I would suggest looking into using a SOAP extension, which in my opinion is ideal for this scenario. Here are a few links that describe the process.
http://msdn.microsoft.com/en-us/magazine/cc164007.aspx
https://ebay.custhelp.com/cgi-bin/ebay.cfg/php/enduser/std_adp.php?p_faqid=350
http://www.codeproject.com/KB/webservices/efficientsoapextension.aspx
Garett
2010-10-07 07:13:49