I’ve been reading and reading and I need help on the best way to approach 
this.  I need to develop web site and/or web service that accepts connections 
from a few “allowed” sites.  After It is determined that the incoming site is 
one of the “allowed” sites I need to read the information sent in (I would 
like this to be XML data that I can compare against a XSD file).  I the need 
to write that information to a database and send it off to another service 
(similar to PayPal), I then need to read the response from the “PayPal like” 
site and send that response to the original calling page.  I’m completely 
lost as to where to start.  
Thanks,
Tom