Bazar.com - World's Smallest Book Store

Bazar.com is a simple bookstore web application designed with a two-tier microservices architecture. The application supports basic functionalities for book management, including search, viewing, and purchasing books.

Project Description

This project employs a two-tier architecture with microservices. The application consists of the following main components:

1. Frontend Service: Manages user requests and interacts with backend services (tested via Postman).
2. Catalog Service: Manages the book inventory, including details and stock availability.
3. Order Service: Processes purchase requests and updates the stock for each order.

Features

• Search: Search books by topic and view available options.
• Info: Get detailed information about specific books, such as stock and price.
• Purchase: Purchase a book, which updates stock and order details.
• API Documentation: Interactive API documentation via Swagger UI.
• Caching: Redis is used to cache frequently accessed book information to improve performance.
• Load Balancing: Load balancer implemented using Nginx to distribute requests evenly across instances of Catalog and Order services.

Technologies Used

• Node.js with Express.js for backend services.
• Sequelize ORM for database management.
• SQLite as a lightweight database.
• Redis for caching to enhance performance.
• Nginx for load balancing.
• Swagger UI for API documentation.
• Docker for containerization.

Architecture Overview

The application follows a microservices architecture:

• Frontend Service:

  • Receives client requests and relays them to Catalog and Order services through REST APIs.

• Catalog Service:

  • Manages book catalog and stock.
  • Caches frequently accessed data using Redis to reduce database calls.

• Order Service:

  • Processes book purchases.
  • Updates the stock in the catalog and records orders.

• Nginx Load Balancer:

  • Distributes incoming requests across instances of Catalog and Order services to improve scalability and handle high traffic.

REST API Endpoints

Catalog Service

1. GET /catalog/search/:topic - Retrieves a list of books by topic.

   [
     { "id": 1, "title": "How to get a good grade in DOS in 40 minutes a day" },
     { "id": 2, "title": "RPCs for Noobs" }
   ]

2. GET /catalog/info/:itemNumber - Retrieves detailed information for a specific book.

   {
     "title": "RPCs for Noobs",
     "quantity": 5,
     "price": 50
   }

3. PUT /catalog/update/:itemNumber - Updates book details, including cost or quantity.

Order Service

1. POST /order/purchase/:id - Processes a book purchase and reduces stock.

   {
     "message": "Book purchased successfully",
     "order": {
       "bookId": 1,
       "quantity": 1
     }
   }

2. PUT /order/update-stock/:id - Updates the stock for a specific book.

Database Schema

Catalog Table

Column	Type	Description
id	INTEGER	Primary key for each book
title	TEXT	Title of the book
quantity	INTEGER	Quantity in stock
price	REAL	Price of each book
topic	TEXT	Topic of the book

Orders Table

Column	Type	Description
id	INTEGER	Primary key for each order
bookId	INTEGER	ID of the book ordered
quantity	INTEGER	Quantity purchased

Caching and Load Balancing

Caching with Redis

• Frequently accessed data, such as book details and availability, are stored in Redis to improve response time and reduce load on the SQLite database.
• Redis caching is applied on endpoints like /catalog/info/:itemNumber to return results faster for repeated requests.

Load Balancing with Nginx

• Nginx is configured as a load balancer to evenly distribute requests across multiple instances of the Catalog and Order services.
• This setup allows the application to handle higher traffic efficiently, ensuring better uptime and scalability.

Installation & Setup

1. Clone the repository:

   git clone https://github.com/your-username/bazar-com.git
   cd bazar-com