Design and implementation of a dynamic content cache module for Web server

Web offers a very convenient way to access remote information resources, an important measurement of evaluating Web services quality is how long it takes to search and get information. By caching the Web server‘s dynamic content, it can avoid repeated queries for database and reduce the access frequency of original resources, thus to improve the speed of server‘s response. This paper describes the concept. advantages, principles and concrete realization procedure of a dvnamic content cache module for Web server.     

基于Internet的高速缓存技术分析

Internet的迅速发展 ,使网上的数据量惊人地增加 ,造成网络带宽严重不足。高速缓存是一种对频繁访问 Web信息的请求在本地实现的技术 ,它能降低 Internet的信息流量、提高用户的访问速率。文章在研究了高速缓存工作原理的基础上 ,综合分析了基于 Internet的缓存技术的 3种实现方案 :基于浏览器的客户机缓存、代理服务器和网络缓存 ,分析了它们各自的工作特点和应用场合 ,并展望了缓存技术的应用前景。     

A New Framework for Focused Web Crawling

Focused crawlers are important tools to support applications such as specialized Web portals, online searching, and Web search engines. A topic driven crawler chooses the best URLs and relevant pages to pursue during Web crawling. It is difficult to deal with irrelevant pages. This paper presents a novel focused crawler framework. In our focused crawler, we propose a method to overcome some of the limitations of dealing with the irrelevant pages. We also introduce the implementation of our focused crawler and present some important metrics and an evaluation function for ranking pages relevance. The experimental result shows that our crawler can obtain more ＂important＂ pages and has a high precision and recall value.     

KDS-CM： A Cache Mechanism Based on Top-K Data Source for Deep Web Query

Caching is an important technique to enhance the efficiency of query processing. Unfortunately, traditional caching mechanisms are not efficient for deep Web because of storage space and dynamic maintenance limitations. In this paper, we present on providing a cache mechanism based on Top-K data source （KDS-CM） instead of result records for deep Web query. By integrating techniques from IR and Top-K, a data reorganization strategy is presented to model KDS-CM. Also some measures about cache management and optimization are proposed to improve the performances of cache effectively. Experimental results show the benefits of KDS-CM in execution cost and dynamic maintenance when compared with various alternate strategies.     

基于HTTP协议的动态页面缓冲技术的研究

在分析了ＨＴＴＰ协议的缓冲机制及ＷＷＷ服务器中动态页面的主要特点的基础上,提出了一个基于实体标签的动态页面缓冲算法,该算法对ＷＷＷ服务器在ＯＬＴＰ应用系统中的性能有较明显的改善作用·     

活动缓存模式在知识管理系统中的应用

动态文档正在成为Web内容中越来越重要的组成部分,获取动态内容的缓存成为影响Web规模的重要课题.笔者提倡用“活动缓存模式”来支持动态内容在Web代理上的缓存.这种模式允许服务器提供“缓存小应用”,这些小应用与内容绑定,需要代理根据缓存命令中判定的结果调用缓存小应用来完成必要的处理,而不需要与服务器联系.说明活动缓存模式涉及的协议、接口和安全机制,阐述了在当前的知识管理系统中如何引入活动缓存机制,以此来解决在应用规模不断扩大和数据量不断增加的情况下知识管理系统服务器服务性能问题.     

Design and Implementation of Hierarchy Cache Using Pagefile

This paper presents a novel hierarchy cache architecture for the purpose of optimizing IO performance. The main idea of the hierarchy cache is to use a few megabytes of RAM and a pagefile to form a two-level cache architecture. The pagefile is equivalent to the cache disk in DCD(Disk Caching Disk). The pagefile outperforms data disks, because data are accessed in different units and different ways. Small writes are collected in the RAM cache first, and data will be transferred to the pagefile in large writes later. When the system is idle, it will destage data from the pagefile to data disks. The performance test results show that the hierarchy cache can improve IO performance dramatically for small writes, and the mail server using the hierarchy cache driver can handle transactions about 2.2 times faster than the normal mail server. The hierarchy cache is implemented as a filter driver, so it‘s transparent to the current Windows 2000/Windows XP operating system.     

Testing Forms in Web Applications Automatically

Forms enhance both the dynamic and interactive abilities of Web applications and the system complexity. And it is especially important to test forms completely and thoroughly. Therefore, this paper discusses how to carry out the form testing by different methods in the related testing phases. Namely, at first, automatically abstracting forms in the Web pages by parsing the HTML documents; then, ohtai ning the testing data with a certain strategies, such as by requirement specifications, by mining users＇ hefore input informarion or by recording meehanism; and next executing the testing actions automatically due to the well formed test cases; finally, a case study is given to illustrate the convenient and effective of these methods.     

