I have written a XML-Server in PHP5.
It is very easy to use. Just include the file and run the server.
It has some restrictions, it accepts only functions and static methods. you don't have to to change your code if your methods return a php type. (string, array, integer)
Example
<?php
$ws = new XML_RPC_Server();
$ws->registerFunction('getTime');
$ws->registerMethod('Product::getPrice');
$ws->registerMethod('Product::getDetail');
$ws->registerMethod('Product::getBinaryPicture');
$ws->run();
?>
Example Source,
http://www.pure-php.com/php/service.source.php
The Server
http://www.pure-php.com/php/xmlrpc.php.txt