节点文献
基于PowerPC的嵌入式网络下载器（FTP和HTTP部分）
An Embedded Network Downloader Based on PowerPC (FTP and HTTP Section)
【作者】 马辉；
【导师】 朱绣鑫；
【作者基本信息】 天津大学 ， 通信与信息系统， 2007， 硕士
【摘要】 随着现代数字信息技术和网络技术的高速发展,如何更有效、更方便地下载、存储、管理、共享、交换数据资源,成为人们关注的一个问题。现有的网络存储器虽然性能卓越,但存在体积庞大、价格高昂和操作不便等问题,无法真正解决个人、家庭和小型企业用户的问题。同时,在现代信息社会,各种类型的数据也呈几何指数级增长,用计算机从网络上下载它们往往需要很长时间,不仅浪费时间、浪费能源和具有安全隐患,还有很大的不便利性。本课题设计开发的嵌入式网络下载器,为中小用户提供了一种解决方案。它采用嵌入式设计,结构简单,成本低,功耗小,适合长期开机使用,不仅可以作为网络存储器,还能自动从网络上下载指定的资源,并且支持多种下载协议。本文主要介绍了本人在该课题中承担的工作。首先,根据嵌入式系统的原理和开发过程,通过比较常用的嵌入式处理器和嵌入式操作系统的特点,结合嵌入式网络下载器的功能需求,设计出系统的总体方案。然后,通过分析FTP和HTTP协议,设计实现了这两种协议的下载程序,文中详细介绍了其实现过程和方法,给出了主要流程图和关键代码。最后简单介绍了程序的移植和验证过程。本设计实现的下载程序适合在嵌入式平台上运行,具有较强的任务管理功能,实现了多任务多线程下载功能,能显著提升下载速度和缩短下载时间,并且解决了断点续传问题。
【Abstract】 With the rapid development of nowadays digital information and network technology, the efficiency and convenience of data resource’s downloading, storage, management, sharing and exchanging are gradually coming into people’s sight. Despite the good performance of existing NAS, large size, high price and poor user interface are still the main barriers for personal or home users, and even for some small enterprises.Meanwhile, in nowadays information society, various types of data are increasing at a geometric progression, therefore, downloading them from Internet with a desktop is often time-consuming and often involves resource waste and safety problem.This project aims to design an embedded network downloader suitable for personal users. It is embedded application oriented and simple-structured with low cost and power, supporting long-time online work. As a network downloader for specified resource acquisition as well as an NAS, it can automatically start downloading and is compatible with many transfer protocols.The paper is mainly about what I do in this project. According to the nominal development procedure and method of embedded system, different common embedded processors and embedded operation systems are compared for the requirements of our downloader product, and the general design scheme is introduced. Then, an FTP and an HTTP client are designed by the analysis of FTP and HTTP. The implementation procedure and method is expounded. Flow chart and key function’s code are presented. Finally, the porting and testing issues are introduced.The FTP and HTTP clients implemented in this project are suitable for embedded system. They have powerful task management function, and multiple tasks multiple threads download function, which can increase download speed and shorten download time obviously. The implementation of download resuming is also introduced in the paper.