System Architecture

Deep dive into MegaVault's architecture, design patterns, and technical decisions.

Architecture Overview
System Design
Web Application Architecture
Mobile Application Architecture
Data Flow & Communication
Security Architecture
Scalability Considerations

Architecture Overview

MegaVault follows a modern, microservices-inspired architecture with a Next.js-based full-stack web application and a Flutter-based mobile app. The system is designed for simplicity, maintainability, and scalability while providing a seamless user experience across platforms.

High-Level Architecture

Web Client

→

Next.js API

→

Storage

Mobile App

→

Mobile API

→

Redis

Key Architectural Principles

Separation of Concerns: Clear boundaries between presentation, business logic, and data layers
API-First Design: RESTful APIs that serve both web and mobile clients
Stateless Architecture: Scalable design with minimal server-side state
Security by Default: Built-in authentication, authorization, and data protection
Cloud-Native: Designed for cloud deployment with external storage and databases

System Design

MegaVault uses a monolithic backend with a clean separation between web and mobile API endpoints. This approach provides simplicity for deployment and maintenance while maintaining clear boundaries.

Technology Stack

Frontend

React 18 - UI framework
Next.js 14 - Full-stack framework
TypeScript - Type safety
Tailwind CSS - Styling
Framer Motion - Animations
Three.js - 3D visualization

Backend

Next.js API Routes - Server logic
NextAuth.js - Web authentication
JWT - Mobile authentication
Upstash Redis - Data storage
AWS SDK - S3 integration

Mobile

Flutter - Mobile framework
Dart - Programming language
HTTP Client - API communication
Secure Storage - Token storage
Background Tasks - File uploads

Design Patterns

MVC (Model-View-Controller): Clear separation of concerns in Next.js structure
Repository Pattern: Data access abstraction in service layers
Provider Pattern: State management for session and user data
Factory Pattern: Service instantiation and configuration
Observer Pattern: Event-driven updates in mobile app

Web Application Architecture

The web application follows Next.js App Router conventions with server-side rendering, API routes, and client-side state management.

Directory Structure

src/
├── app/                    # Next.js App Router
│   ├── api/               # API route handlers
│   │   ├── auth/          # Authentication endpoints
│   │   ├── files/         # File management APIs
│   │   ├── mobile/        # Mobile-specific APIs
│   │   └── users/         # User management APIs
│   ├── components/        # React components
│   ├── dashboard/         # Dashboard pages
│   └── globals.css        # Global styles
├── components/            # Shared components
├── lib/                   # Utility libraries
│   ├── auth.ts           # Authentication configuration
│   ├── storage.ts        # Storage service
│   └── config.ts         # Application configuration
├── types/                 # TypeScript definitions
└── middleware.ts          # Next.js middleware

Request Flow

Web Request Processing

Browser sends request to Next.js application

Middleware checks authentication and authorization

API route handler processes the request

Service layer interacts with Redis/Storage

Response returned to client

State Management

Session Provider Example

'use client';

import { SessionProvider as NextAuthSessionProvider } from 'next-auth/react';
import { ReactNode } from 'react';

interface Props {
  children: ReactNode;
  session: any;
}

export function SessionProvider({ children, session }: Props) {
  return (
    <NextAuthSessionProvider session={session}>
      {children}
    </NextAuthSessionProvider>
  );
}

Component Architecture

Page Components: Top-level route components
Layout Components: Shared layouts for different sections
Feature Components: Specific functionality (file upload, preview)
UI Components: Reusable interface elements
Provider Components: Context and state management

Mobile Application Architecture

The Flutter mobile app follows clean architecture principles with clear separation between presentation, domain, and data layers.

Flutter Project Structure

megavault_mobile/
├── lib/
│   ├── screens/           # UI screens
│   │   ├── login_screen.dart
│   │   ├── home_screen.dart
│   │   └── file_preview_screen.dart
│   ├── services/          # Business logic
│   │   ├── auth_service.dart
│   │   ├── file_service.dart
│   │   └── background_upload_service.dart
│   ├── utils/             # Utilities
│   │   ├── api_config.dart
│   │   ├── file_utils.dart
│   │   └── url_helper.dart
│   ├── widgets/           # Reusable widgets
│   └── main.dart          # App entry point
├── android/               # Android-specific code
├── ios/                   # iOS-specific code
└── pubspec.yaml          # Dependencies

Architecture Layers

Presentation Layer

UI screens, widgets, and user interaction handling

• Screens (login, home, file preview)
• Widgets (file list, upload progress)
• State management (provider/bloc)

Domain Layer

Business logic and use cases

• Authentication logic
• File operations
• Background upload management

Data Layer

API communication and local storage

• HTTP API client
• Local secure storage
• Cache management

Service Architecture

Service Pattern Example

class FileService {
  final ApiClient _apiClient;
  final CacheService _cacheService;

