基于Webkit的网站加载过程监控系统的设计

本论文通过分析开源浏览器引擎Webkit的基本框架及HTTP请求的处理流程,设计了基于Webkit浏览器内核的网站加载过程的监控系统。该监控系统模拟浏览器加载网站的过程,记录网站中所有资源加载过程的监控信息。     

虚拟主机云存储系统VCloudStorage及文件传输协议VCFTP

对于广域网下的文件传输和管理,云存储系统提供Web Service API、基于文件的API、基于Block的API和其他的API,通常需要在客户端安装特定程序调用这些API实现云存储功能,测试发现如果多人同时访问,传输文件失败率较高。设计了基于Web Service、HTTP和Flash技术的文件传输协议VCFTP,开发了基于虚拟主机集群的云存储系统VCloudStorage。首先建立SaaS服务模型,利用HTTP数据流存储技术,建立虚拟主机存储接口;接着建立虚拟主机传输能力、存储能力和价格能力数学模型,结合用户的传输请求建立文件传输整数规划数学模型及最优化算法,最终以此为基础设计了文件传输控制协议VCFTP。VCFTP利用Flash跨平台和富客户端技术特点,无需在客户端部署其他程序;授权的用户根据传输请求、存储要求、服务水平和当前虚拟主机状态等条件,以传输能力最优化的方式进行文件传输。实验结果表明VCFTP具有较高的性能和稳定性,VCloudStorage总吞吐量、平均传输率和文件传输成功率均优于微软SkyDrive存储、腾讯QQ邮箱存储和单虚拟主机存储。本文提出的VCFTP增强了文件传输性能和稳定性,是提高广域网网络存储系统性能的一条有效途径。     

一种高性能异步RPC框架的设计与实现

为了研究RPC技术的原理以及提高性能和可用性的方案,设计并实现了一种名为Pretty RPC的RPC框架。Pretty共分三层:公共层,核心层和应用层。整体设计围绕高性能、高可扩展性,高可用性及高易用性等特点进行。采用Netty高性能异步通信框架用于信息交互;Protostuff框架提供对象序列化能力;JDK Proxy技术生成代理对象;Spring框架提供基于Io C的对象管理功能。最终实现了一种符合预期的RPC框架。经过此次研究实践,能够得出如下结论:基于改进Reactor模式的纯异步线程池通信模型的效率要高于传统多线程同步阻塞的通信模型;序列化算法的效率也是决定RPC性能的重要因素之一;基于Io C思想的软件设计方式能够有效提升软件的各项指标。     

AJAX技术在学生收费系统中的应用研究

AJAX是异步的JavaScript和XML.在AJAX之前,Web开发中采用的是同步交互方式,如JSP,但其后果是客户端必须一直等待服务器的响应,以至于冻结页面,有时用户不得不离开访问页面.在此研究了基于AJAX异步刷新而提供与服务器异步通信的能力,从而使用户从请求/响应的循环中解脱出来,以实现异步动态更新.     

浅析电信营运商信息化建设之负载均衡技术优化加速HTTP应用

负载均衡技术通过设置虚拟服务器IP（VIP）,将后端多台真实服务器的应用资源虚拟成一台高性能的应用服务器,使用负载均衡算法,将大量来自客户端的应用请求分配到后端的服务器进行处理。通过负载均衡设备提供的HTTP优化和加速功能,能够大大提升电信运营商后端服务器系统的处理能力,降低服务器端负载情况,节约服务器资源和广域网链路带宽,从而大大减少电信运营商的用户在请求访问服务时所等待响应的时间。     

基于J2EE的高校后勤管理系统的研究和实现

运用SSI开源框架集成了Struts框架、Spring框架和IBatis框架,提出基于J2EE的高校后勤管理系统。该系统将开源框架与Ajax技术相结合,可实现系统的异步提交,减轻网络通信和服务器端的负担;以后勤管理数据为研究对象,通过数据仓库、OLAP、数据挖掘技术的综合运用发现后勤管理系统中的有用信息,为管理高层提供辅助决策支持,具有较强的实用价值。     

OpenStack Swift服务访问层的设计及实现

OpenStack Swift服务是一个开源的云存储项目,用其提供的存储对象访问层应用程序接口,接合OpenStack的Keystone安全访问机制及RESTful软件架构风格,设计了灵活、安全稳定的面向对象的分布式存储对象管理方案,并实现了Android移动客户端以HTTP1.1协议对分布式存储对象的上传、下载、删除、查询、更新等管理操作,以此验证设计方案的可行性.     

