Cloud can be defined as a new computing paradigm that provides scalable, on-demand, and virtualized resources for users. In this style of computing, users can access a shared pool of computing resources which are prov...Cloud can be defined as a new computing paradigm that provides scalable, on-demand, and virtualized resources for users. In this style of computing, users can access a shared pool of computing resources which are provisioned with minimal management efforts of users. Yet there are some obstacles and concerns about the use of clouds. Guaranteeing quality of service(Qo S) by service providers can be regarded as one of the main concerns for companies tending to use it. Service provisioning in clouds is based on service level agreements representing a contract negotiated between users and providers. According to this contract, if a provider cannot satisfy its agreed application requirements, it should pay penalties as compensation. In this paper, we intend to carry out a comprehensive survey on the models proposed in literature with respect to the implementation principles to address the QoS guarantee issue.展开更多
数字电视信号对传输质量有着十分严苛的要求,传统网际互连协议(Internet Protocol,IP)网络在提供端到端服务质量(Quality of Service,QoS)保障方面仍面临诸多挑战。对此,分析数字电视信号的业务特点和传输需求,梳理IP网络QoS领域的发展...数字电视信号对传输质量有着十分严苛的要求,传统网际互连协议(Internet Protocol,IP)网络在提供端到端服务质量(Quality of Service,QoS)保障方面仍面临诸多挑战。对此,分析数字电视信号的业务特点和传输需求,梳理IP网络QoS领域的发展脉络,提出一种端到端QoS保障解决方案的总体架构,从接入网、骨干网、综合管理平台三个层面给出优化措施。展开更多
The MAC layer in IEEE802.16 is designed to differentiate service among traffic categories with different multimedia requirements.In this paper,a scheduling algorithm at MAC layer for multiple connections with diverse ...The MAC layer in IEEE802.16 is designed to differentiate service among traffic categories with different multimedia requirements.In this paper,a scheduling algorithm at MAC layer for multiple connections with diverse QoS requirements is proposed.As for this algorithm,each connection is assigned a priority,which is updated dynamically based on its service status concluding queue characteristic and channel state.A connection with the highest priority is scheduled each time.Analytical model is developed by assuming a Finite State Markov Chain(FSMC)channel model.Simulation results show that the proposed scheduling algorithm can improve the performance of mean waiting time and throughput in broadband wireless networks.展开更多
在网络世界中,网际互连协议(Internet Protocol,IP)承载网扮演着信息流动的骨干角色,其运行表现和服务水准至关重要。文章详细探讨了IP承载网中服务质量(Quality of Service,QoS)策略的设计与优化方法,重点涵盖分类服务与标记、流量控...在网络世界中,网际互连协议(Internet Protocol,IP)承载网扮演着信息流动的骨干角色,其运行表现和服务水准至关重要。文章详细探讨了IP承载网中服务质量(Quality of Service,QoS)策略的设计与优化方法,重点涵盖分类服务与标记、流量控制与优先级队列管理以及链路和节点策略的具体实现。通过流量分析与预测、智能资源分配与调度、动态策略调整以及故障检测与容错机制,提出一系列提升网络性能和用户体验的有效措施。展开更多
Web Service是目前研究界和产业界广泛关注的技术之一.随着Web Service的广泛应用,研究者们普遍认识到,服务的非功能属性,即服务质量(Quality of Service,QoS)是面向服务的应用能否成功的关键因素之一.因此,研究者们尝试从多个角度对Qo...Web Service是目前研究界和产业界广泛关注的技术之一.随着Web Service的广泛应用,研究者们普遍认识到,服务的非功能属性,即服务质量(Quality of Service,QoS)是面向服务的应用能否成功的关键因素之一.因此,研究者们尝试从多个角度对QoS相关问题展开了研究.然而,现有工作普遍关注基于QoS的动态服务选择和组装等上层应用技术,而对于如何获取、存储、度量QoS等基础支持技术研究较少,而这些基础性工作对QoS相关的研究工作具有显著的重要性.此外,不同应用领域对Web Service QoS的需求不尽相同,因此,需要有一套灵活的机制支持在QoS模型定义、QoS度量方法、QoS信息采集等方面体现出的领域特性.针对这个问题,文中提出了一个可扩展的Web Service QoS信息管理框架,详细分析了该框架涉及到的重要方法与核心技术,并给出了该框架在北京大学软件构件库系统中的设计决策和方案.最后,介绍了文中框架在一个863计划项目中的应用实例,该实例展示了用户根据其应用的领域需求对本框架进行扩展并进行Web Service QoS管理的方法,从而验证了本管理框架的可扩展性及实用性.展开更多
网络技术的发展和多接入边缘计算的兴起使得计算和网络资源的部署逐渐靠近终端.随着服务数量的增多,为了向用户更好地推荐服务,如何在复杂、动态的边缘计算环境中实时、准确地预测服务质量(quality of service,QoS)成为一项挑战.本文提...网络技术的发展和多接入边缘计算的兴起使得计算和网络资源的部署逐渐靠近终端.随着服务数量的增多,为了向用户更好地推荐服务,如何在复杂、动态的边缘计算环境中实时、准确地预测服务质量(quality of service,QoS)成为一项挑战.本文提出一种基于服务负载实时预测QoS的深度神经模型(QPSL),它可以为边缘计算中的QoS预测提供缺少的负载状况感知和周期感知.首先,对服务的负载状况进行特征表示,并通过时序分解模块获取时序特征.其次,将CNN和BiLSTM结合,学习潜在的时序关系,生成不同时刻的状态向量.然后,基于Attention机制为历史时刻的状态向量分配权重,从而构造未来时刻的状态向量.最后,将上下文嵌入向量与状态向量送入感知层完成实时QoS预测.基于真实的融合数据集进行了大量的实验,结果表明QPSL在响应时间和吞吐量任务上的MAE分别平均提升了10.28%和10.87%,优于现有的时间感知QoS预测方法.展开更多
