Online Orders System — Microservices

Project Structure

MVC/
├── docker-compose.yml
├── user-service/
│   ├── Dockerfile
│   ├── package.json
│   └── src/
│       ├── app.js
│       ├── index.js
│       ├── controllers/
│       │   └── user.controller.js
│       ├── routes/
│       │   └── user.routes.js
│       ├── services/
│       │   └── user.service.js
│       └── models/
│           └── User.js
├── order-service/
│   ├── Dockerfile
│   ├── package.json
│   └── src/
│       ├── app.js
│       ├── index.js
│       ├── controllers/
│       │   └── order.controller.js
│       ├── routes/
│       │   └── order.routes.js
│       ├── services/
│       │   ├── order.service.js
│       │   └── rabbitmq.service.js
│       └── models/
│           └── Order.js
└── notification-service/
    ├── Dockerfile
    ├── package.json
    └── src/
        ├── app.js
        ├── index.js
        ├── controllers/
        │   └── notification.controller.js
        ├── routes/
        │   └── notification.routes.js
        ├── services/
        │   ├── mailer.service.js
        │   ├── notification.consumer.js
        │   └── notification.service.js
        └── models/
            └── Notification.js

---

Architecture

This project follows a hybrid architecture:

• System level: Microservices architecture with event-driven communication.
• Service level: MVC pattern inside each microservice.

MVC Mapping Per Service

• Model: Mongoose schemas in each models/ folder.
• Controller: HTTP handlers in each controllers/ folder.
• View: JSON API responses returned by controllers (API-style MVC).
• Routing and orchestration: Express routes in each routes/ folder, business/integration logic in each services/ folder.

Services

Service	Port	Database	Role
user-service	3001	usersdb	Manages user registration and lookup
order-service	3002	ordersdb	Creates orders, publishes events to RabbitMQ
notification-service	3003	notificationsdb	Consumes RabbitMQ events, stores notifications
rabbitmq	5672	—	Message broker (queue: order-events)

---

Requirements Covered

• Each microservice has its own independent MongoDB database.
• order-service and notification-service communicate via RabbitMQ:
  • order-service publishes an order.created event on every new order.
  • notification-service consumes events and stores a notification record.
• All services and databases are containerized with Docker.
• The entire system runs with a single docker compose up command.
• Architectural pattern followed:
  • Microservices + Event-Driven at system level.
  • MVC within each individual microservice.

---

Prerequisites

• Docker Desktop installed and running

---

Run the System

From the MVC folder:

docker compose up --build -d

To stop:

docker compose down

To stop and remove all data volumes:

docker compose down -v

---

API Reference

User Service — http://localhost:3001

Health check

GET /health

Response:

{ "service": "user-service", "status": "UP" }

Create a user

POST /users
Content-Type: application/json

{
  "name": "Mona",
  "email": "mona@example.com"
}

Response 201:

{
  "_id": "64f1a2b3c4d5e6f7a8b9c0d1",
  "name": "Mona",
  "email": "mona@example.com"
}

Get a user by ID

GET /users/:id

---

Order Service — http://localhost:3002

Health check

GET /health

Create an order

POST /orders
Content-Type: application/json

{
  "userId": "<USER_ID>",
  "items": [
    { "productId": "P-100", "quantity": 2 }
  ],
  "totalAmount": 120
}

Response 201:

{
  "_id": "64f1a2b3c4d5e6f7a8b9c0d2",
  "userId": "64f1a2b3c4d5e6f7a8b9c0d1",
  "items": [{ "productId": "P-100", "quantity": 2 }],
  "totalAmount": 120,
  "status": "CREATED"
}

After creating an order, an order.created event is automatically published to RabbitMQ.

Get an order by ID

GET /orders/:id

---

Notification Service — http://localhost:3003

Health check

GET /health

Get all notifications

GET /notifications

Response 200:

[
  {
    "_id": "64f1a2b3c4d5e6f7a8b9c0d3",
    "type": "ORDER_CREATED",
    "recipient": "64f1a2b3c4d5e6f7a8b9c0d1",
    "message": "Order 64f1a2b3c4d5e6f7a8b9c0d2 created successfully. Total amount: 120",
    "status": "SENT"
  }
]

---

RabbitMQ Management UI

Open http://localhost:15672 in your browser.

• Username: guest
• Password: guest

Check the order-events queue to monitor published messages.

---

End-to-End Test (PowerShell)

# 1. Create a user
$user = Invoke-RestMethod -Method Post -Uri "http://localhost:3001/users" `
  -ContentType "application/json" `
  -Body '{"name":"Test User","email":"test@example.com"}'

# 2. Create an order using the returned user ID
$orderBody = @{
  userId = $user._id
  items = @(@{ productId = "P-100"; quantity = 2 })
  totalAmount = 120
} | ConvertTo-Json -Depth 4

$order = Invoke-RestMethod -Method Post -Uri "http://localhost:3002/orders" `
  -ContentType "application/json" -Body $orderBody

# 3. Wait for RabbitMQ event to be processed
Start-Sleep -Seconds 2

# 4. Verify notification was created
$notifications = Invoke-RestMethod http://localhost:3003/notifications
"USER_ID   = $($user._id)"
"ORDER_ID  = $($order._id)"
"NOTIFICATIONS = $($notifications.Count)"
"TYPE      = $($notifications[0].type)"

Expected output:

USER_ID   = <mongo id>
ORDER_ID  = <mongo id>
NOTIFICATIONS = 1
TYPE      = ORDER_CREATED