Why library management tests CRUD design in LLD - Architecture Impact

System Overview - Why library management tests CRUD design

This system manages a library's collection of books and user records. It supports creating, reading, updating, and deleting (CRUD) data for books, members, and loans. The key requirement is to ensure data consistency and easy access for library staff and users.

Architecture Diagram

User
  |
  v
Load Balancer
  |
  v
API Gateway
  |
  v
Library Management Service
  |        |
  v        v
Cache    Database

Components

User

client

Library staff or members who interact with the system

Load Balancer

load_balancer

Distributes incoming requests evenly to prevent overload

API Gateway

api_gateway

Handles request routing, authentication, and rate limiting

Library Management Service

service

Processes CRUD operations for books, members, and loans

Cache

cache

Stores frequently accessed data to reduce database load

Database

database

Stores persistent data about books, members, and loans

Request Flow - 11 Hops

User → Load Balancer

Load Balancer → API Gateway

API Gateway → Library Management Service

Library Management Service → Cache

Cache → Library Management Service

Library Management Service → Database

Database → Library Management Service

Library Management Service → Cache

Library Management Service → API Gateway

API Gateway → Load Balancer

Load Balancer → User

Failure Scenario

Component Fails:Database

Impact:CRUD write operations fail; reads may serve stale data from cache

Mitigation:Use database replication for failover; cache serves read requests temporarily

Architecture Quiz - 3 Questions

Which component handles user authentication before processing CRUD requests?

A API Gateway

B Load Balancer

C Cache

D Database

Design Principle

This design shows how CRUD operations in a library system use caching to improve read performance and a layered architecture to ensure scalability and reliability.