Chapter 5: Developing an FTP Client Application

File transfer is an important networking task, and File Transfer Protocol (FTP) client applications are still in wide use despite the ever-increasing popularity of the Web. The FTP client application built for this chapter complies with the current standard as specified in RFC959 by the World Wide Web Consortium (http://www.w3.org); you can use it to connect to and engage in file transfer with standard FTP servers. The main purpose of developing this application is to show how to work with sockets in the .NET Framework.

Overview of the Chapter

This chapter starts by presenting a general overview of sockets and continues with FTP and the project itself. In this chapter, you will find the following sections:

• "Working with Sockets": This section introduces sockets and explains how to use the System.Net.Sockets.Socket class and other related classes for network programming.

• "Understanding FTP": This section discusses the protocol for file transfer as specified in RFC959.

• "Creating an FTP Application Step by Step": This section covers a simple console application that is similar to the ftp.exe program included in the UNIX/Linux or Windows operating systems. This serves as an introduction to the chapter's FTP project.

• "Implementing the Project": This section contains a detailed discussion on the FTP client application with a Graphical User Interface (GUI).