Creating structural business rules at the outset will help guide the design throughout the rest of the sections. An example of this type of business rule not related to Amazon is A car may be driven by many drivers; each driver drives one or more cars. Each business rule should describe the entities involved, the relationship between the entities, and the optionality and plurality constraints for each entity. Try to make sure that you have created all the structural business rules required for each use case.

Use Case 1 - New Product Created by Seller

This occurs when a seller plans to sell a product it has not sold before:

1. The seller searches Amazons product list to determine if another seller is already selling the product.
2. If a different seller is already selling the product, a new listing is not required; the seller reuses the same listing.
3. If the product is not yet sold on Amazon, a new listing is created with the products name, description, price, and other relevant items. Every product added is linked to a product category (all categories are predefined by Amazon), for example, Computers, Electronics, Appliances, and similar.