📘 Smart Library System – Monolithic Architecture #

Overview #

The Smart Library System (Monolithic Version) is a single, unified application that handles all core functionalities: managing users, books, and book loans. This system is ideal for simple deployments where all components are tightly coupled, sharing the same runtime and database.

🧩 Functional Modules #

1. User Management Module #

• Register a user (students/faculty).
• Update user profile.
• Retrieve user info.

2. Book Management Module #

• Add/update/remove books.
• View book availability.
• Search books by title, author, or genre.

3. Loan Management Module #

• Issue books to users.
• Return books.
• View active/past loans.

🛢️ Unified Database Schema #

All modules interact with this shared relational database, typically PostgreSQL or MySQL.

🔄 Internal Communication #

• All module calls happen via function calls or internal classes.
• Tight coupling between modules.
• No network-based interaction — all components reside in the same codebase and memory space.

🧪 Example API Documentation (REST Endpoints) #

Here’s how external clients (like CLI tools or a potential frontend) interact with the system.

🔹 User Endpoints #

POST /api/users #

Create/register a new user.

{
  "name": "Alice Smith",
  "email": "[email protected]",
  "role": "student"
}

GET /api/users/{id} #

Fetch user profile by ID.

🔹 Book Endpoints #

POST /api/books #

Add a new book.

{
  "title": "Clean Code",
  "author": "Robert C. Martin",
  "isbn": "9780132350884",
  "copies": 3
}

GET /api/books?search=clean #

Search for books by title, author, or keyword.

🔹 Loan Endpoints #

POST /api/loans #

Issue a book to a user.

{
  "user_id": 1,
  "book_id": 42
}

POST /api/returns #

Return a borrowed book.

{
  "loan_id": 1001
}

GET /api/loans/{user_id} #

View loan history for a user.

⚠️ Limitations of Monolithic Design #

• Hard to scale individual components independently.
• Tight coupling makes it difficult to change or test modules in isolation.
• Single point of failure: one bug can crash the entire app.
• Deployment of small changes requires redeploying the whole system.