Network Services: Protocols

Servers and clients operate according to a fixed set of rules called a protocol.

Perhaps you've heard this term used in the context of diplomacy. For instance, observing the "proper protocol" when meeting a queen might include "Do not speak to the queen unless she speaks to you first."

Similarly, for each network service, there is an agreed-upon set of rules according to which the client software and the server software will communicate.

For instance, Web browsers and Web servers communicate according to the Hypertext Transfer Protocol, or HTTP. Have you ever wondered why some Web addresses begin with the prefix http://? It is because this prefix specifies the protocol according to which the browser and the server will communicate. You don't need to specify it every time, because the browser will assume that you meant to include it and add it for you.

Similarly, you can transfer files between Internet computers using the File Transfer Protocol, or FTP. In this case, you simply execute an FTP client, and it will communicate the appropriate requests to an FTP server. Interestingly, your Web browser has an FTP client built-in. Thus, you may sometimes notice URLs that begin with the prefix ftp://. This indicates that your browser will send the request to an FTP server, rather than an HTTP server, and that the browser will communicate according to the FTP protocol rather than the HTTP protocol.

This chapter was written by Jeff Nyhoff and Joel Adams. Copy editing by Nancy Zylstra
©2005 Calvin University (formerly Calvin College), All Rights Reserved

If you encounter technical errors, contact computing@calvin.edu.