共查询到18条相似文献,搜索用时 343 毫秒
1.
2.
3.
4.
5.
6.
构建大规模分布式基于内容的发布订阅系统仍然面临挑战。大多数现存的系统使用简单、事先定义的、静态的覆盖网络拓扑结构,这导致其具有较差的伸缩性和容错性。提出了一个构建于P2P网络之上的基于内容的发布/订阅系统,借助Pastry网络实现了基于内容的路由协议,其路由算法通过集中点机制避免了全局网络广播并且具有自组织和容错的特性,能够处理任意节点或者链路的失效。仿真结果表明该系统具有较好的路由效率和伸缩性,事件代理所需维护的路由表也更小。 相似文献
7.
8.
9.
基于聚类的图像分割算法是其中常见的一种,传统聚类算法需人为确定初始聚类中心和类别数,针对如何确定最优聚类类别数的问题,基于邻接矩阵提出一种自适应图像分割算法,该算法克服了传统聚类算法人为确定初始聚类中心和聚类类别数而导致局部最优的缺陷。利用实验数据将算法和传统聚类算法比较,并应用于图像分割。实验结果显示,算法稳定性较好,能自适应的得到准确地聚类类别数,且鲁棒性较强,在应用于图像分割时的聚类结果相对与传统聚类算法更加准确。 相似文献
10.
在介绍了消息中心整体架构的基础上,详细探讨了与TcgChannel技术相结合的消息发布/订阅模式平台的实现.该平台符合实际的监控业务需求,很好地支持了各部门消息订阅、分布式监控以及多种监控通知方式等功能.各模块之间耦合度小,具有良好的可扩展性.适用于传统分布式的监控系统,并在实际应用中已得到验证. 相似文献
11.
12.
在RFID信息服务网络中,设计了一种支持复合订阅的可靠的路由算法:在订阅转发阶段,我们将每一个复合订阅按照其语法结构进行分解,并将每个复合订阅成份分配给多个RFID信息服务(构成一个复合订阅存储单元)去维护,而事件则按照订阅分解的反方向和匹配的结果进行转发与合并.由于每个复合订阅存在多个副本,因而会显著减少因某个副本失效而产生的事件丢失.本文也给出了复合订阅存储单元内部多个复合订阅副本一致性的保持方法,以及核心信息服务的选举方法.实验结果表明,该路由算法有较高的容错性,性能可以满足实际应用的需要. 相似文献
13.
A publish/subscribe system dynamically routes and delivers events from sources to interested users, and is an extremely useful communication service when it is not clear in advance who needs what information. In this paper we discuss how a publish/subscribe system can be extended to operate in a mobile environment, where events can be generated by moving sensors or users, and subscribers can request delivery at handheld and/or mobile devices. We describe how the publish/subscribe system itself can be distributed across multiple (possibly mobile) computers to distribute load, and how the system can be replicated to cope with failures, message loss, and disconnections. 相似文献
15.
基于消息的企业应用程序之间的交互越加受到关注,它主要使用发布,订阅机制实现数据(消息)的交换。但是大多数的发布,订阅通知服务均假定在同一命名空间,不支持异构空间的应用之间的数据交换。首先简要描述了用于消息的分布式异构应用程序之间的作为高层发布机制基于概念的方法,然后讨论了设计和应用该发布机制的相关问题,以及如何将该机制集成于J2EE平台的方法。 相似文献
16.
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. 相似文献
17.
由于数据分发服务(DDS)一方面定义了以数据为中心的发布/订阅模型,允许应用程序实时地发布信息,并订阅所需要的信息;另一方面还提供了异步、松耦合、实时可靠数据分发服务质量(QoS)服务。所以,DDS 适用于性能要求高、可预见性强的军用实时关键任务领域。文中针对全国产化 DDS 产品ZRDDS,从处理器、操作系统、通信方式的差异性屏蔽 方法给出了跨平台实现策略,并以国产化华睿 2 号处理平台为例,对关键路径进行瓶颈分析,找出优化点,同时针对硬件 平台的特性给出优化方法。文中所述技术具有普适性,适用于各类通信中间件的设计,优化后的通信中间件 ZRDDS 可广泛应用于各类军用即时分布式系统。 相似文献
18.
Online social media exhibit massive organizational event relevant messages, and the well categorized event information can be useful in many real-world applications. In this paper, we propose a research framework to extract high quality event information from massive online media data. The main contributions lie in two aspects: First, we present an event-extraction and event-categorization system for online media data; second, we present a novel approach for both discovering important event categories and classifying extracted events based on word representation and clustering model. Experimental results with real dataset show that the proposed framework is effective to extract high quality event information. 相似文献