Cache_Lite is one of the fast, light and reliable cache system for PHP. It's an extremely easy and small learning curve system to work with. This post will try to make you a light introduction to PHP Cache_Lite.

He starts from the beginning - installing the package through the PEAR installer and setting up a basic configuration for a new Cache_Lite object in a script. Using this object you can test for the existence of a cached value or set a new one. The configuration allows you to define the "time to live" before the records expire.

As your site traffic grows it takes longer and longer to generate a dynamic page from sending multiple queries to a database. One possible solution to limit queries is to cache the result of each query that is needed, or to have a complete full page cache for your site.

They look at the two ways I mentioned - the Cache_Lite PEAR package and the APC extension (that will soon be included by default in the stable PHP releases). Bits of code are provided for each showing how to get them set up and get them working inside of your application.

In the good old days when building web sites was as easy as knocking up a few HTML pages, the delivery of a web page to a browser was a simple matter of having the web server fetch a file. [...] Then dynamic web pages came along and spoiled the party by introducing two problems: a delay for processing and a check of the file's age before it's sent to the browser.

They talk about what caching can do for you, what you can do (both server and client side) to prevent caching, working with the headers sent from and back out to the browser, using output buffering, partial caching and using PEAR::Cache_Lite in your application.

Every time a request hits your server, PHP has to do a lot of processing, all of your code has to be compiled & executed for every single visit. Even though the outcome of all this processing is often identical for both visitor 21600 and 21601. So why not save the flat HTML generated for visitor 21600, and serve that to 21601 as well? This will relieve resources of your web server and database server because less PHP often means less queries.

The Cache_Lite PEAR package makes it simple to cache both entire pages or just small parts. He shows the installation (through aptitude on Ubuntu) and how to use it in a simple code example that stores the cached copy to the local drive for a given amount of time.