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面向服务的软件开发方法减少了开发应用程序的时间和复杂度。当前面向服务架构中的服务注册和发现主要关注于服务的接口描述和静态属性,却较少考虑服务行为和服务质量。对服务行为即外部可见的操作序列的忽视,可能导致服务产生运行时的异常和错误;忽视服务质量即其运行时的质量信息,则可能导致系统运行的低效。本文提出了一种扩展的面向服务的软件开发过程,探宄服务交互过程中其行为一致和质量匹配。在面向服务的组件模型OSGi平台上,采用动态AOP技术,设计了一种支持服务行为和服务质量的中间件系统。该系统不但保证服务发现的调用一致性和服务替换的观察一致性,而且支持对服务运行时操作行为的检测和服务质量信息的收集,从而保证选择最佳的服务实现,提高应用系统的运行效率。 相似文献
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增值服务是在原有网络的软硬件基础之上进行的功能开发,它在不影响原系统功能的前提下实现功能附加,使网络功能得到增值.本文引入形式化描述技术,提出了基于协议形式化描述的网络增值服务开发方法,并通过对文件传输协议的描述讨论了该方法的具体应用.最后总结了该方法在实际网络增值开发中的应用技术. 相似文献
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基于组件的软件开发方法成为当前软件开发的一个新的重要方法,但是如何合理地划分组件的粒度,使组件的重用性与可维护性达到最佳平衡是非常困难的。为此,论文研究了计划调度系统的组件技术,建立了计划调度系统的组件层次结构。在介绍GenVoca模型的基础上,对它进行了扩展,然后用它实现系统的组件层次结构的形式化描述。 相似文献
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现有的服务发现研究大多基于功能,以服务为粒度考察服务.而服务是以操作为粒度与用户进行交互的.服务发现与使用粒度上的差异,使服务不能发挥最大效能.为此提出了一种从业务层面,以操作为粒度,考察服务对用户需求业务适用程度的服务发现方法.通过定义面向业务应用的服务与用户需求描述模型,建立领域业务应用本体为服务提供者和使用者的业务级交互奠定基础.通过服务与用户业务需求的深层匹配,在发现可用服务及其操作的同时,对服务的业务规范性和业务完备性进行评估.最终给出了一种面向业务应用的服务发现方法. 相似文献
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该文首先介绍了当前服务粒度划分研究现状,并对几种主流服务粒度划分方法进行分析,指出了它们的不足之处,进而提出了一种基于业务、组件、类的混合模式两级抽象粒度划分方法——TAMM,该方法利用混合模式并结合java设计模式思想对服务粒度划分过程进行两级优化组合抽象,以适中的粗细粒度优化组合抽象服务,从而提高服务的稳定性、灵活性及性能。最后,结合实际案例对该划分方法的特性进行了分析说明。 相似文献
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服务请求代理是工作在分布式网络环境中的一组应用程序,它为分布式网络环境中的应用程序提供互操作功能。它就像一个"通讯总线",使程序间可以透明的发送请求和接收响应。本文描述了"冶金过程控制系统开发平台"的核心组件--服务请求代理的设计与实现过程,并简单介绍了该系统在工程中的应用情况。 相似文献
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Dr. Alexander Krammer Prof.?Dr. Bernd Heinrich Dr. Matthias Henneberger Dr. Florian Lautenbacher 《WIRTSCHAFTSINFORMATIK》2011,53(6):331-345
Service-oriented architectures are widely discussed as a design principle for application and enterprise architectures. Nevertheless, an adequate granularity of services has not yet been researched sufficiently from an economic perspective. The finer the granularity to realize the functions of a process, the higher the number of services is, and the more effort has to be directed towards composing them. In contrast, very coarse-grained services bear the disadvantages of higher implementation costs and lower reuse potential (e.g., in different processes). The aim of the decision model proposed in this paper is to determine an adequate granularity of services from an economical perspective. Thus, degrees of freedom, which often exist for the choice of granularity after a domain analysis, can be leveraged to realize a cost-efficient solution. We illustrate the applicability and practical benefits of the decision model with an example from the context of a financial services provider. 相似文献
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《Multimedia, IEEE Transactions on》2009,11(4):716-729
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In this paper, a methodology is presented and employed for simulating the Internet of Things (IoT). The requirement for scalability, due to the possibly huge amount of involved sensors and devices, and the heterogeneous scenarios that might occur, impose resorting to sophisticated modeling and simulation techniques. In particular, multi-level simulation is regarded as a main framework that allows simulating large-scale IoT environments while keeping high levels of detail, when it is needed. We consider a use case based on the deployment of smart services in decentralized territories. A two level simulator is employed, which is based on a coarse agent-based, adaptive parallel and distributed simulation approach to model the general life of simulated entities. However, when needed a finer grained simulator (based on OMNeT++) is triggered on a restricted portion of the simulated area, which allows considering all issues concerned with wireless communications. Based on this use case, it is confirmed that the ad-hoc wireless networking technologies do represent a principle tool to deploy smart services over decentralized countrysides. Moreover, the performance evaluation confirms the viability of utilizing multi-level simulation for simulating large scale IoT environments. 相似文献
