Load-balancing data distribution in publish/subscribe mode

To improve data distribution efficiency a load-balancing data distribution LBDD method is proposed in publish/subscribe mode.In the LBDD method subscribers are involved in distribution tasks and data transfers while receiving data themselves.A dissemination tree is constructed among the subscribers based on MD5 where the publisher acts as the root. The proposed method provides bucket construction target selection and path updates furthermore the property of one-way dissemination is proven.That the average out-going degree of a node is 2 is guaranteed with the proposed LBDD.The experiments on data distribution delay data distribution rate and load distribution are conducted. Experimental results show that the LBDD method aids in shaping the task load between the publisher and subscribers and outperforms the point-to-point approach.

Publish-Subscribe系统支付机制研究

已有的 pub- sub系统支付机制尚有许多缺陷 ,无法满足实际需求 .设计了一套新的基于可信任硬件 (安全协处理器、智能卡 )的支付机制 .这套机制具有良好的保密性、匿名性、高效性和公平性 ,而且实现了时间敏感信息的公平交易 .并对基于内容的 pub- sub系统支付问题给出了完整、有效和实用的解决方案 .

An SDN-Based Publish/Subscribe-Enabled Communication Platform for IoT Services

Publish/subscribe paradigm paves a way to integrate and serve many scalable, inter-operable Internet of Things(IoT) applications. The increasing IoT applications require new properties of publish/subscribe communication model, for example, strict quality of service(Qo S) guarantees, supporting a large number of widely distributed devices, etc. Software Defined Networking(SDN) enables personalized programming and individualized QoS supports for different applications. The combination of the two will have a good prospect. In this paper, we present an IoT-oriented communication platform which combines the publish/subscribe paradigm with SDN, aiming at establishing an IoT ecosystem to facilitate IoT services/applications accessing internet. We design the interaction logic of topic-based publish/subscribe middleware, and describe the setup and maintenance of topology information as well as event routing in detail, considering the characteristics of SDN. Finally, we exemplify its practicability with a deployed District Heating Control and Information Service System(DHCISS) and validity the effectiveness with some experiments.

Cross-Layer QoS Enabled SDN-Like Publish/Subscribe Communication Infrastructure for IoT

Publish/subscribe paradigm is often adopted to create the communication infrastructure of the Internet of Things(IoT)for many clients to access enormous real-time sensor data.However,most current publish/subscribe middlewares are based on traditional ossified IP networks,which are difficult to enable Quality of Service(QoS).How to design the next generation publish/subscribe middleware has become an urgent problem.The emerging Software Defined Networking(SDN)provides new opportunities to improve the QoS of publish/subscribe facilities for delivering events in IoT owing to its customized programmability and centralized control.We can encode event topics,priorities and security policies into flow entries of SDN-enabled switches to satisfy personalized QoS needs.In this paper,we propose a cross-layer QoS enabled SDN-like publish/subscribe communication infrastructure,aiming at building an IoT platform to seamlessly connect IoT services with SDN networks and improving the QoS of delivering events.We first present an SDN-like topic-oriented publish/subscribe middleware architecture with a cross-layer QoS control framework.Then we discuss prototype implementation,including topic management,topology maintenance,event routing and policy management.In the end,we use differentiated services and cross-layer access control as cross-layer QoS scenarios to verify the prototype.Experimental results show that our middleware is effective.

Providing Delay-Guaranteed Multicast Transmission Services for an SDN-Based Publish/Subscribe System

Providing end-to-end delay guarantees in traditional Internet is a complex task due to the distributed nature of TCP/IP protocols. Software Defined Networking(SDN) gives a new dimension to improve QoS(Quality of Service) as it can benefit from its flexibility, programmability and centralized view. In this paper, we provide delay-guaranteed data transmission service instead of "best efforts" service for a topic-based publish/subscribe system by means of exploring these specific features of SDN. We attribute this routing problem in such conditions to Delay-Constraint Lowest Cost Steiner Tree(DCLCST) problem. To solve it, we compute the shortest delay paths from source node to every subscribe node and the shortest cost paths from every subscribe node to any other node using dijkstra algorithm. Then we construct a delay-constraint least cost steiner tree for per-topic based on these paths as multicast tree. We also present experimental results to demonstrate the effectiveness of the algorithms and methods we proposed.

