At the request of a client I spent a few hours reviewing your script this week. One question. Is its environment open. For instance can I add a module to it without banging into an encoded core file? Of particular interest are the following:
 
Ability to hook gateway returns to pass data to other apps for the purpose of fulfillment and the ability to get to functionality that would allow me to inhibit display of products based on outside criteria.
 
If it is fairly open in these areas then this might just be a splendid platform for programmers to tailor to specific vertical markets that have more specific options than just a pass along.
 
Here is an example. The customer who asked me about this is a hosting and design company. A purchase could consist of a provisioning request, a particular application setup and some custom design. In this case I would want to hook the gateway return as a signal to proceed or not. If approved I want to get the order details from this db which is no big deal. Then I do the provisioning via another script. What I don't know is if your architecture will allow me to add a control module to its CP to handle this product type or whether the result from the gateway occurs in open code or zend.
 
I hope this makes sense and we can work together because I really like your shop functions and I would rather buy that functionality rather than re-invent the wheel, but that is only possible if extending it is possible.

Hi,
 
The architecture is quite extensible and you can easily add your own modules.
ViArt Shop contains 97% of open source code; the remaining 3% of the code is encoded within the library ./includes folder.
Within 97% of open code it is possible to fully customize ViArt to your individual needs.
 
Regards,
ViArt Support Team