Developer tasks to integrate Sitecore Commerce 8.0 powered by Commerce Server and Commerce Server 11.2 with Commerce Connect through the Cart Provider and pipelines.
This domain model details the minimum required information: 
Cart Domain Model
A cart has two unique composite keys:
- CartId (or ExternalCartId), ShopName. Some methods like LoadCart use this key to locate a cart.
- UserId, CustomerId, CartName, ShopName. Some methods like GetCarts and CreateCart use this key