📘 CHRONICA: Scalable Full-Stack Web & Mobile Application - Monorepo Architecture

Suggested By: Juned Ahmad Ansari

📌 Table of Contents

1. Introduction
2. Technology Stack
3. Monorepo Setup (Lerna + Workspaces)
4. Frontend (Next.js Web + React Native Mobile)
5. Backend (Express.js + MongoDB + GraphQL/gRPC)
6. State Management (React Query, Redux Toolkit)
7. Authentication & Security Best Practices
8. Testing Strategy (Unit, Integration, E2E, Load Testing)
9. Debugging & Performance Optimization
10. CI/CD & Deployment Strategy
11. Logging & Monitoring
12. Scaling & Future Enhancements

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1️⃣ Introduction

This scalable full-stack architecture is designed for web and mobile applications using a monorepo approach with Lerna. It ensures: ✅ Modular architecture for reusability and maintainability
✅ Efficient CI/CD pipeline for fast deployment
✅ Security best practices for a robust application
✅ Performance optimization using caching and auto-scaling

A monorepo approach allows us to manage both the web and mobile applications under a single repository, making it easier to share code, enforce consistency, and improve developer efficiency. This approach is particularly beneficial for large-scale applications where multiple teams are working on different parts of the project.

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2️⃣ Technology Stack

Layer	Technology	Why?
Frontend (Web)	Next.js 14 (SSR, SSG, Edge Functions)	Provides fast performance, SEO benefits, and hybrid static & server rendering.
Frontend (Mobile)	React Native (Expo, Hermes)	Enables cross-platform mobile development with near-native performance.
Backend	Express.js + Node.js	Lightweight, fast, and scalable backend framework for building REST and GraphQL APIs.
Database	MongoDB (Mongoose / Prisma)	NoSQL database with great scalability and flexibility for handling unstructured data.
API Communication	GraphQL (Apollo) / REST / gRPC	GraphQL for efficient querying, REST for compatibility, and gRPC for high-performance microservices.
State Management	React Query, Redux Toolkit	React Query for data fetching and caching, Redux for global state management.
Authentication	NextAuth.js, JWT, OAuth 2.0	Secure authentication solutions for different use cases, including social login.
Testing	Jest, Cypress, Detox, Supertest	Covers unit, integration, and end-to-end testing for reliability.
CI/CD	GitHub Actions, Docker, Kubernetes	Automates deployment, improves reliability, and enables auto-scaling.
Caching	Redis, CDN (Cloudflare, AWS CloudFront)	Improves performance and reduces database load by caching frequent requests.
Logging & Monitoring	Winston, Prometheus, Grafana, Sentry	Provides real-time tracking of logs, errors, and system health.

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3️⃣ Monorepo Setup (Lerna + Yarn Workspaces)

Using Lerna with Yarn Workspaces allows efficient dependency management and better modularization.

npm install -g lerna
npx lerna init

Modify lerna.json:

{
  "packages": ["packages/*"],
  "npmClient": "yarn",
  "useWorkspaces": true,
  "version": "0.1.0"
}

Run:

npx lerna bootstrap

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4️⃣ Frontend (Next.js Web + React Native Mobile)

Web App (Next.js 14)

Next.js is chosen for its SEO benefits, fast performance, and ability to support both server-side rendering (SSR) and static site generation (SSG).

npx create-next-app packages/web
cd packages/web
npm install axios react-query next-auth mongoose

API Calls (lib/api.js):

import axios from 'axios';
const API_URL = process.env.NEXT_PUBLIC_API_URL;
export const loginUser = async (email, password) => axios.post(`${API_URL}/auth/login`, { email, password });

Mobile App (React Native Expo)

React Native allows cross-platform mobile development with near-native performance. Expo simplifies the development process by providing a managed workflow.

npx create-expo-app packages/mobile
cd packages/mobile
npm install axios react-navigation react-query @react-navigation/native

Navigation (navigation.js):

import { createStackNavigator } from '@react-navigation/stack';
const Stack = createStackNavigator();
export default function Navigation() {
  return (
    <NavigationContainer>
      <Stack.Navigator>
        <Stack.Screen name="Login" component={LoginScreen} />
      </Stack.Navigator>
    </NavigationContainer>
  );
}

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5️⃣ Backend (Express.js + MongoDB + GraphQL/gRPC)

mkdir -p packages/backend && cd packages/backend
npm init -y
npm install express mongoose cors dotenv jsonwebtoken bcryptjs graphql apollo-server-express

Why Express.js?

• Lightweight & Fast: Ideal for building APIs with minimal overhead.
• Middleware Support: Enables flexible request handling.
• Ecosystem: Works well with WebSockets, GraphQL, and other modern technologies.

