Inventory management in LLD - Architecture Diagram

System Overview - Inventory management

This inventory management system helps businesses track product stock levels, update inventory after sales or restocking, and provide real-time availability information. It must handle many users updating and querying inventory simultaneously with accuracy and speed.

Architecture Diagram

User
  |
  v
Load Balancer
  |
  v
API Gateway
  |
  v
Inventory Service <-> Cache
  |
  v
Database

Components

User

client

Sends requests to check or update inventory

Load Balancer

load_balancer

Distributes incoming user requests evenly to API Gateway instances

API Gateway

api_gateway

Receives requests, handles authentication, routing to Inventory Service

Inventory Service

service

Processes inventory queries and updates business logic

Cache

cache

Stores frequently accessed inventory data for fast reads

Database

database

Stores persistent inventory records and updates

Request Flow - 10 Hops

User → Load Balancer

Load Balancer → API Gateway

API Gateway → Inventory Service

Inventory Service → Cache

Cache → Inventory Service

Inventory Service → Database

Database → Inventory Service

Inventory Service → Cache

Inventory Service → API Gateway

API Gateway → User

Failure Scenario

Component Fails:Database

Impact:Inventory updates fail; reads may serve stale data from cache

Mitigation:Use database replication for failover; serve reads from cache with warning; queue updates for retry

Architecture Quiz - 3 Questions

Which component handles user authentication before processing inventory requests?

A API Gateway

B Load Balancer

C Inventory Service

D Cache

Design Principle

This design uses a cache to speed up frequent inventory reads and reduce database load. The load balancer and API Gateway provide scalability and security. The database stores persistent data with replication for reliability. This layered approach balances speed, accuracy, and fault tolerance.