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LLDsystem_design~12 mins

Product, Cart, Order classes in LLD - Architecture Diagram

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System Overview - Product, Cart, Order classes

This system models a simple shopping process using three main classes: Product, Cart, and Order. Users can add products to their cart, review the cart, and place an order. The system tracks product details, cart contents, and order status.

Architecture Diagram
User
  |
  v
Cart <--> Product
  |
  v
Order
  |
  v
Payment Service (optional)
Components
User
actor
Interacts with the system to browse products, add to cart, and place orders
Product
class
Represents items available for purchase with details like name, price, and stock
Cart
class
Holds selected products and quantities before order placement
Order
class
Represents a finalized purchase with order details and status
Payment Service
external_service
Handles payment processing for orders (optional in this model)
Request Flow - 6 Hops
User → Product
User → Cart
User → Cart
User → Order
Order → Payment Service
Order → User
Failure Scenario
Component Fails:Cart
Impact:Users cannot add or view products in their cart, blocking order placement
Mitigation:Implement local session storage or retry logic; notify users of temporary issues
Architecture Quiz - 3 Questions
Test your understanding
Which class holds the products a user wants to buy before placing an order?
AOrder
BCart
CProduct
DPayment Service
Design Principle
This design separates concerns by using distinct classes for products, cart, and orders, enabling clear responsibilities and easier maintenance. It models a common e-commerce flow where users select products, review their cart, and place orders, reflecting real-world shopping behavior.