User Authentication (controllers/authController.js):

const bcrypt = require('bcryptjs');
const jwt = require('jsonwebtoken');
const User = require('../models/User');
exports.loginUser = async (req, res) => {
  const { email, password } = req.body;
  const user = await User.findOne({ email });
  if (!user || !(await bcrypt.compare(password, user.password))) return res.status(400).json({ message: "Invalid credentials" });
  const token = jwt.sign({ userId: user._id }, process.env.JWT_SECRET, { expiresIn: '1h' });
  res.json({ token });
};

6️⃣ State Management (React Query, Redux Toolkit)

State management is critical for handling shared application state efficiently.

Why React Query?

• Handles server-state efficiently.
• Built-in caching and automatic background fetching.
• Reduces API calls by managing stale data.

npm install @tanstack/react-query

Example (hooks/useUser.js):

import { useQuery } from '@tanstack/react-query';
const fetchUser = async () => (await fetch('/api/user')).json();
export const useUser = () => useQuery(['user'], fetchUser);

Why Redux Toolkit?

• Centralized global state management.
• Works well with asynchronous data fetching.

npm install @reduxjs/toolkit react-redux

Redux Store (store.js):

import { configureStore } from '@reduxjs/toolkit';
export const store = configureStore({ reducer: { user: userReducer } });

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7️⃣ Authentication & Security Best Practices

Security is crucial in any full-stack application.

Authentication

• NextAuth.js: Ideal for web authentication with OAuth, JWT, and email/password.
• JWT (JSON Web Token): Used for stateless authentication in mobile apps.

npm install next-auth jsonwebtoken bcryptjs

Example NextAuth.js Config (api/auth/[...nextauth].js):

import NextAuth from 'next-auth';
import Providers from 'next-auth/providers';
export default NextAuth({ providers: [Providers.Credentials({...})] });

Security Best Practices

✅ Password Hashing using bcryptjs. ✅ Rate Limiting to prevent brute force attacks (express-rate-limit). ✅ CORS Handling for secure API requests.

npm install express-rate-limit helmet

Example (server.js):

const rateLimit = require('express-rate-limit');
app.use(rateLimit({ windowMs: 15 * 60 * 1000, max: 100 }));
app.use(require('helmet')());

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8️⃣ Testing Strategy (Unit, Integration, E2E, Load Testing)

Comprehensive testing ensures stability and reliability.

Test Type	Tool	Purpose
Unit Testing	Jest	Test individual functions/components.
Integration Testing	Supertest	Validate API behavior.
E2E Testing (Web)	Cypress	Test full UI workflows.
E2E Testing (Mobile)	Detox	Automated mobile UI tests.
Load Testing	k6	Measure performance under stress.

npm install --save-dev jest supertest cypress detox k6

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9️⃣ Debugging & Performance Optimization

Debugging

• VS Code Debugger: Set breakpoints & step through code.
• Chrome DevTools: Inspect network & console logs.

VS Code Debugger Config (launch.json):

{
  "version": "0.2.0",
  "configurations": [{ "name": "Debug Backend", "type": "node", "request": "launch", "program": "${workspaceFolder}/packages/backend/index.js" }]
}

Performance Optimization

✅ Use Redis for caching API responses. ✅ Optimize database queries with indexing. ✅ Lazy load React components to reduce initial page load time.

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🔟 CI/CD & Deployment Strategy

Automating deployment with GitHub Actions, Docker, and Kubernetes.

name: Deploy Backend
on: push
jobs:
  deploy:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v3
      - name: Install Dependencies
        run: cd packages/backend && npm install
      - name: Deploy
        run: pm2 restart backend

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1️⃣1️⃣ Logging & Monitoring

✅ Winston + Morgan for API Logging ✅ Prometheus + Grafana for Monitoring ✅ Sentry for Error Tracking

npm install winston morgan sentry

Example (logger.js):

const winston = require('winston');
const logger = winston.createLogger({ transports: [new winston.transports.Console()] });
module.exports = logger;

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1️⃣2️⃣ Scaling & Future Enhancements

To ensure future growth, we follow scalable patterns: ✅ Microservices Architecture – Break large features into independent services. ✅ Serverless Functions – Reduce infrastructure costs for event-driven operations. ✅ Auto-scaling with Kubernetes – Handle high traffic efficiently. ✅ GraphQL Federation – Optimized data fetching across microservices.

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🚀 Final Thoughts

This scalable architecture ensures: ✅ Microservices for modularity
✅ Kubernetes for auto-scaling
✅ GraphQL for optimized API calls
✅ Security best practices applied