Custom Session Handlers in PHP4

This document describes how to customize the session handlers in PHP4. We will
provide examples of how to write a fully functional session handler that works
with DBM files and one that works with a MySQL database.

New to PHP4 was a set of native session handling functions which was badly
missing from PHP3. By default, each session is stored as a separate file
in your temporary directory (eg. /tmp in Unix). This may or may not be
appropriate depending on your requirements. For example, if you have a bunch
of web/PHP servers on different machines, you can’t easily share sessions between
them (well you could save the sessions on an NFS share but that would be
slow). Another problem is that you potentially have thousands or even millions
of session files cluttering up your file system
(you run a big site right <grin>).

Fortunately for us, the developers of PHP4 were forward thinking enough
(thanks!) to provide the ability for users like you and me to extend the
session handling routines.

This document is written to explain these session handlers a bit and to
provide two working examples of how you can extend the session handlers.
Our first example will be to make the session handlers save session data
into DBM files. Our second example will have our sessions save into a
MySQL database.

Before you proceed, download the attachment and extract it into your
web document directory.