Web服务的可用性测量

利用一种新的消息传递机制,从请求者的角度在服务请求者和服务提供者之间进行消息交互的同时进行Web服务可用性的测量,并提出了一套关于Web服务可用性的量化指标,为服务请求者的选择提供依据.     

基于用户策略的Web服务动态选择方法研究

目前的Web服务选择方法主要是服务关键词语义和属性匹配、运行性能最优评估,未能很好考虑用户对服务质量的个性化需求.对用户需求、服务质量进行模型描述,结合用户策略给出了一个服务评估和选择算法,该算法根据服务请求者的满意度对候选服务进行评估和选择.与已有的服务性能选择方法相比,该方法更能满足个性化需求.     

Web服务组合的可靠性动态评估模型*

为了合理、高效、动态地评估Web服务组合的可靠性,为服务请求者提供高质量的组合服务,提出了一个Web服务组合的可靠性动态评估模型。该模型对服务提供者发布至UDDI注册中心的Web服务进行语义预先处理,根据语义Web服务间的逻辑组合关系,基于预推理技术构造Web服务的自动组合框架,提出了Web服务的自动组合算法,建立Web服务组合方案的路径结构;利用随机Petri网对满足服务请求者需求的服务组合路径结构进行可靠性建模,结合在线获取的Web服务可靠性信息,对Web服务组合的可靠性进行动态评估。实验示例结果分析表明,提出的模型能确保Web服务组合方案的有效性和提高服务组合的效率,对Web服务组合的可靠性评估具有较强动态性和灵活适应性。     

一种基于非功能属性决策的可信Web服务发现模型

Web服务注册中心为服务请求者寻找Web服务带来方便,但由于其缺少对服务非功能信息的支持,无法很好满足用户需求,最终导致服务发现可信程度不高.首先对Web服务质量、服务信誉等非功能属性进行分析,通过服务行为观测机制获取较客观的属性指标数据,利用多属性决策方法,提出一种可信的Web服务发现模型.模型能帮助服务请求者发现最优的、可信的服务.最后通过一个应用实例验证了模型的有效性.     

基于QoS与可信度融合的Web服务选择机制研究

随着Web服务的快速发展,大量相似的Web服务功能发布至Internet。为从Web服务集合中过滤出请求者需求的Web服务,探讨了一种基于QoS与可信度融合的Web服务选择机制。针对Web功能相似的复杂性,剖析了目前选择机制中存在的局限性,借助对服务可信度的综合评估,通过第三方的服务质量监控数据,从主观和客观两个方面评价Web服务选择,基于QoS监控、目标消费群、服务质量评估与评价反馈模型,提出了基于QoS与可信度融合的Web服务选择模型。仿真实验结果验证了该模型既可适应动态变化的环境,又可保证真实的服务质量,克服了评价标准的个体差异性。研究结果表明,提出的服务选择方法是可行与可用的。     

保证服务质量的Web服务优化选取

快速、准确地发现满足用户需求的Web服务是目前Web服务发现的一个研究重点。文中提出了一个基于服务质量的语义Web服务发现框架。首先采用遗传算法来实现服务的聚类预处理,以此来降低服务的查找空间,提高服务的查询效率。进一步,针对服务请求者对服务质量的需求,实现了基于WSMO-QoS的服务匹配策略。最后,实验结果表明了所提方法的有效性。     

多约束的Web服务组合研究

随着Web服务的种类越来越多,具体的请求者对服务组合的要求越来越高。针对目前的组合方式、组合的服务质量以及用户的方便度,提出了多约束的服务组合方案。结合目前请求者和服务提供者之间对WSDL的依赖性及其交流上的不便,把Web语义加入到了Web服务组合的过程中。最后综合考虑用户对服务的满意度,采用动态规划方法,设计了多约束的水平组合解决方案。     

一种基于QoS的Web服务发现模型

当前采用 OWL-S 描述的 Web 服务,主要从服务功能进行描述,缺乏对服务质量的明确刻画,导致服务请求者难以得到最佳服务.针对此问题,本文对 OWL-S 规范扩展,提出一个基于 QoS 的语义 Web 服务发现模型 SWSDM-QoS.该模型支持 QoS 的服务发布、查找和反馈,并在此基础上提出一种 QoS 约束的服务选择算法.本论文创新性之处在于在服务发现过程中加入了服务质量本体信息,使得Web服务在框架内支持QoS约束的语义发现,满足了用户的个性化需求.     

基于WSMO服务质量的语义Web服务发现框架

当前对Web服务进行语义描述最流行的两个框架是OWL-S和WSMO,但它们主要都是从服务功能的角度对服务进行描述,缺乏对服务质量的明确刻画,导致服务请求者难以得到最佳服务.针对此问题,对WSMO规范进行了扩展,定义了一个服务质量(QoS)的元模型--WSMO-QoS,给出了QoS的本体词汇.在此基础上提出了基于QoS的语义Web服务发现框架,并给出一个从基本描述、IOPE、QoS三个层次实现服务匹配的算法.最后,实验结果验证了该服务匹配算法的有效性.     