基于页面差异模式的Ajax框架设计及实现

在研究了现有Ajax框架的基础上,提出了基于页面差异模式实现Ajax框架的模型,并在.NET平台中实现了该模型。该模型改进了请求数据传输方法,分别在浏览器和服务器两端实现了请求响应数据的差异处理。经实验对比,基于页面差异模式的Ajax框架可以进一步缩减HTTP请求和响应数据包的大小,明显提高Web应用程序响应效率。     

Osip协议栈移植到μc/os系统的方法及其应用

文中对SIP协议的基本原理、组成和功能进行了介绍。对SIP协议的开源协议栈Osip和eXosip做了进一步分析,并将Osip和eXosip协议栈移植到μc/os操作系统中作为SIP客户端,实现了μc/os系统下SIP客户端中多用户向SIP服务器注册、响应SIP服务器对客户端任意用户的呼叫请求的功能。     

基于Solr的企业级搜索引擎的设计

分散的计算机上存储有大量的信息,企业级用户急需一种工具对这些零散的信息进行统一的查找,最好还可通过配置对特定的网站进行检索,这就是企业级搜索引擎,本文使用开源项目Solr设计了一款面向企业的搜索引擎。整体设计基于SSH设计框架实现;服务器端采用Heritrix抓取网页,加入IKAnalyzer增加中文分词功能;客户端采用Ajax技术实现异步通信,优化用户体验。     

基于Key-Value的内存缓存系统在OMP鉴权中心中的应用

OMP(Open Mobile Platform,能力开放平台)是中国移动集团为开放其基础能力给开发者进行应用开发以满足用户个性化需求,并提供相应的运营管理功能的通用平台。为了降低鉴权中心数据库负载、提高应用的处理和响应速度,引入了一种高性能的内存缓存系统Redis。本文简单介绍了Redis系统并将其应用于OMP鉴权中心,最后对存在的问题进行分析并提出改进建议。     

Segment‐aware dynamic routing for DASH flows over software‐defined networks

Most of the video streaming applications running over the Internet send video data over HTTP and provide an architecture for video clients to adapt video quality during streaming. In HTTP adaptive streaming, a raw video is encoded at various qualities, each encoded video file is divided into small segments, and the clients may change the segment quality by sending requests for segments having different qualities over time. MPEG has standardized dynamic adaptive streaming over HTTP (MPEG‐DASH) due to this tendency. In this work, we focus on DASH over software‐defined networks (SDN), and we dynamically reroute DASH flows by considering the current network capacity, available bandwidth of the paths, and bitrate of the segments in order to provide high quality of experience (QoE) and fairness among DASH clients. Simulations performed under various network conditions show that the proposed study provides higher QoE and fairness compared with the max‐flow routing approach.     

Managing routing tables for URL routers in content distribution networks

Large‐scale content distribution networks (CDNs) can be built using URL routers to redirect client HTTP requests to the nearest content source. URL routers employ very large routing tables. To improve the manageability of CDNs, we propose to use URL signatures to reduce the size of routing tables and aggressive hashing to speed‐up routing look‐ups. Copyright © 2004 John Wiley & Sons, Ltd.     