  FileService(this._apiClient, this._cacheService);

  Future<List<FileItem>> getFiles(String path) async {
    try {
      // Try cache first
      final cachedFiles = await _cacheService.getFiles(path);
      if (cachedFiles != null) {
        return cachedFiles;
      }

      // Fetch from API
      final response = await _apiClient.get('/api/mobile/files/list?folder=$path');
      final files = FileItem.fromJsonList(response.data['files']);
      
      // Cache the result
      await _cacheService.setFiles(path, files);
      
      return files;
    } catch (e) {
      throw FileServiceException('Failed to fetch files: $e');
    }
  }
}

Data Flow & Communication

MegaVault implements a clear data flow pattern with RESTful APIs serving both web and mobile clients.

API Communication

File Upload Flow

Client selects file and initiates upload

Authentication middleware validates user session/token

Upload API processes file and validates constraints

File uploaded to S3-compatible storage

Metadata stored in Redis database

Success response returned to client

Storage Architecture

Redis: User data, sessions, file metadata, and caching
S3 Storage: Binary file storage with signed URL access
Local Cache: Mobile app caches metadata and thumbnails
Session Storage: Web browser stores temporary UI state

Real-time Updates

While MegaVault doesn't currently implement WebSocket connections, it uses polling and event-driven updates for real-time functionality:

Polling Pattern

// File list auto-refresh
useEffect(() => {
  const interval = setInterval(async () => {
    try {
      const updatedFiles = await fetchFiles();
      setFiles(updatedFiles);
    } catch (error) {
      console.error('Failed to refresh files:', error);
    }
  }, 30000); // Refresh every 30 seconds

  return () => clearInterval(interval);
}, []);

Security Architecture

Security is built into every layer of MegaVault, from authentication to data storage and transmission.

Authentication & Authorization

Web Sessions: HTTP-only cookies with CSRF protection
Mobile Tokens: JWT tokens with secure storage
API Security: All endpoints require authentication
Role-based Access: User isolation through folder-based permissions

Data Protection

Encrypted Transmission: HTTPS/TLS for all communications
Signed URLs: Time-limited access to storage objects
Input Validation: Comprehensive validation and sanitization
Error Handling: Secure error messages without information leakage

Security Middleware

Authentication Middleware

import { NextRequest, NextResponse } from 'next/server';
import { getToken } from 'next-auth/jwt';

export async function middleware(request: NextRequest) {
  const { pathname } = request.nextUrl;

  // Public paths that don't require authentication
  if (pathname.startsWith('/api/health') || 
      pathname.startsWith('/api/files/public')) {
    return NextResponse.next();
  }

  // Check for session or JWT token
  const token = await getToken({ req: request });
  const authHeader = request.headers.get('authorization');

  if (!token && !authHeader) {
    return new NextResponse('Unauthorized', { status: 401 });
  }

  return NextResponse.next();
}

⚠️

Security Best Practices

Always use HTTPS in production environments
Regularly rotate JWT secrets and API keys
Implement rate limiting for API endpoints
Monitor for suspicious activity and failed login attempts
Keep dependencies updated for security patches

Scalability Considerations

MegaVault is designed to scale from single-user deployments to multi-tenant installations with thousands of users.

Horizontal Scaling

Stateless Design: API servers can be scaled horizontally
External Storage: S3-compatible storage scales independently
Redis Clustering: Redis can be clustered for high availability
Load Balancing: Multiple API instances behind a load balancer

Performance Optimization

CDN Integration: Static assets served via CDN
Caching Strategy: Multi-layer caching (browser, Redis, CDN)
Image Optimization: Automatic image compression and resizing
Lazy Loading: Progressive loading of file lists and previews

Monitoring & Observability

Health Check Endpoint

// app/api/health/route.ts
export async function GET() {
  try {
    // Check Redis connectivity
    const redisCheck = await redis.ping();
    
    // Check storage connectivity
    const storageCheck = await s3Client.send(new ListBucketsCommand({}));
    
    return Response.json({
      status: 'healthy',
      timestamp: new Date().toISOString(),
      services: {
        redis: redisCheck === 'PONG' ? 'healthy' : 'unhealthy',
        storage: storageCheck ? 'healthy' : 'unhealthy'
      }
    });
  } catch (error) {
    return Response.json(
      { status: 'unhealthy', error: error.message },
      { status: 500 }
    );
  }
}

Future Enhancements

Microservices Migration: Split into dedicated services as needed
Event-Driven Architecture: Implement message queues for async processing
Multi-Region Deployment: Geo-distributed storage and compute
Advanced Analytics: Usage metrics and performance monitoring

Understanding the Architecture

This architecture provides a solid foundation for cloud storage while maintaining simplicity and developer productivity.

Development Setup →Deployment Guide →