基于QoS本体的语义Web服务组合策略

随着Web服务技术的快速发展和广泛应用,传统的Web体系结构肯定已经不能满足日益众多的新需求, Web服务和语义Web成为Web发展的两个新兴方向。在他们相互融合下逐步发展成为语义Web服务这一新的技术。本文设计实现一个基于QoS本体的语义Web服务组合原型系统,以服务请求者的QoS需求为主体,再结合QoS语义匹配和QoS数值匹配进行个性化的服务组合,从而能为服务请求者提供能满足请求者个性化需求的Web服务。     

Context-based caching and routing for P2P web service discovery

In modern heterogeneous environments, such as mobile, pervasive and ad-hoc networks, architectures based on web services offer an attractive solution for effective communication and inter-operation. In such dynamic and rapidly evolving environments, efficient web service discovery is an important task. Usually this task is based on the input/output parameters or other functional attributes, however this does not guarantee the validity or successful utilization of retrieved web services. Instead, non-functional attributes, such as device power features, computational resources and connectivity status, that characterize the context of both service providers and consumers play an important role to the quality and usability of discovery results. In this paper we introduce context-awareness in web service discovery, enabling the provision of the most appropriate services at the right location and time. We focus on context-based caching and routing for improving web service discovery in a mobile peer-to-peer environment. We conducted a thorough experimental study, using our prototype implementation based on the JXTA framework, while simulations are employed for testing the scalability of the approach. We illustrate the advantages that this approach offers, both by evaluating the context-based cache performance and by comparing the efficiency of location-based routing to broadcast-based approaches. Recommended by: Zakaria Maamar     

On optimal decision for QoS-aware composite service selection

The increasing popularity of employing web services for distributed systems contributes to the significance of service discovery. However, duplicated and similar functional features existing among services require service consumers to include additional aspects to evaluate the services. Generally, the service consumers would have different view on the quality of service (QoS) of service attributes. How to select the best composite service in theory among available service (WS) candidates for consumers is an interesting practical issue. This work proposes a QoS-aware service selection model based on fuzzy linear programming (FLP) technologies, in order to identify their dissimilarity on service alternatives, assist service consumers in selecting most suitable services with consideration of their expectations and preferences. This approach can obtain the optimal solution of consensual weight of QoS attribute and fuzzy positive ideal solution (FPIS) by extending LINMAP method, developed by Srinivasan and Shocker. Finally, two numerical examples are given to demonstrate the process of QoS-aware web service selection. The experimental results demonstrated that it is a feasible and supplementary manner in selecting the of web services.     

Accessibility and Usability of User-centric Web Interaction with a Unified-Ubiquitous Name-based Directory Service

Web-based information services should be evaluated for accessibility and usability with various types of Internet Web-browsing devices, interacting with web information servers including directory server. A ubiquitous name-based directory server, accessible and usable with a variety of Web-browsing devices (e.g. Internet-capable mobile phones), could be a unified center for human-centric Web interaction services as well as for business models based on personalized services. We studied the accessibility and usability in user-centric Web interaction with a unified-ubiquitous name-based directory service, as metric metadata for real-time estimation. We studied the real-time metrics in synthetic approach for comparison among different services. We show empirical results based on implementation and experiments in Korea, Japan and China.     

Consumer-centric QoS-aware selection of web services

There exist many web services which exhibit similar functional characteristics. It is imperative to provide service consumers with facilities for selecting required web services according to their non-functional characteristics or quality of service (QoS). However, the selection process is greatly complicated by the distinct views of service providers and consumers on the services QoS. For instance, they may have distinct views of the service reliability—wherein a consumer considers that a service is reliable if its success rate is higher than 99%, while a provider may consider its service as reliable if its success rate is higher than 90%. The aim of this paper is to resolve such conflicts and to ensure consensus on the QoS characteristics in the selection of web services. It proposes a QoS Consensus Moderation Approach (QCMA) in order to perform QoS consensus and to alleviate the differences on QoS characteristics in the selection of web services. The proposed approach is implemented as a prototype tool and is tested on a case study of a hotel booking web service. Experimental results show that the proposed approach greatly improves the service selection process in a dynamic and uncertain environment of web services.     

