This tutorial teaches you, step-by-step, how to build an XML-RPC client in PHP using the XML-RPC library written by Edd Dumbill. It covers each of the PHP classes you will be using, and how they fit together to form the final client.
A primer is included to introduce the basics of the XML-RPC specification. The primer provides enough information to work with the XML-RPC library. If you want to learn more about the XML-RPC specification see http://www.xmlrpc.com.