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数据流中一种快速启发式频繁模式挖掘方法 总被引:10,自引:0,他引:10
在现有的数据流频繁模式挖掘算法中,批处理方法平均处理时间短,但需要积攒足够的数据,使得其实时性差且查询粒度粗;而启发式方法可以直接处理数据流,但处理速度慢.提出一种改进的字典树结构--IL-TREE(improved lexicographic tree),并在其基础上提出一种新的启发式算法FPIL-Stream(frequent pattem mining based on improved lexicographic tree),在更新模式和生成新模式的过程中,可以快速定位历史模式.算法结合了倾斜窗口策略,可以详细记录历史信息.该算法在及时处理数据流的前提下,也降低了数据的平均处理时间,并且提供了更细的查询粒度. 相似文献
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Zaiwen Feng Rong Peng Raymond K. Wong Keqing He Jian Wang Songlin Hu Bing Li 《Information Systems Frontiers》2013,15(4):553-567
Composition of Web services can be very complex, and usually involves multiple atomic services and varieties of message exchange patterns. Worst still, with the increasing amount of available services with varying granularity and quality, selecting the best combination of services becomes very challenging. This paper addresses the issues on multi-granularity service composition with awareness of the service quality. In particular, we consider how a new service composition plan is produced, while preserving its original observable behaviors of a service that are shown to the service user, by substituting the service with another service or a set of services of finer or coarser grain. The new plan aims to have services of better quality (if the corresponding underlying services are available). To achieve this, we firstly define a behavioral signature model to capture observable behaviors of services. We then present that two service composition plans are choreography equivalent if they comply with the same behavioral signature model. We then propose a behavioral extracting algorithm to obtain the behavioral signature model from a service composition plan. We also present a method to determine choreography equivalence. Finally we briefly describe our prototype implementation that captures all these proposed algorithms. 相似文献
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随着Internet的飞速发展,符合J2EE规范的Web容器已经成为部署企业Web应用的主流平台.同时,企业Web应用的多样化和复杂性的增长,迫切地要求Web容器提供差分服务的支持.然而,传统的Web容器采用尽力而为的服务模型,无法提供差分服务支持.已有的研究采用准入控制、优先级调度等方法来为Web容器提供差分服务支持,但是它们只能提供单调、静态的差分服务策略.提出了一个基于自管理单元的Web容器DSWC,它能够根据SLA定义提供两级差分服务支持.此外,提出了一个自适应差分服务策略选择算法,它能够根据动态变化的运行环境自适应地选择差分服务策略.原型系统的实验结果显示,DSWC能够有效地为请求提供符合SLA定义的细粒度的差分服务支持. 相似文献
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在大型信息系统的设计中,访问控制一直是一项复杂的工作。基于角色的访问控制(RBAC)被推荐来代替传统的访问控制模型。应用到信息系统中时,需要解决RBAC的控制粒度问题。我们需要一个能够基于上下文进行细粒度访问控制的RBAC模型,即基于对象实例上下文上的访问控制。对现有的解决方案进行综述和比较,提出了使用会话期上下文检查的RBAC模型:RBACCCS。RBACCCS中用了参数化权限,在权限检查时用上下文变量实例化这些参数化权限,这样就解决了上下文的表示和上下文作用机制问题。最后对RBACCCS模型进行 相似文献
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方丁 《计算机应用与软件》2012,29(5):215-218
机场运营信息系统集成对适应我国航空业务量的增长和提高机场服务质量具有关键影响,但传统的机场运营系统采用点到点的集成方式,僵化而缺乏柔性。基于SOA的系统集成具有松耦合、粗粒度、灵活性高等特点,适合机场运营系统集成的需求。给出基于SOA的机场运营系统集成的总体架构设计,并采用基于设计结构矩阵(DSM)聚类的方法进行业务服务设计,该方法首先分析航班业务流程,其次使用DSM对活动间的依赖性进行建模,最后采用聚类方法实现服务设计及接口设计。 相似文献
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《国际计算机数学杂志》2012,89(11):2201-2220
Substitutability of Web service is the key aspect for ensuring reliability of Web service-oriented software. Along with more large and coarse granularity services appear across the Internet continuously, it has become a new challenge that how to determine the substitutability between different granularity services. In this paper, we propose the notion of interface inverted dependence to reveal all functions and business logic of large granularity services. A formal model is bulit by extending the Martin-Löf's type theory. The model can clearly describe both large and small granularity services from three aspects: syntax, semantics, and behaviour. Based on the formalization, we introduce the notions of substitutability between different granularity services with different stringency through considering the context of services. In order to judge the substitutability, a mechanism based on subtyping theory is proposed. At last, the case study is given to show the effectiveness of the proposed substitutability. 相似文献