业务需求变化敏感的服务虚拟化机制

为支持在用户主导、虚拟组织形态的问题求解环境中,透明访问分布、异构的Web服务资源,提出一种支持业务需求变化性的服务虚拟化机制。基于业务需求变化性的描述方法,给出了蕴含变化性的虚拟服务的描述模型,并基于服务匹配、变换以及特征的求解方法,提出了支持需求变化性的虚拟服务与Web服务之间的虚拟化和具体化操作。分析和实验表明,该机制在支持用户需求变化性的同时,提高了用户使用服务的效率。     

网格环境中一种有效的Web服务资源组织机制

Web服务资源的有效组织与获取是网格计算中的关键性问题．基于OGSA(open grid service architecture)框架提出了一种有效的网格Web服务资源组织体系模型，它将Web服务资源的逻辑结构与物理资源组织分开，以层次结构的Web服务解析系统(Web services name system，WSNS)来进行Web服务资源查找与定位，以区域自治系统(area autonomy system，AAS)来进行Web服务资源的维护．详细描述了该模型的实现机制、组织协议与数据结构．通过对模型的分析和对原型系统的模拟表明该模型是合理而有效的：它可以在较小开销下获得较满意的资源组织与定位性能，能适应网格Web服务资源的异构、复杂与动态性、多级的负载平衡和良好的可扩展性．’     

Web机群服务质量控制自管理模型

基于服务类别的资源请求和服务等级给出一种资源划分策略,对各类别的服务请求状态进行建模,使用反馈控制理论的方法对各类别资源进行动态调整,与资源调整规则相结合,以适应访问的突发性和保证服务质量要求,实现了Web机群服务质量的自管理。实验表明自管理模型能有效支持区分服务质量和资源效用控制。     

一种支持业务端编程的服务虚拟化机制VINCA-VM

针对服务环境下使能业务用户按需快速构建应用的需求,提出一种支持业务端编程的服务虚拟化机制,旨在将软件层面的Web服务通过抽象和转换等手段绑定到业务用户可理解的、易于使用的业务级服务．文中重点研究了服务虚拟化运算及其性质,提出一套虚拟化操作原语,并设计和实现了相应的服务虚拟化工具．结合实际应用案例,展示和讨论了服务虚拟化机制及其软件工具的效果．     

基于Wrapper和WSRF的服务等级监控机制

针对服务等级的监控提出了一种基于Wrapper的监控机制,该机制以WSRF下有状态的Web服务(WS-Resource)为基础,用Wrapper将服务提供方提供的服务进行包装再发布,从而在客户端访问这些包装过的服务接口时能够采集监控相关的信息,执行监控操作。采用Wrapper的最大优点是可以屏蔽不同服务提供方的异质性,简化监控系统的实现,甚至可以直接编译服务等级定义得到监控程序代码,并且通过将监控信息发布为资源,简化和管理第3方之间的合作。     

基于语义匹配复杂Web服务的算法研究

目前,Web服务发现机制中以关键词搜索方式进行服务匹配,忽略人类语言的多样性,造成较低的匹配率,同时单个Web服务无法满足客户面向业务过程的商业需求.本文研究一种基于语义匹配复杂Web服务的算法,在服务注册机制中对复杂Web服务匹配进行预处理,Web服务请求到达进行二次匹配,匹配单个Web服务或面向业务过程的一组Web服务.     

一种支持业务用户编程的服务虚拟化技术--VINCA聚合服务机制

提出一种支持业务用户编程的服务虚拟化技术——VINCA聚合服务机制，其核心是VINCA聚合服务模型．该模型从业务与IT两个层面出发并“中间相遇”来实现服务资源的虚拟化，从而屏蔽具体服务资源的使用复杂性，使得业务用户更易于直接将业务需求映射到虚拟化的服务资源，为业务用户编程提供支持．定义了VINCA聚合服务的生命周期模型及使用方式，以明确地指导VINCA聚合服务的构造及使用过程．介绍了VINCA聚合服务支撑系统架构，并结合奥运综合信息服务系统的应用场景展示了VINCA聚合服务机制的效果．     

