Simplified Order Processing with Apache's mod_qs2ssi
By Mitch Wyle
Server-side includes (SSI) are special directives that are embedded as part of your HTML documents. SSI-enabled Web servers automatically replace these directives with computed values. SSI codes specify things like the last modification time of the document, its filename or URL, and other information from environment variables. SSI also lets you include standard inline headers, footers, and other common information that is stored in separate files. This function is the main and most popular purpose of SSI. SSI even lets the HTML in your document execute arbitrary UNIX commands, making the output of these commands appear as part of your document.
Apache is the most-used and most actively developed Web server in current use. Out of the box, Apache comes with the standard mod_include module enabled. Many of us use this module to insert standard headers and footers into our HTML pages using the <!--#include --> construct. However, the module provides many functions in addition to the simple #include parsing. You can set variables, create if-then-else conditional areas of an HTML file, perform string manipulation, and even launch external system commands just as you can in CGI. The documentation that comes with the mod_include module isn't very clear, and the syntax itself is also quite arcane. Regardless, it's a powerful system and simple to use once you get used to it. For this reason, it's more efficient and easier to take advantage of the Apache mod_include SSI capabilities directly in HTML documents instead of writing CGI application programs.
