面向电子政务的发布订阅中间件设计与实现

目前紧耦合通信模式已经不能满足大规模电子政务应用发展的需求,迫切需要一种新的松耦合信息交互基础设施,而发布订阅中间件是解决该问题的有效技术。基于客户/网络体系结构,提出一种发布订阅中间件系统Xinfo,设计其总体框架和关键组成部分,给出面向代理网络的消息路由算法。实际部署测试结果表明,Xinfo系统能够解决大规模电子政务系统间的松耦合信息交互问题。     

一种基于sFlow的网络流量分析方法

摘要：随着网络应用越来越广泛,关键的企业应用对网络的依赖性也越来越强,在网络使用上的一些很小的变化都有可能对网络的性能和可靠性造成很大的影响。因此,进行全方位、高速、实时的网络流量分析及网络性能分析成为一项有挑战性的、具有重要意义的研究课题。先前的流量监测技术（如RMON、NetFlow技术）都有许多缺点,而唯有ssFlow技术能够“看透”当今高速、复杂的网络。通过sFlow技术可以采集不同类别的大量的原始信息,但仅仅拥有这些原始信息还远远不够,还需要对这些原始信息进行分析析,从而得出对网络管理者有用的性能信息。本文提出了一种对利用sFlow技术采样的原始数据进行流量分析的方法,并给出了一个基于sF]ow的网络流量分析系统架构。     

A token-bucket based notification traffic control mechanism for IMS presence service

Presence is a service that allows a user to be informed about the specified state of another user. Presence service has become a key enabler for next-generation applications such as instant messaging, push-to-talk and web2.0. However, recent studies show that the notification traffic of presence service causes heavy signaling load on IP multimedia subsystem (IMS) network. This paper introduced a token-bucket based notification traffic control (TNTC) mechanism, which is an application layer solution deployed at the presence server. The TNTC aims at upgrading valid access probability while controlling the notification traffic. A mathematical model of a queuing system is proposed to describe TNTC. We analyzed its main probability features and investigated the effects of different parameters on the performance of TNTC. Extensive simulations verified that TNTC can effectively control notification traffic and perform better than the existing schemes in terms of valid access probability and update arrival rate.     

商务智能中元数据管理模型研究

随着数据仓库技术应用的不断深入,商务智能或者说数据仓库系统构成越来越复杂,所依托的信息系统也愈加多样、异质。我们知道,对这些来源多样的信息进行整合以提供商务分析,合理利用元数据是其关键。元数据管理在商务智能领域非常重要,特别对来自不同厂商的数据集成来说尤为关键,因大部分的商务智能应用都非常依赖元数据的构建。本文阐述了商务智能中元数据管理的各个部分,并详细分析了被OMG（对象管理小组）接受的公共仓库模型——CWM。同时,给出了CWM中元数据存储和管理的可能实现方式。     

多服务交换资源虚拟分割算法的研究

为用户或应用提供多样性服务是网络发展的趋势，不同的服务需要相应的网络转发或交换机制支持，实现多服务交换或转发的关键是资源分配和管理，该文提出一种支持面向应用的多服务交换路由器的资源虚拟分割算法，它结合可编程路由器，根据不同应用的转发需求，为不同转发服务分配一定范围的虚拟资源区间，该虚拟分割区间能够隔离和保护不同应用网络流，为其提供一定的服务质量保障，并使服务间能够可控，动态地共享多余的资源。     

Policy-based Diffserv on Internet servers: the AIX approach

The Internet infrastructure must evolve from best-effort service to meet the needs of different customers and applications. With Internet traffic differentiation, service providers can support a range of offerings, such as loss or delay bounds and network bandwidth allocation, to meet different performance requirements. The differentiated services (Diffserv) architecture provides a scalable approach, in which network access (or edge) devices aggregate traffic flows onto provisioned pipes that traverse a streamlined network core. We have identified the key requirements for provisioning Diffserv functions on Internet servers. Based on these requirements, we have implemented, and deployed, a policy-based architecture on IBM's AIX operating system that provides Diffserv services to both QoS-aware and -unaware applications     

Traffic control for freeway networks with sustainability-related objectives: Review and future challenges

Sustainability is a key point in the design and management of mobility and traffic systems, which affects also the development of traffic control strategies for freeway networks. According to sustainability-related concepts, freeway traffic controllers should be devised not only for maximally exploiting the road capacity and decreasing vehicles travel delays, but also for reducing pollutant emissions, fuel consumptions, accidents, noise, and so on. This paper analyses the state of the art of freeway traffic control strategies characterised by sustainability-related objectives, in particular referred to traffic emissions and traffic safety, by providing a classification of the research papers in this area. The final part of the paper highlights the main research challenges for modelling and control techniques brought by the introduction of emerging information and communication technologies, that are becoming more and more widespread and are transforming the concept of vehicles in intelligent and connected agents, able to measure the traffic state and to implement specific traffic control policies.     