Improved caching policies and hybrid strategy for query result cache

To improve efficiency of search engines,the query result cache has drawn much attention recently.According to the query processing and user' s query logs locality,a new hybrid result cache strategy which associates with caching heat and worth is proposed to compute cache score in accordance with cost-aware strategies.Exactly,query repeated distance and query length factor are utilized to improve the static result policy,and the dynamic policy is adjusted by the caching worth.The hybrid result cache is implemented in term of the document content and document ids(doclds) sequence.Based on a score format and the new hybrid structure,an initial algorithm and a new routing algorithm are designed for result cache.Experiments' results show that the improved caching policies decrease the average response time effectively,and increase the system throughput significantly.By choosing comfortable combination of page cache and doclds cache,the new hybrid caching strategy almost reduces more than 20%of the average query time compared with the basic pageonly cache and docld-only cache.     

Cache Coherency Design in Pentium Ⅲ SMP System

This paper analyzes cache coherency mechanism from the view of system. It firstly discusses caehe-memory hierarchy of Pentium Ⅲ SMP system, including memory area distribution, cache attributes control and bus transaction. Secondly it analyzes hardware snoopy mechanism of P6 bus and MESI state transitions adopted by Pentium Ⅲ. Based on these, it focuses on how muhiprocessors and the P6 bus cooperate to ensure cache coherency of the whole system, and gives the key of cache coherency design.     

Web缓存系统浅析

研究和构造一个可扩展性好及请求命中率高的Web缓存系统，通过对Web缓存定位问题及目前流行的分布缓存系统的分析，确定分层缓存系统更有优势，为了提高分层缓存的可扩展性和请求命中率，在保持父子代理之间原有协作关系的同时加强父代理的处理能力，提出了一种新的虚拟协作缓存系统，即父代理用扩展性好的集群系统实现，子代理在缓存的同时加进预取技术，该虚拟制作缓存系统能满足网络缓存对可扩展性及请求命中率的要求，具有可扩展性好，吞吐率高和命中率高的特点。     

一种基于分段的网络流媒体代理缓存策略

针对大量用户访问网络流媒体系统时出现的响应速度慢、网络拥塞严重、缓存利用率低和容量不足的问题,提出了一种IPTV环境下的PSU代理缓存策略,利用分段缓存和动态调整存储比例的方法,提高流媒体代理服务器的存储效率和服务性能.给出了流媒体文件的分段方法和热度概念,通过增加前缀缓存数量的方法,优化了IPTV三层结构的存储比例,...     

ASP环境下交互网页的设计

随着互联网的发展，Web信息服务越来越广泛，目前，Web技术大量使用交互式网页技术。主要介绍了如何在ASP环境下通过ASP的内建对象去实现动态网页，以及ActiveX组件及ADO组件技术在ASP中的应用。     

A new algorithm for routing in ad-hoc network

In this paper, we propose a new algorithm for wireless mobile and ad-hoc network, which establishes dynamic cluster of nodes. The proposed algorithm, namely, the Mobility Sensitive Routing Protocol (MSRP), consists of routing in cluster and routing between clusters. Ad-hoc network can utilize MSRP to reduce information exchange and communication bandwidth, to shorten route acquisition delay, and to accommodate more nodes. Foundation item: Supported by the National Natural Science Foundation of China (60133010,60073043,70071042). Biography: Zhang Jian (1976-), male, Ph. D candidate. Lecturer, research direction: computer network, network optimization.     

Web日志预处理中会话识别的优化

针对目前的各种会话识别方法,提出了一种优化的会话切分方法.该方法基于对用户下载时间、对页面的平均阅读时间及页面的链入、链出数等几个参数的综合,得到每个用户页面的访问时间阈值,根据该阈值来切分用户会话,得到会话侯选集合;然后,根据用户对页面内容的兴趣度、浏览特性等来删除会话中的链接页面和不感兴趣的页面,生成一种最终有效的访问页面序列,从而为以后的模式发现提供良好的数据.实验结果表明,相对于所有用户使用单一先验阈值和使用统计方法结合页面内容确定阈值的方法,笔者提出的方法能更准确地确定页面访问时间阈值,得到更为合理有效的会话集合.     

基于ISAPI过滤器的网页防篡改系统

首先分析了几种常用网页防篡改技术的特点,然后提出并实现了一种基于ISAPI过滤器的网页防篡改系统.该网页防篡改系统可以高效地监控网页内容的变化,对于被篡改的网页文件能在其被用户访问之前自动加以恢复,使用该系统能方便网站的管理,并能帮助网站管理员及时地了解网站信息.     

基于Internet的代理缓存技术的研究

讨论基于Internet的代理缓存的目标、性质和工作原理,从而论述了代理缓存技术成为解决Web访问速度慢、服务器负载重和网络阻塞等问题的主流技术的原因.最后,指出基于Internet的代理缓存技术仍存在的一些问题和研究前沿.     

Similarity Measurement of Web Sessions Based on Sequence Alignment

The task of clustering Web sessions is to group Web sessions based on similarity and consists of maximizing the intra-group similarity while minimizing the inter-group similarity. The first and foremost question needed to be considered in clustering Web sessions is how to measure the similarity between Web sessions. However, there are many shortcomings in traditional measurements. This paper introduces a new method for measuring similarities between Web pages that takes into account not only the URL but also the viewing time of the visited Web page. Then we give a new method to measure the similarity of Web sessions using sequence alignment and the similarity of Web page access in detail Experiments have proved that our method is valid and efficient.