Student Organization Web Service

Server Side Includes and XBitHack

Server Side Includes, more commonly referred to as SSI, provide a means to add dynamic content to existing HTML documents. SSI are directives that are placed in HTML pages, and evaluated on the server while the pages are being served. They let you add dynamically generated content to an existing HTML page, without having to serve the entire page via a CGI program, or other dynamic technology.

The decision of when to use SSI, and when to have your page entirely generated by some program, is usually a matter of how much of the page is static, and how much needs to be recalculated every time the page is served. SSI is a great way to add small pieces of information, such as the current time. But if a majority of your page is being generated at the time that it is served, you may want to look for some other solution.

For quite a bit more information and a bit of a tutorial on SSI check out the Apache group's SSI Tutorial.

So where does XBitHack fit into this? XBitHack is a directive your web server maintainers have turned on in the web server. This is how you tell the web server that a particular HTML document has SSI in it. Why not just assume all pages have SSI? Good question. It's answered in the above SSI Tutorial.

So how do you use XBitHack to tell the web server your page is using SSI? This gets a little bit into unix file permissions. The FAQ has a section that talks a little about unix file permissions. For XBitHack all you really need to know is this:

754	Page contains only static SSI calls; calls that include page headers and footers.
744	Page contains both static and dynamic SSI calls; calls that include page headers and footers and other things like news feeds.
644	Page contains no SSI calls.

Do I have to deal with these file permissions? No. If you don't though you MUST use the extension ".shtml" to tell the server that the file contains SSI.