Programming PHP

Example 9-8. Caching dynamic buttons
A Faster Cache
Example 9-8 is still not quite as quick as it could be. There is a more advanced caching
technique that completely eliminates PHP from the request once an image has
been generated.
First, create a buttons directory somewhere under your web server’s DocumentRoot
and make sure that your web server user has permissions to write to this directory.
For example, if the DocumentRoot directory is /var/www/html, create /var/www/html/
buttons.
Second, edit your Apache httpd.conf file and add the following block:
ErrorDocument 404 /button.php
This tells Apache that requests for nonexistent files in the buttons directory should be
sent to your button.php script.
Third, save Example 9-9 as button.php. This script creates newbuttons, saving them
to the cache and sending them to the browser. There are several differences from
Example 9-8, though. We don’t have form parameters in $_GET, because Apache handles
error pages as redirections. Instead, we have to pull apart values in $_SERVER to
find out which button we’re generating. While we’re at it, we delete the '..' in the
filename to fix the security hole from Example 9-8.
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