Cloud computing can be realized by service interoperation and its essence is to provide cloud services through network. The development of effective methods to assure the trustworthiness of service interoperation in c...Cloud computing can be realized by service interoperation and its essence is to provide cloud services through network. The development of effective methods to assure the trustworthiness of service interoperation in cloud environment is a very important problem. The essence of cloud security is trust and trust management. Combining quality of service （QoS） with trust model, this paper constructs a QoS-aware and quantitative trust-model that consists of initial trust value, direct trust value, and recommendatory trust value of service, making the provision, discovery, and aggregation of cloud services trustworthy. Hence, it can assure trustworthiness of service interoperation between users and services or among services in cloud environment. At the same time, based on this model, service discovery method based on QoS-aware and quantitative trust-model （TQoS-WSD） is proposed, which makes a solid trust relationship among service requestor, service provider and service recommender, and users can find trustworthy service whose total evaluation value is higher. Corapared to QoS-based service discovery （QoS-WSD） method, it is proved by the experiment for TQoS-WSD method that more accurate result of service discovery will be achieved by service requestor, while reasonable time cost is increased. Meanwhile, TQoS-WSD method strongly resists the effect of service discovery by untrustworthy QoS values and improves service invocation success-rate and thus assures trustworthiness of services interoperation.展开更多
The non-functional QoS (quality of service) information helps us to select a proper Web-service from the web applications, by using component services such as UDDI[1](Universal Description, Discovery, and Integration)...The non-functional QoS (quality of service) information helps us to select a proper Web-service from the web applications, by using component services such as UDDI[1](Universal Description, Discovery, and Integration) and MDS(Monitoring and Discovery System). MDS is a suite of web services to monitor and discover resources and service on Grids, but MDS only based on function aspects. This paper studies on an approach to provide the QoS information and a discovery model by using MDS and gives a system deployment and implementation plan. The simulation results show that the method is effective in service discovery.展开更多
基金supported by Fundo para o Desenvolvimento das Ciencias e da Tecnologia(FDCT)(119/2014/A3)
文摘Cloud can be defined as a new computing paradigm that provides scalable, on-demand, and virtualized resources for users. In this style of computing, users can access a shared pool of computing resources which are provisioned with minimal management efforts of users. Yet there are some obstacles and concerns about the use of clouds. Guaranteeing quality of service(Qo S) by service providers can be regarded as one of the main concerns for companies tending to use it. Service provisioning in clouds is based on service level agreements representing a contract negotiated between users and providers. According to this contract, if a provider cannot satisfy its agreed application requirements, it should pay penalties as compensation. In this paper, we intend to carry out a comprehensive survey on the models proposed in literature with respect to the implementation principles to address the QoS guarantee issue.
文摘数字电视信号对传输质量有着十分严苛的要求,传统网际互连协议(Internet Protocol,IP)网络在提供端到端服务质量(Quality of Service,QoS)保障方面仍面临诸多挑战。对此,分析数字电视信号的业务特点和传输需求,梳理IP网络QoS领域的发展脉络,提出一种端到端QoS保障解决方案的总体架构,从接入网、骨干网、综合管理平台三个层面给出优化措施。
文摘The MAC layer in IEEE802.16 is designed to differentiate service among traffic categories with different multimedia requirements.In this paper,a scheduling algorithm at MAC layer for multiple connections with diverse QoS requirements is proposed.As for this algorithm,each connection is assigned a priority,which is updated dynamically based on its service status concluding queue characteristic and channel state.A connection with the highest priority is scheduled each time.Analytical model is developed by assuming a Finite State Markov Chain(FSMC)channel model.Simulation results show that the proposed scheduling algorithm can improve the performance of mean waiting time and throughput in broadband wireless networks.
