可配置可扩展发布订阅系统的研究及其实现*

分析了当前发布订阅系统的主要类型和存在的问题.基于发布订阅系统的主要设计模型,采用分层与插件相结合的动态体系结构设计方法,设计和实现了可配置和可扩展的发布订阅系统ACT-PS(ACT-Publish/Subscribe System),支持基于应用需求的配置和扩展.在具体的电子政务数据交换系统当中的配置运行表明,ACT-PS系统为通过可配置和可扩展的方式建立发布订阅系统提供了新的途径.     

支持移动推送的一种分层式体系结构

移动环境中依赖内容发送的信息服务越来越受到欢迎，本文探讨了有代表性的应用情况，分析了移动推送服务的特征并提出了一种体系结构，该体系结构基于发布／订阅方式，支持松散耦合实体之间的多对多交互。     

发布/订阅范型中信息投递的服务质量保证

发布/订阅范型中信息可靠投递是保证系统服务质量的关键,现有研究对此考虑不充分。以发布/订阅范型在时间维度上解耦导致的信息投递不确定性为出发点,采用时序分析方法,研究信息投递服务质量的保障措施。在定义投递信息可靠性的基础上,探讨了订阅活跃期、订阅延迟、发布传播延迟对信息投递服务质量的影响,给出了保证服务质量的分布式通知服务的活性性质,并设计了一种提供服务质量保证的发布/订阅代理。分析结果表明,文中给出的计算性质是保障信息投递服务质量的必要条件,信息投递服务质量可由可靠的分布式通知服务得到保证。     

Top-k/w publish/subscribe: A publish/subscribe model for continuous top-k processing over data streams

Continuous processing of top-k queries over data streams is a promising technique for alleviating the information overload problem as it distinguishes relevant from irrelevant data stream objects with respect to a given scoring function over time. Thus it enables filtering of irrelevant data objects and delivery of top-k objects relevant to user interests in real-time. We propose a solution for distributed continuous top-k processing based on the publish/subscribe communication paradigm—top-k publish/subscribe over sliding windows (top-k/w publish/subscribe). It identifies k best-ranked objects with respect to a given scoring function over a sliding window of size w, and extends the publish/subscribe communication paradigm by continuous top-k processing algorithms coming from the field of data stream processing.In this paper, we introduce, analyze and evaluate the essential building blocks of distributed top-k/w publish/subscribe systems: first, we present a formal top-k/w publish/subscribe model and compare it to the prevailing Boolean publish/subscribe model. Next, we outline the top-k/w processing tasks performed by publish/subscribe nodes and investigate the properties of supported scoring functions. Furthermore, we explore potential routing strategies for distributed top-k/w publish/subscribe systems. Finally, we experimentally evaluate model properties and provide a comparative study investigating traffic requirements of potential routing strategies.     

A scalable publish/subscribe system for large mobile ad hoc networks

Since nodes that compose mobile ad hoc networks (MANETs) does not have any prior knowledge about other nodes in many cases, the publish/subscribe communication paradigm that has the decoupling and asynchrony properties can be useful to share information between nodes. Existing publish/subscribe services for MANETs can be categorized into document flooding (DF), destination-based routing (DBR), and content-based routing (CBR). Although those approaches may work well when the size of network is small, all of them suffer from the performance decline as the size of the network increases. In this paper, we compare those approaches, and then propose a scalable publish/subscribe communication scheme in large MANETs by combining DF and CBR hierarchically. Our approach is to cluster all nodes in networks and to exploit CBR and DF for the intra- and inter-cluster communication, respectively. By using this approach, we can effectively utilize benefits of both approaches. Then, we present performance evaluation results which validate our idea with respect to system performance and scalability.     

发布订阅系统在移动Ad Hoc网络中的三种路由算法

介绍了分布式发布/订阅系统的原型，为Ad Hoc网络中的发布/订阅系统设计了三种基于内容的路由算法，分别说明了它们的运行方式，并进行了仿真与比较。结果表明：基于内容的可靠容错路由算法能够100%保证信息的传输，有容错机制，可靠性较强，但出现了传输延迟；基于内容的路由算法的可靠性不强，适合有线网络中分布式发布订阅系统的信息传输，传输延迟小；基于内容的容错路由算法有容错机制，传输延迟小     

基于ECA的信息发布/订阅机制研究

分布式的监控环境中,基于发布/订阅的push模式能及时地反映用户关注的最新信息,很好地满足松散通信的需要.但当订阅条件关联多条数据信息时,传统的订阅描述方法和匹配算法难以满足要求.提出了基于ECA(event-condition-action)的信息发布/订阅机制,利用ECA规则描述复杂的订阅条件,并初步研究了匹配方法.介绍了在卫星测试中该机制的设计实现及应用.     

