Unless I'm mistaken, smartcard (who sounds pretty confused) has an issue where s/he is using a desktop application which submits XML data to a remote website. Then, at the same time the hints that they have control of the desktop application:
Following is the setup that I have make in my desktop application
I'm going to assume that smartcard would like to see the XML data and may or may not have control of either desktop app or remote server and wants to the see the XML that is transmitted. I'm also going to assume that the XML data is submitted by HTTP on port 80.
OPTION 1
Install a web server with PHP locally on the desktop machine that runs the desktop ERP application. Find out what remote website it submits to (e.g., some.remote.example.com) and then make an entry in the HOSTS file on the desktop machine so that the desktop assumes that the remote site is hosted locally at 127.0.0.1:
127.0.0.1 some.remote.example.com
What this will do is cause the desktop machine to route any requests to some.remote.example.com to the local machine (e.g., localhost, aka 127.0.0.1) and, because you have installed a web server, you should be able to set up a PHP script to capture the XML submission. You may need to create a directory structure and/or virtual host configuration to match the URL exactly, but once you get your PHP script in the right place, put this in it:
file_put_contents("/path/to/dump/file.txt", print_r($_REQUEST, TRUE));
NOTE: this whole step is a LOT easier if you have control of the remote server because you don't have to install apache or php and you don't have to edit your hosts file and you don't have to set up any kind of directory structure or PHP files. You just do it on the remote webserver that receives these XML requests.
OPTION 2
Install wireshark on the desktop and use it to inspect the traffic to the server. It'll take some figuring out but it's a neat tool and it shouldn't be too hard.
Install wireshark on the