基于SOA的区域内高校校际间网上资源共享和协作服务模式研究*

为了提高高校资源的利用率,利用当前各高校信息化工作的成果,提出了一个基于SOA的Web服务组合的校际间资源共享协作服务的方案。该方案立足各高校已建成业务系统,对原有功能进行Web服务封装,利用Web服务复用,通过工作流引擎驱动业务流程的模式,满足校际间逻辑业务的新需求。该协作服务模型有别于高校内部应用整合的系统集成方案,是一种松耦合的业务功能组合模式,高校内原有业务系统的升级改造不会影响校际间的逻辑业务功能的实现。该成果适用于新建业务与原有业务没有严格上下级关系的应用场景。     

一种面向Web服务的门户组件机制的设计与实现

通过门户组件（Portlet）来访问以Web服务形式提供的软件服务并展现其结果是通过门户（Portal）访问Web服务的一个核心问题。文中提出一种面向Web服务展现的Portlet（以下简称WSPortlet）机制来解决上述问题，通过遵循业界主流的Portlet规范，使用XSLT来对XML文档进行转换等途径保证了WSPortlet的规范性、有效性和灵活性，并且自主研发实现了WSPortlet系统（以下简称WSPS）。     

一种有QoS保障的Web服务组合方法

随着可用Web Services数量的快速增长，如何根据用户的需求来自动组合Web Services，生成满足用户需求的组合业务，成为一项亟待解决的课题。提出了一种基于QoS的启发式算法，通过该算法，动态调用Web Services来自动生成满足用户所需目标的Web Service组合．同时，该算法还能够根据Web Services组合经验，对以后的Web Services组合方案进行调整。实验结果表明：该算法能够很好地适应网络上Web Services的不确定情况，与同类算法进行性能比较，也显示出较好的性能。     

Harmonic proportional bandwidth allocation and scheduling for service differentiation on streaming servers

To provide ubiquitous access to the proliferating rich media on the Internet, scalable streaming servers must be able to provide differentiated services to various client requests. Recent advances of transcoding technology make network-I/O bandwidth usages at the server communication ports controllable by request schedulers on the fly. In this article, we propose a transcoding-enabled bandwidth allocation scheme for service differentiation on streaming servers. It aims to deliver high bit rate streams to high priority request classes without overcompromising low priority request classes. We investigate the problem of providing differentiated streaming services at application level in two aspects: stream bandwidth allocation and request scheduling. We formulate the bandwidth allocation problem as an optimization of a harmonic utility function of the stream quality factors and derive the optimal streaming bit rates for requests of different classes under various server load conditions. We prove that the optimal allocation, referred to as harmonic proportional allocation, not only maximizes the system utility function, but also guarantees proportional fair sharing between classes with different prespecified differentiation weights. We evaluate the allocation scheme, in combination with two popular request scheduling approaches, via extensive simulations and compare it with an absolute differentiation strategy and a proportional-share strategy tailored from relative differentiation in networking. Simulation results show that the harmonic proportional allocation scheme can meet the objective of relative differentiation in both short and long timescales and greatly enhance the service availability and maintain low queueing delay when the streaming system is highly loaded.     

基于效用的EPON VoD QoS组播实现机制研究

服务质量无法保证和低效益是IP网络上开展VoD业务面临的主要问题.基于组播业务的网络优先级、用户群的SLA优先级和经济优先级,提出了一个基于效用的EPON VoD组播QoS优先级(效用优先级)算法.在网络拥塞的时候,基于该效用优先级来动态调整组播组的资源分配,不但节省了带宽需求和降低包丢失率,而且可通过将网络资源汇聚到高价值的业务上,提高带宽的效益.通过对变长和无序EPON Ethernet下行帧进行基于效用的定长和有序的改进,可减少VoD业务流的包时延抖动.仿真实验结果很好地验证了该机制的优点.     

Friendly web services selection exploiting fuzzy formal concept analysis

This work describes a system for supporting the user in the discovery of semantic web services, taking into account personal requirements and preference. Goal is to model an ad-hoc service request by selecting conceptual terms rather than using strict syntax formats. Through a concept-based navigation mechanism indeed, the user discovers conceptual terminology associated to the web resources and uses it to generate an appropriate service request which syntactical matches the names of input/output specifications. The approach exploits the fuzzy formal concept analysis for modeling concepts and relative relationships elicited from web resources. After the request formulation and submission, the system returns the list of semantic web services that match the user query.     

