Distributed Order Processing System

Overview

This project simulates an e-commerce-style distributed system that decouples order creation, processing, and status management. Using Redis as a queue, orders are processed asynchronously by a Go service, with inter-service communication via gRPC to ensure scalable, event-driven architecture.

---

Impact

• Mimics real-world backend systems used in online marketplaces and retail platforms.
• Demonstrates asynchronous communication and processing using a message queue (Redis).
• Provides hands-on understanding of gRPC, microservices, and inter-language service orchestration (Node.js ↔ Go).
• Highlights efficient status transition workflows (pending → processing → completed) in distributed environments.

---

Functionalities

• Create Orders via REST API (POST /orders)
• Push to Redis Queue with essential data (orderId, quantity)
• Process Orders asynchronously using Go service
• Update Status via gRPC to processing and later completed
• View All Orders using REST (GET /orders)
• MySQL Persistence for order lifecycle tracking

---

Technologies Used

Category	Technology
API Layer	Node.js, Express
Database	MySQL
Message Queue	Redis
Worker Service	Go
Communication	gRPC, RESTful
Containerization	Docker

---

Highlights

• Asynchronous queue-based processing with Redis
• Microservice architecture: loose coupling and high cohesion
• Language-agnostic gRPC interface between Go and Node.js
• Sequelize sync() ensures schema alignment without migrations
• Retries and health checks ensure robust startup via Docker Compose
• Modular codebase with separation of concerns (controllers, models, services)

---

Commands to Run the Project

Make sure Docker and Docker Compose are installed.

# Step 1: Clone the repo
git clone https://github.com/your-username/distributed-order-system.git
cd distributed-order-system

# Step 2: Start all services
docker-compose up --build

You should see:

• REST API on http://localhost:3000
• gRPC running on port 50051

---

Output Screenshots

Order Created

Fetch Orders

Output Logs

---

Sample Commands

Create an Order

curl -X POST http://localhost:3000/orders \
  -H "Content-Type: application/json" \
  -d '{
    "item": "Laptop",
    "quantity": 2,
    "price": 1299.99
  }'

Get All Orders

curl http://localhost:3000/orders

---

Notes

• The Redis queue only stores orderId and quantity for efficiency.
• Statuses (pending, processing, completed) are updated in MySQL through Sequelize.
• gRPC services are defined in .proto files and loaded using @grpc/proto-loader.
• Retry mechanisms ensure the Node service waits for MySQL and Redis before starting.
• The system is extensible to include features like email notifications, billing, etc.