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.     

一种Web服务组合的可信评估方法

软件可信性日益成为软件工程研究中的热点问题,作为软件资源主要形态的Web服务的可信性也受到了越 来越多的关注。目前对于Web服务可信性的研究主要集中在单一服务QoS属性的可信评价,而针对服务组合的可信 性研究较少。提出了一种通用的原子服务可信评佑模型,并结合原子服务在服务组合执行时的权重,给出了一种基于 结构分析的服务组合可信性的评估方法。最后,结合网络购物实例描述了服务组合可信性评估方法的实验过程。     

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.     

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。     

Toward Quality-Driven Web Service Discovery

Service-oriented architectures follow the find-bind-execute paradigm, in which service providers register their services in public or private registries, which clients use to locate Web services. If a service registry has information on a service that matches a client's criteria, it provides a contract and an access point. Web service discovery is a key component in service-oriented computing. However, without Web service quality standards and quality-based discovery mechanisms, the trustworthiness of business-to-business interactions can't be guaranteed.     

Agent技术在Web服务中的应用探讨

Web服务是一组采用面向服务的体系架构的基于标准的Web协议的软件构件,而Agent是一种在某个环境中自主行动以实现其设计目标的智能化软件实体.Web服务与多Agent系统(MAS,Multi-Agent System)在架构、范例和技术方法等方面具有很大的相似性.Web服务的可信性是未来计算机软件发展关键的问题,实现Web服务在分布式环境下的协同式测试具有一定的挑战性.本文在探讨Web服务与Agent技术的共性的基础上,分析并总结了Agent技术在Web服务中的应用.针对Web服务测试的开放性、协同性、动态性和不确定性等特点,结合Agent系统的自主性、反应性、适应性和社会性,本文提出了一种基于MAS的Web服务测试框架(MAST,Multi-Agent-based Service Testing),并对其关键技术进行了探讨.     

一个Web服务可信体系结构

Web服务的安全可信问题是影响其广泛应用的重要因素。已有的解决方案大多从安全角度出发,但对于服务面对攻击或安全威胁时仍能按照预期工作则缺乏考虑。从Web服务的安全可信需求出发,对安全的概念进行了拓展,提出了可信的目标和内涵。在此基础上,提出一个以安全交互、联合身份和分布策略为基础,以运维管理、共用机制为支撑的Web服务可信体系结构,其可为Web服务安全可信提供体系结构层面的支持。     

基于SOA的人工影响天气业务平台解决方案

为提高人工影响天气业务系统的服务水平,针对目前系统存在的不足,通过研究面向服务架构(SOA)和WebService技术,提出了基于面向服务架构(SOA)的人影作业综合业务平台解决方案.给出一个采用Web Service技术设计实现的四层结构的面向服务的基础框架,即分为基础数据层、服务提供层、业务应用层、用户表现层.阐述该框架在WebGIS平台上实现方法,验证了方案的可行性.为构建人影业务系统平台提供一种可行且优越的方案.     

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.     

Web服务可信证据收集与评估机制研究

现有Web服务的可信评估机制大多忽视Web服务使用者及应用场景的差异性,其评估结果的准确性无法得到保证。提出了一种基于可信证据的Web服务可信评估机制,实现了可信证据的Web服务调用主动探测、服务容器自动反馈和用户反馈收集,同时提出了一种基于用户反馈的上下文敏感可信评估方法,全面考虑了Web服务质量属性的上下文相关性,进一步提高了Web服务可信评估的准确性。     

A reputation assessment model for trustful service recommendation

Nowadays, software systems are mainly Web front-based, Cloud-deployed and accessible by a wide audience over the Internet. These online systems commonly rely on Service-oriented Architecture principles, where they are built as orchestrations of RESTful (and in some rare cases as SOAP-based) services. Integrating new services in an existing orchestration is a challenging and risky task because trustworthiness of these services is not guaranteed throughout their lifetime. Reputation of services is a good indicator about the overall quality of services, because it reflects consumer satisfaction regarding the service-offered functionality and quality. Thus, reputation of services could be considered in the selection and recommendation of trustworthy services. In this paper, we present a framework for the management of web service reputation to conduct a better service recommendation. We present a reputation assessment model that aggregates fair user feedback ratings. The model includes a mechanism that prevents the introduction of malicious feedback ratings, by penalizing detected specious users. In addition, this framework includes a bootstrapping technique for estimating reputation of newcomer services based on neighbor similarity and initial advertised QoS. A set of experiments has been conducted to evaluate the effectiveness of the proposed framework. The results of these experiments highlighted the potential of our framework. These are presented at the end of the paper.     

