I have answered you in the email, so I will close this thread.
However, I will repeat what I have stated in the email. Depending on your particular requirements, you can leverage the different extension points of the system, namely:
• Fully Exposed API – You can use the API to pull/push information from/to external applications. You can use ASP.NET WebForms or ASP.NET MVC to create controls and controllers to do all sort of actions ranging from catalog related action to payment processing and inventory maintenance (link here)
• Web Services – Sitefinity also has a rich web API for cross platform integration (link here). One of our senior developers has added additional wrapper for easier API calls (link here)
• Ecommerce events, a.k.a. processing hooks – The processing hooks allow you to execute custom code when a specific event occurs, i.e. order is processes, shopping cart is updated, order has changed and etc.(link here)
Also, Sitefinity support claim based authentication to support advanced single sign on scenarios if you need that for your integration scenario. Here is a good article on how to achieve that (link here).