E-Commerce Payment Processing with RabbitMQ

This project is a comprehensive learning exercise for RabbitMQ, implementing a payment processing system with progressive complexity levels from beginner to expert.

Project Overview

A payment processing gateway that handles transactions, refunds, and fraud detection. RabbitMQ is used for asynchronous processing to avoid blocking users during payment verification.

Tech Stack

• Node.js - Runtime environment
• NestJS - Web framework
• TypeORM - ORM for database operations
• PostgreSQL - Database
• RabbitMQ - Message broker
• Stripe - Payment gateway integration

Learning Progression

Beginner Level: Basic Payment Queuing

• Simple queue for payment requests
• Basic producer/consumer pattern
• JSON message handling

Intermediate Level: Work Queues

• Durable queues with manual acknowledgments
• Fraud detection with delays
• Audit trail logging
• Load balancing across workers

Advanced Level: Topic Exchanges

• Flexible routing with topic patterns
• Different handlers for different transaction types
• Priority queues for high-value transactions

Expert Level: Production Patterns

• Dead-letter queues for failed transactions
• RPC for real-time status checks
• Retry mechanisms
• Fault tolerance

Setup

Prerequisites

• Docker and Docker Compose
• Node.js 18+

Installation

1. Clone the repository

git clone <repo-url>
cd e-commerce-rabbitmq

2. Install dependencies

npm install

3. Start services with Docker Compose

docker-compose up -d

This will start:

• RabbitMQ on port 5672 (Management UI on 15672)
• PostgreSQL on port 5432

Access RabbitMQ Management UI: http://localhost:15672

• Username: admin
• Password: admin123

4. Create .env file

cp .env.example .env
# Update with your Stripe keys

5. Run the application

npm run start:dev

Project Structure

src/
├── payment/           # Payment processing module
│   ├── entities/      # TypeORM entities
│   ├── dto/           # Data transfer objects
│   ├── services/      # Business logic
│   └── queue/         # Queue handlers
├── rabbitmq/          # RabbitMQ configuration
│   ├── beginner/      # Basic queue pattern
│   ├── intermediate/  # Work queues
│   ├── advanced/      # Topic exchanges
│   └── expert/        # DLQ, RPC patterns
└── common/            # Shared utilities

API Endpoints

Payment Endpoints

• POST /payments - Create a payment
• GET /payments/:id - Get payment status
• POST /payments/:id/refund - Refund a payment

Learning Path

1. Start with Beginner - Understand basic queuing
2. Move to Intermediate - Learn about work queues and durability
3. Explore Advanced - Study topic exchanges and routing
4. Master Expert - Implement production-grade features

Useful Commands

# Development
npm run start:dev

# Build
npm run build

# Production
npm run start:prod

# View RabbitMQ Management
open http://localhost:15672

# Check containers
docker ps

Notes

This is a learning project focused on understanding RabbitMQ patterns. It includes:

• Multiple complexity levels
• Real-world scenarios
• Best practices
• Production considerations