UML

Design Notes

• Using HashMap in Cart to provide easy and fast access and updates.
• Using Product Validator to avoid rewriting validation functions (Used in both Cart and Checkout Service to proved initial and last Checks on Qunatity and ExpiryDates).

Assumptions

• Products are concrete instances of classes ( Categories like Food and Electrcial Devices ), as this is a simulation for the customer side only and not the func. of adding new product categories.
• Shipping Service has its own attribute (Cost per Kg) which is used for calculation.
• Validations (checking expiry and quantity) occur both at the Cart and Checkout stages to ensure mistakes are caught early and to provide fast feedback for customers from the cart info page.