PRO-TEST is an imaginary on-line retailer committed to the business of selling stuff.
Web front end (not included here).
Java engine obtained from some big software company, such as IBM or Oracle (also not included here) with custom business logic plug-ins developed by the local IT staff.
Product: Something for sale.
Customer: A customer account.
Order: A purchase. Has a Customer and a list of purchased Items.
Item: A purchased Product, its purchase price, and an optional Promotion.
Promotion: A map of product IDs to discount prices.
"The lady doth PRO-TEST too much, methinks."