A Usability Checklist for the Usability Evaluation of Mobile Phone User Interface

In the last decade, the research of the usability of mobile phones has been a newly evolving area with few established methodologies and realistic practices that ensure capturing usability in evaluation. Thus, there exists growing demand to explore appropriate evaluation methodologies that evaluate the usability of mobile phones quickly as well as comprehensively. This study aims to develop a task-based usability checklist based on heuristic evaluations in views of mobile phone user interface (UI) practitioners. A hierarchical structure of UI design elements and usability principles related to mobile phones were developed and then utilized to develop the checklist. To demonstrate the practical effectiveness of the proposed checklist, comparative experiments were conducted on the usability checklist and usability testing. The majority of usability problems found by usability testing and additional problems were discovered by the proposed checklist. It is expected that the usability checklist proposed in this study could be used quickly and efficiently by usability practitioners to evaluate the mobile phone UI in the middle of the mobile phone development process.     

一种支持QoS约束的Web服务发现模型

服务质量(QoS)描述了一个产品或服务满足消费者需求的能力．提供有保证的QoS是Web服务在商业应用中获得成功的关键．如何动态地选择出最适合用户需求的Web服务正在引起研究领域的关注．该文提出了一种支持QoS约束的Web服务发现模型(WSDM-Q)．该模型定义了一组描述Web服务QoS及信誉度的分类tModel,引入了QoS量化的概念,采用了QoS协商和反馈机制,支持携带QoS描述信息的服务发布和基于QoS约束的服务发现．协商机制允许服务提供者根据运行时的状态对服务请求进行接纳控制,反馈机制允许服务注册中心对服务提供QoS的信誉度进行动态评估和调整。该模型不需要改变UDDI的内部实现,能够直接在现有的UDDI服务上进行扩展．作者已经基于Mierosoft.Netf平台和Microsoft UDDI服务实现了一个原型系统．     

基于监视的服务质量评估方法

在面向服务的体系结构(Service Oriented Architecture,SOA)中,消费者的目标是发现和使用高质量的服务。随着Web服务数量的不断增加,为用户推荐和选择最满足需求的Web服务已经成为服务计算领域最重要的挑战之一。在SOA中,传统的质量评估方法偏重于消费者获得更高的性能,未充分考虑消费者的个性化需求,这样,并不一定让消费者获得完全满足其需求的服务。因此,在服务选择和推荐过程中不仅需要考虑服务的功能性需求,还需要考虑服务的非功能性需求。而且,服务质量的改变只能在服务运行过程中才能被发现。为了解决上述问题,本文提出一种基于监视的服务质量评估方法,充分考虑服务的功能性和非功能性属性,建立统一模型,根据监视数据动态评估服务质量,为动态环境下选择和推荐服务提供依据。本文最后描述了该方法的实现框架。     

Usability testing in 2000 and beyond

Usability testing is a widely used technique to evaluate user performance and acceptance of products and systems. It was introduced in the late 1980s and rose to popularity in the past decade. This paper provides a view of the current status of usability testing as a method and describes how it will be used in the 21st century. Although usability testing may not be the most efficient technique for discovery of usability problems, it is a reliable way to estimate quantitatively users' performance and subjective satisfaction with products. Four major trends in usability testing include: common reporting formats and methods for industry; Internet application and website testing; testing of mobile, handheld devices; and testing in more naturalistic environments such as simulated homes and classrooms. In the 21st century, 'quick and clean' usability testing methods are needed to provide valid and reliable data on how well people use products and systems, and how they like using them.     

Usability testing in 2000 and beyond

Usability testing is a widely used technique to evaluate user performance and acceptance of products and systems. It was introduced in the late 1980s and rose to popularity in the past decade. This paper provides a view of the current status of usability testing as a method and describes how it will be used in the 21st century. Although usability testing may not be the most efficient technique for discovery of usability problems, it is a reliable way to estimate quantitatively users' performance and subjective satisfaction with products. Four major trends in usability testing include: common reporting formats and methods for industry; Internet application and website testing; testing of mobile, handheld devices; and testing in more naturalistic environments such as simulated homes and classrooms. In the 21st century, ‘quick and clean’ usability testing methods are needed to provide valid and reliable data on how well people use products and systems, and how they like using them.     

Factors Affecting Web Portal Information Services Usability: A Canonical Correlation Analysis

This study employed canonical correlation analysis to determine which of the possible combinations of student, web portal design, and objective measure-related factors might influence both frequency and satisfaction of use of the web portal information services (WPIS). Data gathered from the two studies revealed that usability of WPIS is a combination of self-initiative, commitment, content, availability, speed, esthetics, ease of use, and effectiveness of WPIS. Thus, the null hypothesis stating that the predictor variable set cannot explain any of the variance of the dependent variables was rejected. It was concluded that the WPIS usability was more sensitive to design-related factors than the student-related factors. It was likewise shown that effectiveness is a design consideration and not a dimension of usability in the context of web portal. Further, it was disclosed that initiative and commitment and not external pressure influence the usability of WPIS. Limitations and recommendations were also offered.