In short, in the proxy pattern, one object is created by another only when the functionality of the first one is required. In this two-part series, I'm going to walk you through the key points of how to use this pattern with PHP 5, as well as how to apply it in different real-world situations.

They start with the creation of an expandable XML processor class that can be enhanced when additional functionality is needed. They use this class as a proxy for the requests and create a separate class (a normal XMLProcessor class) to perform the actual requests for the information - grabbing information from the loaded XML document.