文件传输协议在机顶盒中的研究

Study on File Transfer Protocol in Downloading

FTP下载这一大的功能模块可细分为节目管理、下载预约管理、节目下载3个小的模块。每个模块既相对独立,又相互相关。其中,节目管理模块负责节目的存放、查询等管理功能。下载、录制的节目根据节目名生成文件名存放在硬盘上。下载预约管理模块模块负责下载预约的预约记录、预约提取、逐个下载等功能。本模块通过调用节目管理模块的库函数,对节目进行预约,同时向FTP下载模块发送命令,接收消息,以便后续对下载进程进行控制。节目下载模块通过socket与主控进程通讯,接收主控进程发送过来发的控制命令,建立下载链接,进行下载,并随时将下载状态等信息反馈给主控进程,以便主控进程随时对下载进程进控制。3个模块相互合作,完成了FTP下载的整个过程。

FTP Download can be divided into Program Management module, Download Booking ,Management module and Program Download module. Program Management module is responsible for program s save and query. The download and recording program am saved in the hard disk according to the file name which created by program names. Download Booking Management module is responsible for recording and fetching booking , and downloading one bye one. This module calls the library functions in the Program Management module to program booking, and simultaneously sends command to or receives message from FTP downloading module , in order to control the dowrdoading process. Program Download module, via socket, communicates with control process, receives control command from control process, builds download linking, downloads program and feeds the download state back to control process at any time needed which means the control process control the download process all the time. The three modules cooperate with each other to finish the whole download process.