OrderFlow – Real-Time Distributed Inventory System

OrderFlow is a real-time inventory management system built with FastAPI, Redis Pub/Sub, and Supabase. It demonstrates how multiple distributed services (store servers) can synchronize stock data in real time using an event-driven architecture. This project is ideal for understanding distributed systems, microservices, and real-time data updates.

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Features

• Real-Time Stock Synchronization Stock changes in one instance are instantly propagated to all other instances via Redis Pub/Sub.

• Event-Driven Architecture Uses Redis Pub/Sub to handle updates asynchronously, keeping multiple nodes in sync.

• Microservice-Ready Design Separates concerns using FastAPI routers, Redis messaging, and Supabase as the database.

• RESTful API Endpoints

  • Add a product
  • Update stock
  • View all products

• Distributed System Simulation Can run multiple FastAPI instances on different ports to simulate multiple stores sharing inventory data.

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Tech Stack

• Python 3.11+
• FastAPI – API framework
• Redis – Pub/Sub for event-driven communication
• Supabase – PostgreSQL database backend
• Docker (optional) – To simulate containerized deployments

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Project Structure

backend/
├── app/
│   ├── __init__.py
│   ├── main.py            # FastAPI entrypoint
│   ├── redis_pubsub.py    # Redis Pub/Sub utilities
│   └── routers/
│       ├── __init__.py
│       └── inventory.py   # Inventory API routes
├── database.py            # Supabase database functions
├── .env                   # Environment variables
└── ...

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Setup Instructions

1. Clone the repository

git clone <your-repo-url>
cd orderflow/backend

2. Install dependencies

pip install -r requirements.txt

3. Configure environment

Create a .env file with your Supabase credentials:

SUPABASE_URL=your_supabase_url
SUPABASE_KEY=your_supabase_key
REDIS_URL=redis://localhost:6379/0

4. Start Redis

Run Redis server:

redis-server

5. Run FastAPI

Single instance:

uvicorn app.main:app --reload --port 8000

Multiple instances (simulate distributed nodes):

uvicorn app.main:app --reload --port 8001
uvicorn app.main:app --reload --port 8002

6. Test API

• Open http://127.0.0.1:8000/docs
• Add a product, update stock, and check synchronization across instances.

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How It Works

1. Adding/Updating Products

   • FastAPI endpoints update Supabase.
   • The publish_update() function sends a message to Redis.

2. Redis Pub/Sub

   • All FastAPI instances subscribe to the inventory_updates channel.
   • When a message is published, all nodes update their local state immediately.

3. Distributed Simulation

   • Running multiple FastAPI instances simulates multiple stores connected to the same Redis and database.
   • Demonstrates event-driven architecture, real-time sync, and distributed system principles.

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Future Improvements

• Add in-memory caching for faster reads per node.
• Implement Docker Compose to containerize nodes and Redis.
• Add monitoring with Prometheus and Grafana.
• Support order processing and customer checkout in real time.

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License

MIT License – free to use and modify.