B/S结构下的信息共享研究

当前的信息共享系统大多基于C/S结构,在部署升级、系统维护上存在着困难.本文首先介绍几种常用通信模型,然后在对已有Web信息共享实例分析的基础上,提出一个B/S结构下基于发布/订阅模型的信息共享解决方案.最后采用AJAX技术对方案进行了优化,并对方案中可能出现的问题进行相应的处理.     

高可用性负载均衡信息发布平台的设计

提出了一种基于集群系统设计思想的实时信息发布平台的系统结构和设计。该平台支持订阅／发布模式，能够同时接收大量用户的订阅，并提供了高可用性、可扩展的和负载均衡的信息发布服务。     

基于移动代理和密钥共享的发布/订阅系统的研究与设计

发布/订阅系统中信息的安全传输一直被忽视,一些保密的重要消息可能由于在传输过程中被人窃取而使得订阅者受到一定的损失.针对该问题,提出了一种基于移动代理的发布/订阅系统,该系统在传统的基于内容的发布/订阅系统中引入移动代理技术,从而有效地提高了系统的灵活性和可扩展性,使用可验证密钥共享算法能够进一步保证秘密信息的安全传输.最后,通过对各方面的性能分析,结果表明,该系统具备较高的安全性和灵活性.     

一种支持语义的发布／订阅系统

针对基于内容的发布／订阅系统中消息异构导致匹配准确率降低的问题,本文通过定义事件和订阅属性间的语义关系,利用语义转换模块,提出一种支持语义的发布／订阅系统的设计方法,并将其应用于SINEA发布订阅系统中。实验结果表明,该方法可在一定程度上支持语义异构,提高匹配的准确度。     

内容发布订阅系统的组播路由

基于内容的发布订阅系统多数采用泛洪和匹配优先的路由算法。本文提出了基于事件空间划分的发布订阅系统的实现方法,采用组播的方式实现了目标代理到多个订阅者之间的通知路由算法。与采用贪婪路由思想的单播路由算法相比较,该算法提高了在通知路由阶段的发布订阅系统的路由效率。算法对解决基于内容的发布订阅系统中相关的路由问题具有重要的作用和意义。最后给出了算法的仿真实验。     

Efficient and scalable filtering of graph-based metadata

RDF Site Summaries constitute an application of RDF on the Web that has considerably grown in popularity. However, the way RSS systems operate today limits their scalability. Current RSS feed arregators follow a pull-based architecture model, which is not going to scale with the increasing number of RSS feeds becoming available on the Web. In this paper, we introduce G-ToPSS, a scalable publish/subscribe system for selective information dissemination. G-ToPSS only sends newly updated information to the interested user and follows a push-based architecture model. G-ToPSS is particularly well suited for applications that deal with large-volume content distribution from diverse sources. G-ToPSS allows use of an ontology as a way to provide additional information about the data disseminated. We have implemented and experimentally evaluated G-ToPSS and we provide results demonstrating its scalability compared to alternative approaches. In addition, we describe an application of G-ToPSS and RSS to a Web-based content management system that provides an expressive, efficient, and convenient update notification dissemination system.     

轨道交通维保数据的P2P发布订阅系统

为实现轨道交通的运营安全保障,提高出现事故后的应急响应和维保效率,提出一种将各条轨道交通的地铁控制中心组织成结构化的P2P网络,构建面向轨道交通电力系统数据的分布式发布订阅系统平台,提高数据异地的使用效率和共享,为电力系统故障的快速维保提供信息支持.发布订阅系统的地铁控制中心推送电力系统数据到网络节点,当电力系统出现故障时,维保人员可以订阅方式从网络系统中及时得到故障报警、设备信息和现场环境参数,实现故障期间各部门抢修程序的并行执行.应用结果表明,该系统平台能有效提高轨道交通故障响应速率和维修效率.     

GoDisco++: A gossip algorithm for information dissemination in multi-dimensional community networks

In this paper we propose GoDisco++, a gossip based approach for information dissemination in online social community networks. GoDiscoo++ uses local information available to nodes—that is information associated with a node and its neighbors. The algorithm exploits multiple relations which may exist between nodes, and applies social principles and behavior inspired decentralized mechanisms for targeted dissemination. The dissemination process works with the dual aims of (i) maximizing the spread among relevant nodes (high recall) and (ii) minimizing spamming among non-relevant nodes (high precision). Such a designed dissemination scheme can have interesting applications like probabilistic publish/subscribe, decentralized recommendation and contextual advertisement systems, to name a few. We validate the proposed approach with simulation experiments performed using real and synthetic datasets.