文摘在网络世界中,网际互连协议(Internet Protocol,IP)承载网扮演着信息流动的骨干角色,其运行表现和服务水准至关重要。文章详细探讨了IP承载网中服务质量(Quality of Service,QoS)策略的设计与优化方法,重点涵盖分类服务与标记、流量控制与优先级队列管理以及链路和节点策略的具体实现。通过流量分析与预测、智能资源分配与调度、动态策略调整以及故障检测与容错机制,提出一系列提升网络性能和用户体验的有效措施。
文摘Web Service是目前研究界和产业界广泛关注的技术之一.随着Web Service的广泛应用,研究者们普遍认识到,服务的非功能属性,即服务质量(Quality of Service,QoS)是面向服务的应用能否成功的关键因素之一.因此,研究者们尝试从多个角度对QoS相关问题展开了研究.然而,现有工作普遍关注基于QoS的动态服务选择和组装等上层应用技术,而对于如何获取、存储、度量QoS等基础支持技术研究较少,而这些基础性工作对QoS相关的研究工作具有显著的重要性.此外,不同应用领域对Web Service QoS的需求不尽相同,因此,需要有一套灵活的机制支持在QoS模型定义、QoS度量方法、QoS信息采集等方面体现出的领域特性.针对这个问题,文中提出了一个可扩展的Web Service QoS信息管理框架,详细分析了该框架涉及到的重要方法与核心技术,并给出了该框架在北京大学软件构件库系统中的设计决策和方案.最后,介绍了文中框架在一个863计划项目中的应用实例,该实例展示了用户根据其应用的领域需求对本框架进行扩展并进行Web Service QoS管理的方法,从而验证了本管理框架的可扩展性及实用性.
文摘通过网络提供服务的Web Service的服务质量会随着网络环境、服务器负载等因素的变化而变化,如何更好地帮助用户选择在未来一段时间内符合服务质量需求的Web Service,是目前服务计算领域中需要解决的关键问题之一。针对上述问题,提出了一种基于时间序列分析的Web Service QoS预测方法,并实现了相应的Web Service QoS自动预测工具。该工具能够根据Web Service的历史QoS数据,有效地预测未来短期内的QoS信息。以17832个Web Service的历史数据为基础,设计了相关实验,并验证了方法的有效性。
基金The National Science and Technology Major Project(No.2012ZX03004005-003)the National Natural Science Foundationof China(No.61171081,61201175)the Science and Technology Support Program of Jiangsu Province(No.BE2011187)
文摘网络技术的发展和多接入边缘计算的兴起使得计算和网络资源的部署逐渐靠近终端.随着服务数量的增多,为了向用户更好地推荐服务,如何在复杂、动态的边缘计算环境中实时、准确地预测服务质量(quality of service,QoS)成为一项挑战.本文提出一种基于服务负载实时预测QoS的深度神经模型(QPSL),它可以为边缘计算中的QoS预测提供缺少的负载状况感知和周期感知.首先,对服务的负载状况进行特征表示,并通过时序分解模块获取时序特征.其次,将CNN和BiLSTM结合,学习潜在的时序关系,生成不同时刻的状态向量.然后,基于Attention机制为历史时刻的状态向量分配权重,从而构造未来时刻的状态向量.最后,将上下文嵌入向量与状态向量送入感知层完成实时QoS预测.基于真实的融合数据集进行了大量的实验,结果表明QPSL在响应时间和吞吐量任务上的MAE分别平均提升了10.28%和10.87%,优于现有的时间感知QoS预测方法.
基金supported by National Basic Research Program of China (973 Program) (No. 2007CB310801)National Natural Science Foundation of China (No. 60873083, No. 60803025, No. 60970017, No. 60903034, No. 60873225)+3 种基金Natural Science Foundation of Hubei Province for Distinguished Young Scholars (No. 2008CDB351)Natural Science Foundation of Hubei Province (No. 2008ABA358, No. 2008ABA379)Research Fund for the Doctoral Program of Higher Education of China (No. 20070486065)Open Foundation of State Key Laboratory of Software Engineering (No. SKLSE20080718)
文摘Cloud computing can be realized by service interoperation and its essence is to provide cloud services through network. The development of effective methods to assure the trustworthiness of service interoperation in cloud environment is a very important problem. The essence of cloud security is trust and trust management. Combining quality of service （QoS） with trust model, this paper constructs a QoS-aware and quantitative trust-model that consists of initial trust value, direct trust value, and recommendatory trust value of service, making the provision, discovery, and aggregation of cloud services trustworthy. Hence, it can assure trustworthiness of service interoperation between users and services or among services in cloud environment. At the same time, based on this model, service discovery method based on QoS-aware and quantitative trust-model （TQoS-WSD） is proposed, which makes a solid trust relationship among service requestor, service provider and service recommender, and users can find trustworthy service whose total evaluation value is higher. Corapared to QoS-based service discovery （QoS-WSD） method, it is proved by the experiment for TQoS-WSD method that more accurate result of service discovery will be achieved by service requestor, while reasonable time cost is increased. Meanwhile, TQoS-WSD method strongly resists the effect of service discovery by untrustworthy QoS values and improves service invocation success-rate and thus assures trustworthiness of services interoperation.
文摘The non-functional QoS (quality of service) information helps us to select a proper Web-service from the web applications, by using component services such as UDDI[1](Universal Description, Discovery, and Integration) and MDS(Monitoring and Discovery System). MDS is a suite of web services to monitor and discover resources and service on Grids, but MDS only based on function aspects. This paper studies on an approach to provide the QoS information and a discovery model by using MDS and gives a system deployment and implementation plan. The simulation results show that the method is effective in service discovery.
