Order Processor – gRPC + RabbitMQ (Minimal)

A minimal distributed system demo that uses:

• gRPC for synchronous service-to-service calls
• RabbitMQ as a message broker for asynchronous events
• Docker Compose for one-command startup

This project simulates an order → payment → notification workflow.

Architecture

Client → Order Service (gRPC) → Payment Service (gRPC) → RabbitMQ → Notification Service

• Order Service – Accepts CreateOrder requests and calls Payment Service via gRPC.
• Payment Service – Processes payments and publishes PaymentCompleted or PaymentFailed events to RabbitMQ.
• Notification Service – Listens to RabbitMQ events and logs a simulated “email sent” message.
• RabbitMQ – Event broker for communication between Payment and Notification services.

Tech Stack

• Node.js 20
• gRPC + Protobuf
• RabbitMQ 3-management
• Docker Compose
• Built-in retry/backoff for broker connections

Getting Started

1. Prerequisites

• Docker installed
• Docker Compose installed
• Port 5672 (RabbitMQ) and 50051-50052 free on your machine

2. Clone the repo

git clone https://github.com/phamphihungbk/orderflow.git
cd orderflow

3. Build & start services

docker compose up --build

• Starts RabbitMQ, Order Service, Payment Service, Notification Service
• RabbitMQ UI → http://localhost:15672 (user: guest, pass: guest)

You’ll see logs like:

[order] gRPC listening on 50051
[payment] gRPC listening on 50052
[notify] Connected. Waiting for messages in 'payments'

4. Run the client

Open a second terminal (still in project root):

docker compose run --rm client

Expected output:

Client response for A-1001: { status: 'PAID', message: 'Order A-1001: Payment captured' }
Client response for A-1002: { status: 'FAILED', message: 'Order A-1002: Card declined' }

5. Check service logs

Order Service:

[order] CreateOrder received: { order_id: 'A-1001', ... }
[order] Payment result: PAID - Payment captured

Payment Service:

[payment] Processing order A-1001 for $49.99
[payment] Published to 'payments': {...}

Notification Service:

[notify] Email sent to alice@example.com: Your order A-1001 is PAID.
[notify] Email sent to bob@example.com: Your order A-1002 FAILED.

6. Stop all services

docker compose down -v

RabbitMQ Management UI

Access:

http://localhost:15672

Login:

Username: guest
Password: guest

You can inspect the payments queue and see messages when running the client.

Project Structure

proto/                  # Protobuf definitions
services/
  order-service/        # gRPC server for orders
  payment-service/      # gRPC server for payments + publishes to RabbitMQ
  notification-service/ # Worker that consumes RabbitMQ messages
client/                 # Simple script to call Order Service
docker-compose.yml
README.md

Demo