NTP-SIOT: A test tool for advanced mobile services

This article describes system design for an Open Mobile Alliance Service Interoperability Test Platform called NTP-SIOT. Based on the TTCN-3 specifications, we show how 4G mobile applications such as OMA multimedia messaging service can be tested in this platform     

Research on HTML5 application cache poison attack

HTML5 application cache (AppCache) allowed Web browser to access Web offline.But it also brought a new method of cache poisoning attack that was more persisting.As for websites which used the AppCache,a novel poisoning method RFTM (replace file twice method),in which the attacker replaced the manifest file twice to poison the client’s AppCache,was proposed.Compared with the original attack,the legal server would not receive abnormal HTTP requests from the client in the attack.Therefore,changing the server configuration could not prevent the client from the RFTM AppCache poisoning.To avoid the attack mentioned above,a lightweight signature defense scheme Sec-Cache in application layer was designed.Furthermore,experiments show that it has good performance and compatibility.     

基于DFA的HTTP会话学习模型

由于Web应用涉及范围广,结构复杂多变等特点,对其采用的入侵检测面临着严峻的考验。具有学习功能的入侵检测有着广阔的研究前景。提出一种异常检测方法,从HTTP连接中提取HTTP会话,按照RFC标准描述HTTP请求,以此构建基于DFA的HTTP会话学习模型。并针对HTTP请求数量庞大的特点,提出模型简化的算法。该模型能够实现自动更新,有助于解决入侵检测保护Web应用时遇到的问题。     

A game theoretic approach to power aware wireless data access

We consider a basic scenario in wireless data access: a number of mobile clients are interested in a set of data items kept at a common server. Each client independently sends requests to inform the server of its desired data items and the server replies with a broadcast channel. We are interested in studying the energy consumption characteristics in such a scenario. First, we define a utility function for quantifying performance. Based on the utility function, we formulate the wireless data access scenario as a noncooperative game - wireless data access (WDA) game. Although our proposed probabilistic data access scheme does not rely on client caching, game theoretical analysis shows that clients do not always need to send requests to the server. Simulation results also indicate that our proposed scheme, compared with a simple always-request one, increases the utility and lifetime of every client while reducing the number of requests sent, with a cost of slightly larger average query delay. We also compare the performance of our proposed scheme with two popular schemes that employ client caching. Our results show that caching-only benefits clients with high query rates at the expense of both shorter lifetime and smaller utility in other clients.     

利用netfilter NFQUEUE实现网关认证的HTTP重定向

利用netfilter的NFQUEUE机制,将未认证用户的TCP 80端口流量发送至用户态进程redir_http,redir_http使用原始套接字发送应答数据分组,在用户态实现HTTP重定向功能。这种实现方法既保证了重定向的高性能,又能避免Linux内核中的繁琐程序开发,降低程序开发复杂度,提高系统运行的稳定性。     

A RESTful image gateway for multiple medical image repositories

Mobile technologies are increasingly important components in telemedicine systems and are becoming powerful decision support tools. Universal access to data may already be achieved by resorting to the latest generation of tablet devices and smartphones. However, the protocols employed for communicating with image repositories are not suited to exchange data with mobile devices. In this paper, we present an extensible approach to solving the problem of querying and delivering data in a format that is suitable for the bandwidth and graphic capacities of mobile devices. We describe a three-tiered component-based gateway that acts as an intermediary between medical applications and a number of Picture Archiving and Communication Systems (PACS). The interface with the gateway is accomplished using Hypertext Transfer Protocol (HTTP) requests following a Representational State Transfer (REST) methodology, which relieves developers from dealing with complex medical imaging protocols and allows the processing of data on the server side.     

基于DSS的定制客户端测试工具的实现

详细介绍了DSS(Darwin Streaming Server)中的RTSP协议交互过程,用VC6.0实现定制客户端测试工具,模拟并发用户实现对DSS的多文件点播并发支持能力的测试,对定制客户端进行扩展,可以实现对修改后的DSS(支持MPEG-2 TS格式)并发访问,通过查看DSS的WEB管理端以及用Wireshark抓包工具进行抓包对定制客户端进行验证,结果证明,设计的定制客户端可以模拟并发用户与流媒体服务器进行RTSP交互,在对流媒体软件点播并发能力的测试中有很好的应用。