[Zope] Help for integration of E-shop

[Gitte Wange]

Hello,

I have been working on integrating a web shop in our zope site.
We are using a payment gateway called "Cashcow" and it works great. At
least it registers the orders and payments :-)))

It works this way:
User enter his/hers date in a html form. (including cart number etc). The
html form calls the payment gateway with the correct parameters.
If the card was accepted the shop returns one page (you define this in the
mangement interface). If there were errors, it returns another page.

Now on this 'ok_page' I want to do some things if everything went ok
(creation of a zope 'Order' object for instance). But ... this gateway only
returns the REQUEST variables that it is set up to in the system (not
something you can configure).
So I cannot parse the logged_in user's username. And at the 'ok_page' it
shows, no user is logged in.

So my question is:
Are there anybody else out there who has a payment gateway that works
something like described above and know a different workaround ??

TIA,
Gitte Wange