MERN Marketplace Microservices

A modular marketplace backend built as a set of Node.js microservices. The architecture uses separate services for authentication, products, cart, orders, payments, notifications, seller operations, and an AI shopping assistant.

Overview

• Backend stack: Node.js, Express, MongoDB, RabbitMQ, Redis, JWT, Razorpay.
• Frontend: React + Vite + Redux Toolkit Query (external client assumed).
• Deployment target: Docker / AWS ECR → ECS Fargate behind an ALB with path-based routing.
• Observability: request logging, request correlation IDs, structured logs.
• Security: JWT auth, refresh tokens, CORS, CSRF protections, input validation, RBAC.

Architecture

This repo is organized as one folder per microservice:

• auth/ — authentication, user management, token issuance.
• product/ — catalog CRUD, seller product management.
• cart/ — shopping cart operations.
• order/ — order creation, status changes, order history.
• payment/ — Razorpay payment orchestration and verification.
• notification/ — email notifications and event listeners.
• ai-buddy/ — AI shopping assistant and natural language query support.
• seller-dashboard/ — seller analytics, order view, inventory management.

Each service is implemented as a standalone Express application and can be run independently.

Service Ports

Service	Folder	Default Port
Auth	auth/	3000
Product	product/	3001
Cart	cart/	3002
Order	order/	3003
Payment	payment/	3004
AI Buddy	ai-buddy/	3005
Notification	notification/	3006
Seller Dashboard	seller-dashboard/	3007

Core Service Responsibilities

Auth Service (auth/)

Handles:

• user registration and login
• JWT access / refresh token management
• user profile and address management
• secure session handling

Product Service (product/)

Handles:

• product listing, search, filtering, pagination
• product detail retrieval and image handling
• seller product creation, updates, deletion
• event publishing for product lifecycle changes

Cart Service (cart/)

Handles:

• add / update / remove cart items
• cart retrieval and total calculation
• price revalidation to prevent client-side tampering

Order Service (order/)

Handles:

• converting cart contents into orders
• order lifecycle state management
• shipping address updates before payment
• order cancellation flow

Payment Service (payment/)

Handles:

• Razorpay order creation and verification
• payment record storage
• secure gateway integration

Notification Service (notification/)

Handles:

• email notification delivery
• asynchronous event consumption from RabbitMQ
• decoupled notification workflow

AI Buddy Service (ai-buddy/)

Handles:

• natural language product search
• conversational shopping assistance
• cart creation and intent-driven actions

Seller Dashboard (seller-dashboard/)

Handles:

• seller analytics and revenue metrics
• order list for sellers
• inventory management and product status

Data Flow

• Services communicate using REST APIs and event-driven messaging.
• RabbitMQ is used for asynchronous events such as user creation, product updates, order creation, and notifications.
• MongoDB stores domain data for each service.
• Redis is available for caching, rate limiting, and session protection when configured.

Local Setup

1. Install Node.js 18+.
2. Install dependencies in each service folder:

   cd auth && npm install
   cd ../product && npm install
   cd ../cart && npm install
   cd ../order && npm install
   cd ../payment && npm install
   cd ../notification && npm install
   cd ../ai-buddy && npm install
   cd ../seller-dashboard && npm install

3. Provision infrastructure:
   • MongoDB or MongoDB Atlas
   • RabbitMQ
   • Redis (optional)
4. Configure environment variables for each service. Common values include:
   • MONGO_URI
   • JWT_SECRET
   • JWT_REFRESH_SECRET
   • RABBITMQ_URL
   • PORT
   • RAZORPAY_KEY_ID
   • RAZORPAY_KEY_SECRET
   • EMAIL_HOST, EMAIL_PORT, EMAIL_USER, EMAIL_PASS
5. Start services:

   cd auth && node server.js
   cd ../product && node server.js
   cd ../cart && node server.js
   cd ../order && node server.js
   cd ../payment && node server.js
   cd ../notification && node server.js
   cd ../seller-dashboard && node server.js
   cd ../ai-buddy && node server.js

Use multiple terminals or a process manager like pm2 to run services in parallel.

Testing

Each service supports tests from its own folder.

cd auth && npm test

Repeat for product, cart, order, payment, and other services with tests.

Deployment Notes

• Services are designed for separate containers.
• AWS ECS Fargate is a good deployment target.
• Use an ALB with path-based routing to forward traffic to each service.
• Store secrets securely and avoid hardcoding API credentials.

Observability

• Request logging is enabled in the services.
• Correlation IDs can trace requests across services.
• Logs can be forwarded to CloudWatch or another centralized log service.

Security Highlights

• JWT access and refresh tokens for authentication.
• HttpOnly refresh cookies.
• Input validation with express-validator and zod.
• Role-based access control for protected endpoints.
• Rate limiting and CORS protections where configured.

Recommended Improvements

• add .env.example files for every service
• add Dockerfiles and a root docker-compose.yml
• document endpoint contracts for frontend integration
• add API versioning and health checks

Folder Summary

• auth/ — authentication and user management
• product/ — product catalog and seller operations
• cart/ — cart lifecycle management
• order/ — order creation and order history
• payment/ — Razorpay payment flow
• notification/ — email notifications and event listeners
• ai-buddy/ — conversational shopping assistant
• seller-dashboard/ — seller analytics and operations

Stores user notifications (email, SMS, in-app).

{
  "notificationId": "string (UUID)",
  "userId": "string (FK → User.userId)",
  "type": "enum: ['email', 'sms', 'push']",
  "message": "string",
  "status": "enum: ['pending', 'sent', 'failed']",
  "createdAt": "date"
}

---

7. Review Entity

(Optional but common in e-commerce).

{
  "reviewId": "string (UUID)",
  "productId": "string (FK → Product.productId)",
  "userId": "string (FK → User.userId)",
  "rating": "number (1-5)",
  "comment": "string",
  "createdAt": "date"
}

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Final Entity Count

• User
• Product
• Cart
• Order
• Payment
• Notification

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Service–Entity Mapping Table

Service	Entities Owned	Responsibilities	Dependencies	RabbitMQ Events
Auth/User Service	User	Register/login, issue tokens, manage profiles & addresses, emit USER_CREATED/UPDATED	Needed by all services (for auth)	Emits user.created, user.updated
Product Service	Product (and optional Review)	CRUD products, manage stock, serve product data to Cart/Order, emit PRODUCT_CREATED/UPDATED/DELETED	Cart, Order, Review Service	Emits product.created, product.updated
Cart Service	Cart	Add/remove items, validate stock/price, compute totals, maintain one cart per user	Product Service (for price/stock)	Subscribes to product.updated (optional)

| | Order Service | Order | Create/manage orders, track lifecycle, reserve inventory, emit ORDER_CREATED/UPDATED | Cart, Payment, Notification | Emits order.created, order.cancelled | | Payment Service | Payment | Handle Razorpay/Stripe integration, verify payments, emit PAYMENT_SUCCESS/FAILED | Order, Notification | Emits payment.success, payment.failed | | Notification Service | Notification | Listen to events, send emails/SMS/push, track delivery status | User, Order, Payment | Subscribes to all major events (order.created, payment.success, etc.) | | Seller Dashboard Service | Aggregated seller metrics & insights | /seller/dashboard/metrics, /seller/dashboard/orders, /seller/dashboard/products | | Subscribes to order.created, payment.success, product.updated |

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