Wow, now this is one old library i have forgotten about.
I wrote this somewhere around 2001-2002 when i was still using PHP. It's the xmlRPC protocol ported to PHP at a time when things like web-services & SOAP didn't even exist yet.
My personal twist on this library was the added feature of callbacks. This made it possible for one server to instantiate an xmlRPC call to another distant server, and the distant server could then request additional information. Like this both servers could now get a conversation going on, and exchange various information, files, do synchronization, etc..
There was also a small VB6 sample included which demonstrated how to log into the distant xmlRPC endpoint from a desktop application and then retrieve/manipulate user information.
In the meantime i have moved on to Microsoft & the C#/.NET platform since 2003. And am now mostly working with C# 5, .NET 4.5, and MVC 4, when I'm not doing front-end development in HTML/CSS/JS.
However seeing that there are still active downloads going on on this old PHP project (11 years after being published !) and that there where some issues to be taken care of, i decided i should maybe brush off my PHP skills a bit, and do at least one final update to this library.
..thus the existence of this page :)