发布/订阅系统中基于属性集划分的并行搜索树

提出了依照并行搜索树的思想,将订阅的属性集划分为2个属性子集,在2个子集上分别构建一个并行搜索树。匹配事件时,在两个搜索树上分别得到该事件匹配的订阅集,两个集合的交集即为最终结果。分析及实验结果表明：划分并行搜索树可以减少搜索树的节点数,降低对存储空间的需求,并潜在地缩短事件匹配时间,尤其适合于节点分支数多而匹配分支少时的情况。     

CAER:一种基于内容的自适应事件路由算法

基于内容的发布/订阅模式正受到日益广泛的重视,为构建大规模分布式系统提供了一个很好的选择。在基于内容的事件分发中,事件发布结点无需指定分发的目标地址,事件在转发的过程中根据其内容逐步路由到对事件感兴趣的目标结点。针对已有的基于内容的路由算法不能适应订阅动态变化、网络通讯开销较大的问题,提出了一种基于内容的自适应事件路由算法CAER。通过在基于内容的路由表中将订阅与订阅源结点相绑定的方式,来实现路由表的构建和维护,使得路由算法适应订阅的动态变化。实验结果表明,该算法不仅提高了事件分发的准确率,而且降低了网络的通讯开销。     

Thoth – A publish/subscribe architecture for peer-to-peer tool integration

In experimental, iterative, and incremental development, the ad hoc use, and consequently integration, of heterogeneous tools supporting actual activities is crucial. This article looks at how peer-to-peer technologies may support such integration scenarios and introduces an architecture, Thoth, for peer-to-peer tool integration built on a publish/subscribe communication abstraction. Seen from an execution viewpoint, the Thoth architecture provides a simple platform for integration in which responsibility for integration is located at peers. Seen from a logical perspective, the Thoth architecture provides a set of object-oriented abstractions for an integration protocol. We present Thoth by means of two case studies of integration.     

面向事件的Agent感知模型研究

感知环境是Agent的基本属性，不同的环境要求Agent采用不同的感知方法。文章针对发布／订阅消息环境，以事件为感知对象，提出了一种网状事件合成机制，构建了一个适于Agent异步协作的感知体模型，给出了模型的定义、实现机制及应用评价。     

发布/订阅系统中的原子订阅管理和匹配

如何有效地管理原子订阅并将事件与原子订阅高效地匹配,是发布/订阅系统需要关注的关键问题.首先将原子订阅组织成为一个覆盖森林,然后在这个结构上执行原子订阅的匹配,同时使用谓词的多级索引结构为原子订阅匹配提供支持.此方法已在基于内容的发布/订阅系统OncePubSub上实现.给出了用于验证算法性能和开销的实验.实验结果表明,上述方法具有良好的匹配性能和可伸缩性.     

一种基于内容的数据分发网络及算法

物联网中通常需要对海量传感数据进行有目的的聚合和分发。设计中通常使用集中式的大规模存储系统管理海量物联数据,合适的数据分发机制对这样的存储系统必不可少。提出一种基于内容的数据分发网络设计。该设计可以和大规模存储中节点网络相结合,在保证存储过程不受影响的前提下收集空闲计算资源,高效完成基于内容的数据分发工作。受虚拟化思想的启发,设计引入“工作者”和“功能块”角色,通过动态调节每个节点上“工作者”的数量实现网络中节点的负载自动调节,同时通过动态装载或切换“功能块”实现不同任务之间计算资源的动态调配。还具体给出了一种基于布隆过滤器的分布式基于内容的数据分发算法。该算法分布于上述数据分发网络,同时通过使用布隆过滤器表示对象及其属性所满足的约束集合,消除了大量冗余计算,可以并行、高效地完成数据分发工作。     

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.     

DARGOS: A highly adaptable and scalable monitoring architecture for multi-tenant Clouds

One of the most important features in Cloud environments is to know the status and the availability of the physical resources and services present in the current infrastructure. A full knowledge and control of the current status of those resources enables Cloud administrators to design better Cloud provisioning strategies and to avoid SLA violations. However, it is not easy to manage such information in a reliable and scalable way, especially when we consider Cloud environments used and shared by several tenants and when we need to harmonize their different monitoring needs at different Cloud software stack layers. To cope with these issues, we propose Distributed Architecture for Resource manaGement and mOnitoring in cloudS (DARGOS), a completely distributed and highly efficient Cloud monitoring architecture to disseminate resource monitoring information. DARGOS ensures an accurate measurement of physical and virtual resources in the Cloud keeping at the same time a low overhead. In addition, DARGOS is flexible and adaptable and allows defining and monitoring new metrics easily. The proposed monitoring architecture and related tools have been integrated into a real Cloud deployment based on the OpenStack platform: they are openly available for the research community and include a Web-based customizable Cloud monitoring console. We report experimental results to assess our architecture and quantitatively compare it with a selection of other Cloud monitoring systems similar to ours showing that DARGOS introduces a very limited and scalable monitoring overhead.     

基于发布／订阅通信的动态数据集成模型

提供灵活、动态、一致和开放的数据集成模型对于通过集成异构信息资源,实现大规模企业信息系统至巷尊要。本文以中介模型为基础,提出了一种基于发布／订阅通信的动态数据集成模型,与相关工作相比,该模型的显著特点在于通过发布／订阅机制支持信息资源的动态可插拔、支持分布的信息检索、提供了动态可配置框架、集成节点具有对等性。     

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.     

Mires: a publish/subscribe middleware for sensor networks

A wireless sensor network (WSN) consists of a large number of small devices with computational power, wireless communication and sensing capability. These networks have been developed for a wide range of applications, such as habitat monitoring, object tracking, precision agriculture, building monitoring and military systems. Meanwhile, middleware systems have also been proposed in to facilitate both the development of these applications and provide common application services. The development of middleware for sensor networks, however, places new challenges on middleware developers due to the low availability of resources and processing capacity of the sensor nodes. In this context, this paper presents the design and implementation of a middleware for WSN named Mires. Mires incorporates characteristics of message-oriented middleware by allowing applications communicate in a publish/subscribe way. In order to illustrate the proposed middleware, we have also developed an environment-monitoring application and a data aggregation service.

基于信息空间划分的高效发布订阅路由技术

在大规模的基于内容发布订阅系统中,路由效率是影响系统性能的关键因素.本文在基于K-D树划分信息空间方法实现内容发布订阅系统的基础上,利用K-D树的索引机制,实现了面向扁平网络的应用层分级路由算法Spanhop.该算法机制减少了应用层路由跳,将路由效率提高到O(lnN).进一步,针对路由算法中应用层和网络层相邻关系不一致的问题,采用GNP(Global Network Position)空间与ESPN(Evem Space Partition Network)空间建立映射关系并在代理网络中维护GNP坐标索引的方法,支持应用层代理基于网络层的相邻关系搜索并选择下一跳路由.该方法减少了Spanhop路由过程中消息在网络层的实际转发路径和响应时间,在低维护代价条件下,提高了路由的效率.算法性能分析表明,上述方法解决了基于信息空间划分的内容发布/订阅系统的路由效率问题.     

基于混合通信模式的消息中间件设计与实现

将发布／订阅和点对点两种消息通信模式相结合,提出并设计了一种基于混合通信模式的消息中间件系统,并针对系统实现中的关键问题提出了相应的解决策略。测试结果表明,该系统综合了两种通信模式的优点,在保证灵活性和可靠性的同时,消息传输效率也得到了有效提高。