点,使得现有的服务模型不足以对物联网服务有效刻画,进而也不能满足物联网应用中的后续服务发现、服务卸载、服务组合等需求.在凝练分析物联网服务建模需求和已有物联网服务模型的基础上,提出了一种基于实体-数据的物联网服务建模框架,该框架提出了服务、实体、数据三元信息融合的物联网服务模型概念及概念关系,重点定义了服务、实体、数据的时空属性及时空依赖关系,以支持基于时空相关性的物联网服务关联表示与分析,并通过扩展OWL-S(ontology Web language for services)给出了基于实体-数据的物联网服务描述方式.最后,结合一个高速公路物联网应用案例对模型的使用方式和效果进行了讨论.     

一种动态混合QoS语义的Web服务个性化推荐模型

服务推荐是服务计算中的主要问题之一,当前大多针对功能属性进行推荐,而在Web服务的QoS属性方面考虑较少,并且不支持动态变化的QoS属性。基于动态混合QoS的语义Web服务个性化推荐模型,把语义Web技术引入Web服务中,在QoS监控器下,有效监测Web服务的QoS属性变化并动态更新Web服务的QoS属性。根据建立的用户兴趣模型,向用户推荐具有个性化的Web服务。此外,在个性化推荐系统中使用最广泛的协同过滤推荐技术基础上,对数据进行了一系列的预处理填充,而且充分考虑了不同时间的项目评分对推荐的影响。结合用户兴趣度和用户评分的相似性计算方法,并通过不同的权值来表示它们的重要程度,综合计算目标用户的最近邻居集合,最终对用户u产生推荐。该系统在一定程度上提高了服务推荐的效率和准确度并满足用户查询需求。     

基于网关服务缓存和QoS的服务发现机制

在服务描述语言上增加QoS描述,通过QoS认证中心管理和量化服务的QoS属性,实现Web服务的QoS属性描述。在此基础上,设计一种基于网关服务缓存和QoS的服务发现机制,通过代理服务网关对Web服务进行筛选,同时维护一个虚拟服务缓存管理历史服务请求信息,减少服务请求过程中重复的服务发现过程,提高服务发现性能,并通过实验验证其正确性和有效性。     

A business model for deploying Web services:A data-centric approach based on factual dependencies

The standards XML, SOAP, WSDL and UDDI allow (i) services to be accessed and executed via the Web; and (ii) a loose coupling of these services. Thanks to these standards, Web services technology is becoming not only a de facto integration standard, but also a de facto Internet standard instance of the SOA architecture. However, the deployment of such a technology is still hindered by some technical as well as methodological issues. This paper proposes a business model with multiple interfaced abstraction levels as a framework to methodologically deploy Web services technology with respect to SOA architecture. The attributes describing the business objects and coordination artifacts as described in the highest abstraction level of the business model, i.e. the universe of discourse, are aggregated according to a time/space constraint called factual dependency. Each aggregation of factually dependent attributes is validated with regard to an actual business event. The aggregation is then interfaced to lead to a well-specified Web service. The resulting comprehensive set of consistent Web services are then registered in a public or a private UDDI to be discovered and invoked by any business process. The proposed Web services generation process aims at unlocking and turning informational assets into actions. It differs from the current IT perspective approaches that generate Web services directly from redundant and inconsistent elements in the enterprise information systems.     

Research on dynamic business composition based on web service proxies

Web services-based business composition brings a number of advantages to the enterprise application development. How to select and compose the web services based on their functionality and QoS (Quality of Service) dynamically prove to be more and more important. In this paper we develop a proxy-based framework to compose Web services dynamically. The framework is featured with a QoS model, an effective service discovery and selection algorithms to facilitate the dynamic integration of Web services and management of abnormalities. Furthermore, a business process constructing method based on service slice is put forward to satisfy the users’ personalized requirements more effectively and flexibly. Our study concerns both functionality and QoS characteristics of Web services to identify the optimal business process solutions. A Complete case study is also included in this paper and the performance demonstrated that the framework and algorithms can provide a tangible and reliable solution to dynamic Web service composition and adaptation.     

A unified framework for managing Web-based services

The emergence of Web technologies enables a variety of Web-based service applications, which can be examined from business process integration, supply chain management, and knowledge management perspectives. To categorize existing Web-based services while foreseeing potential new types, a unified view is needed to represent the structures and processes of Web-based services. This paper proposes a general framework to identify essential structures and operations of Web-based services, and then models these components. We articulate the framework with Web technologies, such as Web service and semantic Web, multi-agent and peer-to-peer, and Web information retrieval and mining. Two comprehensive examples in insurance and knowledge services are used to elaborate the use of Web-based service framework in fulfilling business processes. This study synthesizes essential structures and processes of Web-based services to build a framework for researchers and practitioners to develop Web-based services and techniques.