Embedding Authentication &Authorization in Discovery Protocols for Standard Based Publish/Subscribe Middleware: A Performance Evaluation

Standard based Pub/Sub middleware, such as OMG Data Distribution Service (DDS), could assume a key role in supporting computer communications requiring continuous state information updating, deterministic deadline to data delivering and real time information adjourning. This kind of capability could be well ex-ploited by Peer-To-Peer (P2P) systems, Internet-wide as long as private ones, like in Public Safety or Civil Protection Communication Systems;but Pub/Sub specifications, and DDS/RTPS (Real Time Publish Sub-scribe) as well, usually do not provide Authentication & Authorization (AA) mechanisms. In the present work two important novelties are assessed: a possible scheme to implement AA in DDS/RTPS networks and a time performance evaluation study about embedded Authentication in RTPS.

A Real-Time-Enabled, Blackboard-Based, Publish/Subscribe Architecture for Wireless Sensor Nodes

Wireless sensor network nodes have only limited resources concerning memory and battery life-time. Mem- ory can be efficiently used by sharing data, and the life-time of a battery can be extended, when the node has long power saving sleep-phases. We propose a publish/subscribe architecture that achieves these two aims. The results of our work are of great interest for sensor application developers, giving them now the opportu- nity to use our architecture for sharing data among different applications on the node as well as the different layers of the operating system. We introduce a blackboard which is used for centrally storing published val- ues, like measured data from a monitored sensor. This makes it possible to share stored data without monitoring the sensors once again, which is advantageously concerning power consumption, memory space, and reaction time. Beside the proposed publish/subscribe method for sensor nodes with its notification possibili- ties, our architecture fulfills also real-time requirements. We show how the well-known sensor operating system MANTIS OS can be extended by a real-time enabled, blackboard-based publish/subscribe architect- ture. This architecture and first of all its implementation is of special interest for cross layer optimization of sensor applications. Cross-layer approaches benefit from our architecture because the available implementa- tion can be used as an efficient framework for central storing and managing of shared values.

Research of Publish and Subscribe Model Based on WS-Notification

WS-Notification bundle of standards, WS-BaseNotification, WS-Topics, and WS-BrokeredNotification, can be used as a general purpose publish/subscribe interface for Service Oriented Architectures. We provide an overview of the WS-Notification specification and describe a modified publish and subscribe model based on WS-Notification. The model is an adaptive policy-driven notification framework that can help enterprises to meet the flexibility and respon-siveness requirements of the enterprise. With the modified publish/subscribe model, information consumers can dy-namically and declaratively create and configure entities on their behalves to manage their distribution requirements.

Connected-Vehicle Data Exchanges and Positioning Computing Based on the Publish-Subscribe Paradigm

Connected vehicles for safety and traffic efficient applications require device-to-device connections supporting one-to-many and many-to-many communication, precise absolute and relative positioning and distributed computing. Currently, the 5.9 GHz Dedicated Short Range Communications (DSRC) and 4G-Long-Term Evolution (LTE) are available for connected vehicle services. But both have limitations in reliability or latency over large scale field operational tests and deployment. This paper proposes the device-to-device (D2D) connectivity framework based on publish-subscribe architecture, with Message Queue Telemetry Transport (MQTT) protocol. With the publish-subscribe communication paradigm, road mobile users can exchange data and information in moderate latency and high reliability manner, having the potential to support many Vehicle to Everything (V2X) applications, including vehicle to vehicle (V2V), vehicle to roadside infrastructure (V2I), and vehicle to bicycle (V2B). The D2D data exchanges also facilitate computing for absolute and relative precise real-time kinematic (RTK) posi-tioning. Vehicular experiments were conducted to evaluate the performance of the proposed publish-subscribe MQTT protocols in term of latency and reliability. The latency of data exchanges is measured by One-trip-time (OTT) and the reliability is measured by the packet loss rate (PLR). Our results show that the latency of GNSS raw data exchanges between vehicles through 4G cellular networks at the rate of 10 Hz and the data rates of 10 kbps are less than 300 ms while the reliability is over 96%. Vehicular positioning experiments have also shown that vehicles can exchange raw GNSS data and complete mov-ing-base RTK positioning with the positioning availability of 98%.

