June 2000
Intermediate to advanced
470 pages
14h 14m
English
Content preview from CGI Programming with Perl, 2nd EditionBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Chapter 2. The Hypertext Transport Protocol
The Hypertext Transport Protocol (HTTP) is the common language that web browsers and web servers use to communicate with each other on the Internet. CGI is built on top of HTTP, so to understand CGI fully, it certainly helps to understand HTTP. One of the reasons CGI is so powerful is because it allows you to manipulate the metadata exchanged between the web browser and server and thus perform many useful tricks, including:
Serve content of varying type, language, or other encoding according to the client’s needs.
Check the user’s previous location.
Check the browser type and version and adapt your response to it.
Specify how long the client can cache a page before it is considered outdated and should be reloaded.
We won’t cover all of the details of HTTP, just what is important for our understanding of CGI. Specifically, we’ll focus on the request and response process: how browsers ask for and receive web pages.
If you are interested in understanding more about HTTP than we provide here, visit the World Wide Web Consortium’s web site at http://www.w3.org/Protocols/. On the other hand, if you are eager to get started writing CGI scripts, you may be tempted to skip this chapter. We encourage you not to. Although you can certainly learn to write CGI scripts without learning HTTP, without the bigger picture you may end up memorizing what to do instead of understanding why. This is certainly the most challenging chapter, however, because we ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.