... architectures. In addition to managing business objects and processing the standard business logic, every interface method in the Façade validates the incoming arguments, authorizes the action for ... well as all cart maintenance methods: AddItem, RemoveItem, ReCalculate, ShippingStrategy. etc. The remaining types in this project are involved with shipping and shipping calculations. The ... these to their shopping cart. Their shopping carts can be managed by removing items and changing quantities. In the shopping cart, shipping costs are computed based on the shipping method selected....