Energy-Efficient Content-Based Routing in Internet of Things

The?convergence of the Internet, sensor networks, and Radio Frequency Identification (RFID) systems has ushered to the concept of Internet of Things (IoT) which is capable of connecting daily things, making them smart through sensing, reasoning, and cooperating with other things. Further, RFID technology enables tracking of an object and assigning it a unique ID. IoT has the potential for a wide range of applications relating to healthcare, environment, transportation, cities… Moreover, the middleware is a basic component in the IoT architecture. It handles heterogeneity issues among IoT devices and provides a common framework for communication. More recently, the interest has focusing on developing publish/subscribe middleware systems for the IoT to allow asynchronous communication between the IoT devices. The scope of our paper is to study routing protocols for publish/subscribe schemes that include content and context-based routing. We propose an Energy-Efficient Content-Based Routing (EECBR) protocol for the IoT that minimizes the energy consumption. The proposed algorithm makes use of a virtual topology that is constructed in a centralized manner and then routes the events from the publishers to the intended interested subscribers in a distributed manner. EECBR has been simulated using Omnet++. The simulation results show that EECBR has a significant performance in term of the energy variance compared to the other schemes.

面向航天器大数据安全传输的发布/订阅系统设计

针对航天器试验任务过程监控的在轨故障诊断状态检测、健康状态评估与航天器寿命预测等多个环节中,海量试验数据在传输、共享、处理、分析、存储等过程中面临的巨大压力,构建面向航天器多源异构数据管理的分布式大数据发布/订阅系统(big-data publish/subscribe system,BPSS)框架。借助大数据与云平台技术,设计了一套航天器海量在轨试验数据传输、管理与缓存方案,对云节点实现主从调控与弹性扩容,并通过基于消息一致性的动态选举算法完成大规模发布/订阅任务,保证数据传输的安全性、一致性与计算效率,具备大数据订阅响应迅速、多源异构数据高吞吐稳定性、分布式组件部署灵活等优点。实地航天器数管实验结果表明,BPSS数据订阅的平均响应时延为0.05 s/GB,同时在单日吞吐量达到85 GB量级时,数据丢帧率控制在0.025%、数据破损率控制在0.018%,与其他开源的发布/订阅系统相比具备一定竞争力。

基于时序数据库与发布订阅机制的环境试验数据处理平台

针对航天领域技术进步及型号任务激增导致的环境试验数据种类与规模庞大、数据源分散,数据处理软件开发耗时且风格不统一,因而不同型号之间环境试验数据难以统一管理、数据处理功能分散的问题,开发了基于时序数据库与发布订阅机制的环境试验数据处理平台。该平台利用时序数据库对分散的海量环境试验数据进行统一存储与管理,实现了大规模数据的高效写入与访问;通过发布订阅机制实现了实时数据的快速展示;通过综合汇总不同型号对数据处理的需求,实现了环境试验数据通用化解析、数据处理与判读、文本导出和报告生成等多种业务功能。最后对环境试验数据处理平台的实施效果进行展示,证明了其具备良好的工程实用性。

Mort:面向实时数据分发和传输优化的依赖性任务卸载框架

在边缘协同计算中,单一设备已无法满足大量复杂任务对系统高计算能力和低时延的需求,通常需要将任务卸载到邻近具有丰富计算存储资源的边缘服务器上,同时,通过发布订阅模式构建统一的通信协议,支撑任务对数据共享和隐私保护的需求.在发布订阅系统中,任务往往具有依赖性、执行周期性和高频率数据分发等特性,而传统的任务卸载算法主要针对数据单次传输和任务单次执行的场景,无法有效应对发布订阅系统中的任务卸载问题.因此,设计一个任务卸载及管理框架Mort.该框架使用基于静态代码分析的任务分解方法解构任务之间的依赖性,支撑任务并行;采用基于非线性整数规划建模和基于分组及资源融合的卸载算法,优化网络数据传输;采用基于协程的调度模型调度卸载后的任务,减少任务调度开销.大量的仿真实验和真实场景实验表明,Mort的数据传输优化能达到最优解的80%~90%,且引入的系统开销仅约为2%.

