SSI and ESI

If you followed the introductory chapter carefully, then you will know that SSI and its successor, ESI, were invented to replace the client-side mechanism framesets with a server-side counterpart. There have been multiple reasons for this:

• Framesets required more requests.
• Framesets could not use take advantage of the parent's base styling or structure.
• Framesets in general make the website inconsistent.

Naturally, the first thing that changed was the <frameset> element. Since the first impression was to keep this addition hidden on the client in case the backend did not process it properly, another mechanism had to be chosen.

A special comment was born:

<!--#include virtual="../quote.txt" -->

Some web servers require a special kind of file extension for static files, while others require a configuration for SSI to be active.

SSI

The common SSI directives that are supported by pretty much all web servers ...