基于HDFS的分布式长期保存系统实现研究

随着信息社会发展,海量数字信息资源存储的需求变得越来越普遍,使用分布式文件存储是一种有效的解决方案。文章通过分析HDFS本身信息存储交互的特点,给出了使用HDFS的长期保存分布式存储实现方案,为今后使用HDFS及Fedora进行分布式长期保存及管理提供了借鉴参考。     

分布式数据库在银行代理业务中的实现模型

就银行代理业务在分布式数据库上的实现进行了研究，借助于J2EE规范中的EJB技术来实现对分布式数据库的操作．并利用数据访问对象模式来封装数据存储的细节，实现EJB组件与数据库的松散耦合；用值对象模式封装相关的业务数据，减少数据库的频繁操作，以提高系统性能．     

p2pDating: Real life inspired semantic overlay networks for Web search

We consider a network of autonomous peers forming a logically global but physically distributed search engine, where every peer has its own local collection generated by independently crawling the Web. A challenging task in such systems is to efficiently route user queries to peers that can deliver high quality results and be able to rank these returned results, thus satisfying the users’ information need. However, the problem inherent with this scenario is selecting a few promising peers out of an a priori unlimited number of peers. In recent research a rather strict notion of semantic overlay networks has been established. In most approaches, peers are connected to other peers based on a rigid semantic profile by clustering them based on their contents. In contrast, our strategy follows the spirit of peer autonomy and creates semantic overlay networks based on the notion of “peer-to-peer dating”. Peers are free to decide which connections they create and which they want to avoid based on various usefulness estimators. The proposed techniques can be easily integrated into existing systems as they require only small additional bandwidth consumption as most messages can be piggybacked onto established communication. We show how we can greatly benefit from these additional semantic relations during query routing in search engines, such as Minerva, and in the JXP algorithm, which computes the PageRank authority measure in a completely decentralized manner.     

Observer模式在.Net分布式开发中的应用

在面向对象的软件设计中恰当地应用设计模式,将简化开发过程,使系统结构清晰,便于扩展和维护。对观察者设计模式(Observer)进行了分析,并利用.Net框架的特性对其进行了改进,最后利用改进后的模式基于.NetRemoting技术进行了分布式开发的实践。     

基于企业Intranet的信息集成框架设计

如何实现CIMS的信息集成是企业Intranet架构的关键所在,传统的C/S体系结构由于其维护性差、安全性不高等缺点已经不能适应企业发展的需求,采用一种基于浏览器及分布式对象计算技术的多层框架结构来实现信息集成,具有较好的可扩展性、安全性和可靠性,并能很好地适应企业分布式异构环境。     

浅述楼宇自动化系统及其总线控制

阐述了楼宇自动化控制系统的发展历程和各自的优缺点,分析了总线控制技术,并探讨了现阶段楼宇自控系统中现场总线控制与集散控制相结合与应用。     

浅谈P2P系统中的资源定位

P2P(peer-to-peer)模式是互联网的重要应用之一,资源定位是实现P2P网络资源共享的前提条件。本文首先介绍国内外P2P资源定位的研究现状,接着介绍了P2P网络的四种模型,然后介绍目前P2P资源定位的一些方法以及对这些方法的优化,如泛洪、随机漫步、基于分布式哈希表的查找等。     

基于分布式查询的数据转储应用

在校园内部业务与外部业务的网络互不连接的工作环境下,如何使内部业务的数据转储到外部系统中,发布在互联网上,文章提出了基于分布式查询的转储策略,并进行了数据库级实现.     

New structures of power and regulation within ‘distributed’ education policy – the example of the US Common Core State Standards Initiative

Abstract

This article focuses on the growing development towards new forms of ‘distributed’ governance within current large-scale educational reforms. The emphasis is on so-called ‘governance through standards’ as a transformative reform complex which manifests itself in a simultaneous process of regulative destabilisation and (global) reconstruction of policy control. This newly emerging regulative policy ‘ensemble’ is found to be directly related to the growing collaborative activity of cross-field networks between governmental, non-governmental and private actors. Empirically, this article refers to the so-called Common Core State Standards (CCSS) Initiative which has fundamentally reshaped US education policy since 2001. The initiative comprised the negotiation, implementation and controlling of supra-state core skill standards for K-12 education as the benchmark for other regulating instruments such as assessments, monitoring and teacher training. In the context of the CCSS, the aforementioned new structures of regulation can then be located within an entrepreneurial alliance around the non-profit organisation Achieve, Inc. Through its function as a core policy network manager, Achieve generated simultaneous practices of collaboration and distinction, discourse initiation and (invisible) norm stabilisation.     

Engineering a multi-purpose test collection for Web retrieval experiments

Past research into text retrieval methods for the Web has been restricted by the lack of a test collection capable of supporting experiments which are both realistic and reproducible. The 1.69 million document WT10g collection is proposed as a multi-purpose testbed for experiments with these attributes, in distributed IR, hyperlink algorithms and conventional ad hoc retrieval.WT10g was constructed by selecting from a superset of documents in such a way that desirable corpus properties were preserved or optimised. These properties include: a high degree of inter-server connectivity, integrity of server holdings, inclusion of documents related to a very wide spread of likely queries, and a realistic distribution of server holding sizes. We confirm that WT10g contains exploitable link information using a site (homepage) finding experiment. Our results show that, on this task, Okapi BM25 works better on propagated link anchor text than on full text.WT10g was used in TREC-9 and TREC-2000 and both topic relevance and homepage finding queries and judgments are available.