基于发布订阅机制的实时消息系统设计与实现

基于ApacheKafka消息代理框架使用成本高和基于私有协议导致的兼容性不好等问题,提出了以WebSocket作为通信协议的发布订阅机制实时消息系统的设计方案。以聊天系统为例,使用Socket.IO实现后端服务,使用Redis的发布订阅机制来构建实时消息系统,同时提出了全局ID、消息令牌等模块的设计思路。首先进行了方案技术选型,具体包括消息传递模型与协议选型、后端框架选型,然后阐述了系统架构设计和主要模块实现,最后进行了系统测试。测试结果表明系统运行稳定,实时连接性能良好。

等离子体控制系统用户界面与参数管理

等离子体控制系统是聚变实验中重要的系统之一,用于对等离子体的各项参数进行实时的反馈控制.目前自主研发的等离子体控制系统基于组件模型开发,其核心控制功能通过算法组件执行各种等离子体控制算法来实现,需要提供图形界面编辑算法的预设参数,并对参数进行管理,因此基于PyQt5实现图形界面,并开发参数配置组件负责参数存储回调,通过发布订阅通讯机制完成两者的数据传输.采用可扩展标记语言定义控制算法预设参数信息使得用户界面与控制算法解耦,通过接口描述语言统一定义参数数据结构,设计MySQL数据库存储历史参数数据,并基于发布/订阅通讯机制完成数据通讯.

STRS系统异构处理器通信中间件的设计与实现

针对空间通信无线电系统(STRS)异构处理器间通信存在的实时性不高、冗余度较大、无法故障恢复等问题,将分布式数据分发服务(DDS)中间件技术引入到STRS架构中,实现STRS异构处理器波形应用组件之间基于发布/订阅模式的通信中间件。在完全兼容STRS标准规范的前提下,有效地提高了基于STRS的通信系统消息传递的实时性,降低了系统的复杂度和冗余度,提高了开发效率,节省了系统的开发和维护成本,实现了全局和局部模块的动态重构。

EAST实验数据发布与信息交流系统设计

EAST实验过程中会产生大量数据,包括参数配置信息、实时诊断与控制数据、日志数据等,是实验人员和物理学者分析和交流实验进展的基础。为提供便捷高效的数据访问平台,设计并实现了基于移动端的EAST实验数据发布与信息交流系统。系统通信部分通过集成第三方通信SDK,实现了全功能即时通信;实验数据发布部分由参数订阅、EPICS状态参数发布、MDSplus信号发布和PCS日志发布4个功能模块组成,基于Redis发布订阅模型设计实现,首次将分布式技术引入EAST实验数据发布领域。实际应用效果显示,该系统基本能帮助实验人员和物理学者实现实时获取实验数据和实时交流。

战术服务集成支撑架构

战术环境面临着通信链路弱连接以及网络拓扑动态多变等问题,导致基于区域云中心的服务框架无法适应复杂的战术环境。由于服务集成平台向上可承接区域中心、向下可铰链战术末端,并具有中心-边缘-末端的信息共享能力,因此可构建适应窄带环境的服务集成平台。研究了窄带服务自适应实现方法,提出了战术战役一体模式下服务协议转换总线技术机制,解决了请求/响应和订阅/发布2种通信模型下的服务互操作问题。

面向发布-订阅系统的多级安全访问控制方案

当前的访问控制方案难以满足发布-订阅系统的多级安全需求.一方面存在高安全级数据泄露给低安全级订阅者的风险;另一方面,由于密钥总数随着用户数的增长而迅速增加,密钥管理面临更大的挑战.为此,本文提出了一个面向发布-订阅系统的多级安全访问控制方案.首先,结合EMDK和HKAS设计了多级密钥分配机制,基于该机制实现了对发布数据的多级安全访问控制以及灵活且可扩展的密钥管理.其次,采用签密算法批量分发同一安全级的授权信息和加密密钥,保证安全性的同时提高分发效率.最后,对所提出的方案进行安全性和性能分析,结果表明所提方案能够实现静态敌手下的密钥不可区分性,并且有效降低了密钥分发的计算开销.