基于订阅/发布服务的广域信息管理系统应急响应机制

广域信息管理系统(SWIM)是一个分布式的大型网络系统,它实时地向空中交通管理部门、航空机场和航空公司等提供不间断的航空信息数据共享和传输服务。为了保障SWIM服务的连续性,研究了基于订阅/发布服务的SWIM系统应急响应机制。首先,根据实时监测SWIM网络的各性能指标,提出了基于改进的模糊层次分析的网络可生存性评估方法;其次,当SWIM网络生存性指标下降到低于参量的边界值时,发布相应信息到订阅者,由订阅者确定是否进行服务漂移;最后,分别针对自然灾害和分布式拒绝服务(DDoS)攻击两种情况,提出了基于订阅/发布服务的SWIM应急响应模型(ERMSP),该模型以订阅发布和信任管理机制为基础。仿真实验结果表明,通过对网络性能各指标的实时监测和部署ERMSP,可抵抗性提高了8.9%,业务连续性提高了18.2%,可以实现SWIM的应急响应。     

基于手机定位的动态行程时间探测

动态交通信息的发布与预测是ITS的关键所在。然而由于在各种外部因素下,道路交通状态呈现出随机变化的特性使得动态交通信息的发布与预测成为一大难点。行程时间和车速的发布与预测是实时动态交通发布与预测的重要指标,也是交通流诱导系统理论研究项目的一个重要环节。所以,这就使动态行程时间的探测这一课题显得尤为重要。结合某城市的实际情况,文中探讨并实践了一种全新的基于手机定位的动态行程时间探测方法,并对其技术路线、关键问题以及难点问题进行一一论述。该方法的最大优势:城市范围内除需要安装几块探测卡以外,几乎无需任何其他投入,从而省去了利用其他技术所需要的巨额安装与维护费用,这一点对像我国这样的发展中国家具有重大的意义。另外,该技术还有安装快、报告的信息遍及整个路网,而不是仅限于预定地点的特点。     

Network aware dynamic context subscription management

Context-awareness is a key requirement in many of today’s networks, services and applications. Context management systems are used to provide access to distributed, dynamic context information. The reliability of remotely accessed dynamic context information is impacted by network delay, packet drop probability, its information dynamics and the access strategy used. Due to the characteristics of the different access strategies, different levels of reliability of context information can be ensured, but at the same time, these strategies lead to different access traffic which impacts also the network performance, and hence feeds back to the reliability of the information. Furthermore, different levels of QoS may be available and used in order to mitigate the impact of network performance degradation on the reliability of the dynamic context information. In this paper we describe a system and algorithms that are capable of configuring effectively context access strategies in order to maximize reliability of all accessed dynamic context information. The framework utilizes and extends existing information reliability models, and it can utilize different network performance models. Simulation results of scenarios in which the framework uses finite-buffer bottleneck performance models demonstrate the effectiveness of our algorithm to increase reliability. Furthermore, the framework is applied to a scenario with QoS classes that allows to trade off delay and loss via different buffer-size configurations.     

安全服务管理层(CSSM)的功能和实现

通用数据安全框架CDSA（Common Data Security Architecture)是一个多层的安全平台，它向应用程序提供动态和全面的安全服务。安全服务管理层CSSM（Common Security Services Manager)是CDSA中最关键的一层，CSSM通过不同类别的组件管理器管理着不同类别的安全服务提供组件。本文将着重探讨在WINDOWS环境中利用COM＋技术实现CSSM的基本功能。     

面向智慧交通的图像处理与边缘计算

随着全球人口的持续增长和城市化进程的加速,道路拥挤、交通事故和污染排放增加等问题日益严重。智慧交通系统旨在借助先进的信息与通信技术建成高效安全、环保舒适的交通与运输体系,提供全方位的交通信息服务和安全高效、经济快捷的交通运输与出行服务。经过各国多年来的竭力推进与发展,智慧交通系统在交通管理、自动驾驶与车路协同等方向均得到广泛的应用。智慧交通的发展离不开通信、计算机与控制等研究方向的突破与创新。其中,图像处理作为智慧交通系统的核心技术之一,它的研究进展直接影响着智慧交通系统的部署。图像处理技术是指计算机对图像进行增强、复原、提取特征、分类和分割等技术处理,通过对交通视觉图像的处理,为智慧交通系统的感知、识别、检测、跟踪和路径规划等功能提供了最直接与重要的信息。此外,面对智慧交通系统所产生的大量数据计算任务,边缘计算技术则将中心云服务下沉至各边缘节点附近,不但能够优化算力负载分配,还能够满足智慧交通应用与服务对低时延、高响应速度的需求。本文从智慧交通系统的发展现状入手,分别围绕面向智慧交通的图像处理与边缘计算技术,阐述其研究热点与前沿进展,汇总与比较国内外的相关学术和产业成果,并对智慧交通...     

