There are several ways to extend the behaviour of existing code in Dynamicweb eCommerce.
In this section, we describe the following extensibility options:
With Price providers you can replace and extend the existing price structure of Dynamicweb eCommerce, and make calls to external systems to retreive a product price.
Sales discount providers
In short, Sales Discount Providers is to orders, what Price Providers is to products. It provides you with the possibility to invent your own discount types from scratch and apply them to an order, or to extend the built-in discount types in the Sales Discount module.
Checkout handlers are central part of the Shopping Cart v2 module and does all the logic of checking the customer out. Creating your own checkout handler will of course allow you to control the checkout step including page redirections and/or callbacks from other servers.