XML-RPC (eXtensible Markup Language Remote Procedure Call) is a method of sharing messages between client and server. It was developed to deal with the limitations of XML/HTTP. XML-RPC is a lightweight protocol intended for exchanging structured information in a decentralized, distributed environment. The framework has been designed to be independent of any particular programming model and other implementation-specific semantics.
http://www.xmlrpc.com/
http://www.sitepoint.com/article/827/1/
http://davenet.userland.com/1998/07/14/xmlRpcForNewbies