OrderSaga - Distributed Transaction System (Saga Pattern)

Distributed Saga Pattern Engine

OrderSaga is a distributed transaction orchestration system designed to solve the consistency problem in microservices. It implements the Choreography-based Saga Pattern to ensure that multi-service operations (Order -> Inventory -> Payment) are either 100% completed or gracefully rolled back using compensating transactions.

---

🚀 Quick Start

Launch the entire cluster in 2 steps:

# 1. Start Infrastructure (RabbitMQ + Postgres)
docker-compose up -d

# 2. Start Services (Order, Inventory, Payment, UI)
npm install && npm run dev

Detailed Setup: See GETTING_STARTED.md.

---

📸 Demo & Architecture

Real-time Event Stream Dashboard

Monitoring transactions as they flow through the RabbitMQ bus.

System Architecture

Decoupled microservices communicating via an asynchronous event bus.

Saga Failover & Rollback

Visualizing the automated undo logic when a payment step fails.

Deep Dive: See ARCHITECTURE.md for Decision Logs and HLD.

---

✨ Key Features

• ⚡ Choreography-based Saga: Decentralized transaction state management.
• 🔄 Automatic Rollbacks: Built-in compensation logic for failed payments.
• 📦 Idempotent Consumers: Safe message redelivery without data duplication.
• 📊 Transaction Telemetry: Real-time observability of event status.

---

🏗️ The Transaction Journey

Understanding how a user click propagates through the distributed system:

1. Command: User initiates order (creates PENDING record).
2. Notification: ORDER_CREATED event published to RabbitMQ.
3. Reservation: Inventory service marks stock as RESERVED.
4. Charge: Payment service attempts credit card auth.
5. Completion: On success, order marks as CONFIRMED. On failure, triggers compensation.

---

📚 Documentation

Document	Description
System Architecture	Deep dive into Saga vs Orchestration and LLD.
Getting Started	Step-by-step setup and env configuration.
Failure Scenarios	Resilience testing and chaos engineering results.
Interview Q&A	Executive summary and system design pitch.

---

🔧 Tech Stack

Component	Technology	Role
Messaging	RabbitMQ	Asynchronous Event Bus.
Services	Node.js / TS	Core Microservices logic.
Database	PostgreSQL	Distributed Persistent State.
Interface	Next.js 14	Transaction Monitoring UI.

---

👤 Author

Harshan Aiyappa
Senior Full-Stack Hybrid Engineer
GitHub Profile

---

📝 License

This project is licensed under the MIT License - see the LICENSE file for details.