💳 Distributed Payment Orchestrator

A production-grade payment processing system built with Node.js and microservices. It provides reliable asynchronous payment execution with retries, rate limiting, circuit breakers, and idempotent processing.

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✨ Features

• Asynchronous payment processing with BullMQ
• JWT authentication
• Redis-backed rate limiting
• Circuit breaker for fault tolerance
• Automatic retries with exponential backoff
• Dead Letter Queue (DLQ)
• Duplicate payment protection
• Structured logging with Winston
• Health check endpoints

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🏗️ Architecture

Client
  │
  ▼
API Gateway
  │
  ▼
Payment Service
  ├── PostgreSQL
  ├── Redis + BullMQ
  ▼
Payment Worker
  ▼
External Payment Provider

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🛠 Tech Stack

• Node.js
• Express.js
• PostgreSQL
• Redis
• BullMQ
• JWT
• Opossum (Circuit Breaker)
• Winston

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🚀 Quick Start

# Clone repository
git clone <repository-url>
cd distributed-payment-orchestrator-system

# Install dependencies
npm install

# Start PostgreSQL and Redis
docker-compose up -d

# Start services
npm run api-gateway
npm run payment-service
npm run start-worker

Verify:

curl http://localhost:3000/health
curl http://localhost:4000/health

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📁 Project Structure

payment-orchestrator/
├── api-gateway/
├── payment-service/
├── shared/
├── logs/
├── docker-compose.yml
└── package.json

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🔄 Payment Flow

Client
  ↓
API Gateway
  ↓
Payment Service
  ↓
PostgreSQL (PENDING)
  ↓
BullMQ Queue
  ↓
Worker
  ↓
Payment Provider
  ↓
SUCCESS / FAILED

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📚 Documentation

Detailed documentation is available in separate files:

File	Description
QUICK_START.md	Setup and local development
ARCHITECTURE.md	System design and patterns
API.md	API reference and examples
DEPLOYMENT.md	Deployment instructions
SECURITY.md	Security considerations

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🔑 Key Design Patterns

• Microservices Architecture
• Circuit Breaker
• Queue-based Asynchronous Processing
• Idempotency
• Retry with Exponential Backoff
• Dead Letter Queue
• Rate Limiting

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📊 Observability

• Structured logging with Winston
• Health check endpoints
• Worker success/failure events
• Queue monitoring
• Error tracking

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📝 Environment Variables

Create a .env file:

cp .env.example .env

Important variables:

• JWT_SECRET_KEY
• POSTGRES_DB_PASSWORD
• REDIS_URL
• PAYMENT_SERVICE_URL

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🚀 Future Improvements

• Prometheus metrics
• OpenTelemetry tracing
• Webhooks
• TypeScript migration
• Kubernetes deployment

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📄 License

ISC License.