A resource selection scheme for QoS satisfaction and load balancing in ad hoc grid

Ad hoc grids are highly heterogeneous and dynamic, in which the availability of resources and tasks may change at any time. The paper proposes a utility based resource selection scheme for QoS satisfaction and load balancing in ad hoc grid environments. The proposed scheme intends to maximize the QoS satisfaction of ad hoc grid users and support load balancing of grid resources. For each candidate ad hoc grid resource, the scheme obtains values from the computations of utility function for QoS satisfaction and benefit maximization game for ad hoc grid resource preference. The utility function for QoS satisfaction computes the utility value based on the satisfaction of QoS requirements of the grid user request. The benefit maximization game for grid resource node preference computes the preference value from the resource point of view. Its main goal is to achieve load balancing and decrease the number of resource selection failure. The utility value and the preference value of each candidate ad hoc grid resource are combined to select the most suitable grid resource for ad hoc grid user request. In the simulation, the performance evaluation of proposed algorithm for ad hoc grid is conducted.     

Priority scheduling service for E-commerce web servers

Service scheduling is one of the crucial issues in E-commerce environment. E-commerce web servers often get overloaded as they have to deal with a large number of customers’ requests—for example, browse, search, and pay, in order to make purchases or to get product information from E-commerce web sites. In this paper, we propose a new approach in order to effectively handle high traffic load and to improve web server’s performance. Our solution is to exploit networking techniques and to classify customers’ requests into different classes such that some requests are prioritised over others. We contend that such classification is financially beneficial to E-commerce services as in these services some requests are more valuable than others. For instance, the processing of “browse” request should get less priority than “payment” request as the latter is considered to be more valuable to the service provider. Our approach analyses the arrival process of distinct requests and employs a priority scheduling service at the network nodes that gives preferential treatment to high priority requests. The proposed approach is tested through various experiments which show significant decrease in the response time of high priority requests. This also reduces the probability of dropping high priority requests by a web server and thus enabling service providers to generate more revenue.     

基于SLA波长业务的ASON风险规避算法

为使智能光网络(ASON)在受灾时各等级协定(SLA)波长业务重获局向资源,研究了一种风险规避算法.首先通过构建动态损毁数学模型为不同SLA等级波长业务的连接分别设定稳定度阈值条件.然后借鉴启发式算法计算思想为受灾的各等级SLA波长业务分别制定自愈策略.再根据灾后通路资源需求变化设计带宽重置方案以保证灾后SLA业务的生存性.仿真表明,算法在稳健性、失效率、呼损率多指标中均有良好的优势.     

一个基于自管理单元支持差分服务的Web容器

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.     

A generic architecture for autonomic service and network management

As the Internet evolves into an all-IP communication infrastructure, a key issue to consider is that of creating and managing IP-based services with efficient resource utilization in a scalable, flexible, and automatic way. In this paper, we present the Autonomic Service Architecture (ASA), a uniform framework for automated management of both Internet services and their underlying network resources. ASA ensures the delivery of services according to specific service level agreements (SLAs) between customers and service providers. As an illustrative example, ASA is applied to the management of DiffServ/MPLS networks, where we propose an autonomic bandwidth sharing scheme. With the proposed scheme, the bandwidth allocated for each SLA can be automatically adjusted according to the measured traffic load and under policy control for efficient resource utilization, while SLA compliance over the network is always guaranteed.     

SLA based resource allocation policies in autonomic environments

Nowadays, large service centers provide computational capacity to many customers by sharing a pool of IT resources. The service providers and their customers negotiate utility based Service Level Agreement (SLA) to determine the costs and penalties on the base of the achieved performance level. The system is often based on a multi-tier architecture to serve requests and autonomic techniques have been implemented to manage varying workload conditions. The service provider would like to maximize the SLA revenues, while minimizing its operating costs. The system we consider is based on a centralized network dispatcher which controls the allocation of applications to servers, the request volumes at various servers and the scheduling policy at each server. The dispatcher can also decide to turn ON or OFF servers depending on the system load. This paper designs a resource allocation scheduler for such multi-tier autonomic environments so as to maximize the profits associated with multiple class SLAs. The overall problem is NP-hard. We develop heuristic solutions by implementing a local-search algorithm. Experimental results are presented to demonstrate the benefits of our approach.