Geospatial information infrastructures to address spatial needs in health: Collaboration,challenges and opportunities

Most health-related issues such as public health outbreaks and epidemiological threats are better understood from a spatial–temporal perspective and, clearly demand related geospatial datasets and services so that decision makers may jointly make informed decisions and coordinate response plans. Although current health applications support a kind of geospatial features, these are still disconnected from the wide range of geospatial services and datasets that geospatial information infrastructures may bring into health. In this paper we are questioning the hypothesis whether geospatial information infrastructures, in terms of standards-based geospatial services, technologies, and data models as operational assets already in place, can be exploited by health applications for which the geospatial dimension is of great importance. This may be certainly addressed by defining better collaboration strategies to uncover and promote geospatial assets to the health community. We discuss the value of collaboration, as well as the opportunities that geographic information infrastructures offer to address geospatial challenges in health applications.     

基于令牌桶的分级动态流量整形算法

区分服务和流量整形是保证实时应用和关键应用得到相应QoS的重要技术。提出基于二级令牌分配机制的流量整形结构,逐级设计令牌分配的具体算法。该算法使区分服务网络中优先级较高的数据流获得更多的出口带宽资源,同时根据输出需求动态调整同优先级数据流的带宽资源,兼顾优先和公平,提高企业网络出口有限带宽的使用效益。     

基于手机RFSIM与北斗GIS城市实时交通动态导航平台

目前,从智能交通系统的发展（ITS）来看,国内大多数导航系统为静态导航,缺乏根据实时交通信息进行动态导航的功能.从而提出一种基于手机RFSIM与GIS技术结合的城市实时交通动态导航平台,为出行者提供实时动态的交通信息和导航服务.该系统主要包括实时交通信息采集系统,短时交通预测系统,北斗或GPS定位以及GIS实时导航系统.在已获得的相关技术的支撑下,着力解决在此导航系统中涉及到的交通信息的获取、北斗定位和实时交通动态导航中的关键技术问题,并进行可行性分析.     

基于JMS的消息服务的研究与开发

为了解决企业应用程序间消息服务的异步通信等需求和考虑到面向消息的中间件在企业级应用中的使用越来越广泛的情况，对J2EE架构中基于EJB2.0的JAVA消息服务和Message-Driven Bean的原理和实现方法进行了研究，较详尽地介绍了JMS的异步消息处理技术，并结合“点到点”和“发布／订阅”两种消息通信模式，论述了电子商务中的拍卖系统的具体实现。从中可以看出JMS的使用让该系统更加灵活和易扩展。     

The probability relationship between video’s instantaneous and average aggregate rates

The growing demand for video applications and services has contributed substantially to the increase of video traffic on the Internet. Measurement-based admission control was proposed with the primary aim of eliminating or reducing the need of flow state information; also to control overhead for admission decision and maximize utilization at the potential cost of QoS degradation. Some of the admission algorithms depend on the instantaneous rate for its operation. On the other hand, the average aggregate rate has been proposed to better suit variable rate such as video traffic. In this paper, we investigate the probability relationship between the instantaneous and average aggregate rates for video traffic. A mathematical model has been developed to quantify the probability relationship between both rates and validated through extensive simulations using real video sequences. The average rate was found to be lower than instantaneous for a small number of flows, however there was no pronounced difference for a large number of flows. Furthermore, the difference between both rates increases for fast moving content such as sport or longer measurement time window.     

A comprehensive review on blockchains for Internet of Vehicles: Challenges and directions

Internet of Vehicles (IoVs) consists of smart vehicles, Autonomous Vehicles (AVs) as well as roadside units (RSUs) that communicate wirelessly to provide enhanced transportation services such as improved traffic efficiency and reduced traffic congestion and accidents. Unfortunately, current IoV networks suffer from security, privacy, and trust issues. Blockchain technology emerged as a decentralized approach for enhanced security without depending on trusted third parties to run services. Blockchain offers the benefits of trustworthiness and immutability and mitigates the problem of a single point of failure and other attacks. In this work, we present the state-of-the-art Blockchain-enabled IoVs (BIoVs) with a particular focus on their applications, such as crowdsourcing-based applications, energy trading, traffic congestion reduction, collision, accident avoidance, infotainment, and content caching. We also present in-depth applications of federated learning (FL) for BIoVs. The key challenges of integrating Blockchain with IoV are investigated in several domains, such as edge computing, machine learning, and Federated Learning (FL). Lastly, we present several open issues, challenges, and future opportunities in AI-enabled BIoV, hardware-assisted security for BIoV, and quantum computing attacks on BIoV applications.