基于Web Services的电子政务及其安全实现

对Web Services的体系结构及其标准和技术进行了分析,提出了一种基于Web Services的电子政务系统集成框架,并在此基础上以Web服务的方式引入公开密钥基础设施PKI/CA,对电子政务基于Web Services技术的安全实现作了进一步的探讨。     

基于PKI／PMI的Web服务安全框架

Web services的安全性是影响其能否被广泛应用的关键因素之一.目前,Web services的安全性研究主要集中在对XML的扩充和制定Web services安全规范方面,但是这些规范仅描述了安全模型的框架,实用性较差.本文利用PKI/PMI技术,在不需要改变现有Web services协议的基础上,提出了一个基于PKI/PMI的Web服务安全框架,并给出了服务授权和访问控制的算法.     

缺陷驱动的Web服务可信性度量模型*

为了避免Web服务可信性正面度量难以收集数据的问题,提出缺陷驱动的Web服务可信性度量模型TWSMM-SD（trustworthy Web services metrics model based on software defect）,利用Web服务中的缺陷数目及类型来间接评测Web服务的可信度。在对Web服务中出现的缺陷进行全面收集、详细分类和可信归类的基础上,TWSMM-SD根据缺陷的演化来确定每种缺陷对最终可信度的影响程度,将其综合形成此种缺陷的初始权重,再利用隐马尔可夫模型对其进行处理,进而利用     

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。     

XML-based specification for Web services document security

The Internet and related technologies have seen tremendous growth in distributed applications such as medicine, education, e-commerce, and digital libraries. As demand increases for online content and integrated, automated services, various applications employ Web services technology for document exchange among data repositories. Web services provide a mechanism to expose data and functionality using standard protocols, and hence to integrate many features that enhance Web applications. XML, a well-established text format, is playing an increasingly important role in supporting Web services. XML separates data from style and format definition and allows uniform representation, interchange, sharing, and dissemination of information content over the Internet. XML and Web services provide a simplified application integration framework that drives demand for models that support secure information interchange. Providing document security in XML-based Web services requires access control models that offer specific capabilities. Our XML-based access control specification language addresses a new set of challenges that traditional security models do not address.     

一种Web服务可信度测试方法

在深入分析Web服务不确定性的基础上,提出一种Web服务测试方法.通过引入可信度阈值进行检验,该方法对异常候选服务具有较强的抗干扰性,能够有效测试出候选服务的可信度、每个测试用例的期望标准输出及其测试能力.该方法根据可信度对候选服务进行排序,为服务使用者选择合理的Web服务提供了重要参考依据.该方法不仅可以测试单个Web服务,还能够对组合Web服务进行测试.最后,通过测试实验验证了该方法的可行性和有效性.     

DynaGrid: An Adaptive, Scalable, and Reliable Resource Provisioning Framework for WSRF-Compliant Applications

The Web Services Resource Framework (WSRF) is a set of specifications which define a generic and open framework for modeling and accessing stateful resources using Web services. This paper proposes DynaGrid, a new framework for WSRF-compliant applications. Many new components, such as ServiceDoor, Dynamic Service Launcher, ClientProxy, and PartitionManager, have been introduced to offer adaptive, scalable, and reliable resource provisioning. All of these components are implemented as standard WSRF-compliant Web services, hence DynaGrid is complementary to the existing GT4. Our experimental evaluation shows that DynaGrid effectively utilizes Grid resources by allocating only the required number of resources adaptively according to the amount of incoming requests, providing both the scalability and the reliability at the same time.