🏗️ System Architecture

SourceNet follows a microservices-oriented architecture that combines frontend, backend, blockchain, and decentralized storage layers.

Architecture Overview

┌─────────────┐         ┌──────────────┐         ┌───────────────┐
│   Frontend  │────────▶│    Backend   │────────▶│  SUI Blockchain│
│  (Next.js)  │         │  (Express)   │         │   (Move SC)    │
└─────────────┘         └──────────────┘         └───────────────┘
                              │    │
                              │    │
                         ┌────▼────▼────┐
                         │  PostgreSQL   │
                         │    + Redis    │
                         └───────────────┘
                              │
                         ┌────▼────┐
                         │ Walrus  │
                         │ Storage │
                         └─────────┘

Key Components

1. Frontend Layer (Next.js)

The user-facing application built with Next.js 14, featuring server-side rendering, client components for interactivity, and state management with Zustand.

• Pages: Marketplace, Seller Dashboard, Buyer Dashboard, Authentication
• Components: Reusable UI components with Tailwind CSS
• Hooks: Custom hooks for zkLogin, API calls, and blockchain interactions
• State Management: Zustand for global state (user, auth, purchases)

2. Backend API (Express.js)

RESTful API server handling authentication, data processing, and blockchain integration.

• Controllers: Auth, Seller, Buyer, Review, AI
• Services: Blockchain, Storage, Encryption, Cache, AI
• Middleware: JWT authentication, rate limiting, validation
• Job Queue: BullMQ for background processing (data encryption, fulfillment)

3. Database Layer (PostgreSQL)

Relational database for storing user data, DataPod metadata, purchases, and reviews.

4. Cache Layer (Redis)

In-memory cache for session management, rate limiting, and temporary data storage.

• Sessions: JWT tokens and user sessions
• Rate Limiting: API request throttling per user/IP
• Caching: Frequently accessed DataPod metadata
• Download Tokens: Temporary signed URLs for data downloads

5. Blockchain Layer (SUI)

Smart contracts written in Move language handle on-chain logic and asset management.

• DataPod Module: Create and manage DataPod objects
• Purchase Module: Handle purchase requests and payments
• Escrow Module: Lock and release funds securely
• Events: Emit events for indexer synchronization

6. Storage Layer (Walrus Protocol)

Decentralized storage for encrypted data files using erasure coding and distributed nodes.

• Publisher: Upload encrypted data and receive blob IDs
• Gateway: Retrieve data from distributed storage nodes
• Erasure Coding: Split data into redundant chunks
• High Availability: Data accessible even if some nodes fail

7. Real-time Layer (WebSocket)

WebSocket server for live updates and notifications.

• Purchase Notifications: Alert buyers when purchases complete
• Marketplace Updates: Real-time DataPod listings
• Seller Alerts: Notify sellers of new purchases

8. Indexer Service

Background service that synchronizes blockchain events with the database.

• Event Polling: Query SUI blockchain every 5 seconds
• Event Processing: Parse and store on-chain events
• Checkpoint Tracking: Track last processed block
• Database Sync: Update local database with blockchain state

Data Flow Diagram

User Browser
    │
    │ (1) HTTP/HTTPS
    ▼
Next.js Frontend
    │
    │ (2) REST API + WebSocket
    ▼
Express.js Backend
    │
    ├─── (3) SQL ────▶ PostgreSQL
    │
    ├─── (4) Cache ──▶ Redis
    │
    ├─── (5) Upload ─▶ Walrus Storage
    │
    └─── (6) TX ─────▶ SUI Blockchain
                          │
                          │ (7) Events
                          ▼
                      Indexer Service
                          │
                          └──▶ PostgreSQL

Security Architecture

Authentication Security

• zkLogin: Zero-knowledge proofs for privacy-preserving authentication
• JWT Tokens: Signed tokens with 7-day expiration
• Salt Storage: Unique salts per user stored securely

Data Security

• AES-256 Encryption: All data encrypted at rest
• Per-Purchase Encryption: Unique encrypted copy per buyer
• Key Management: Encryption keys stored separately from data

Network Security

• HTTPS Only: All communication encrypted in transit
• Rate Limiting: 20 requests/min per user, 100/min per IP
• Input Validation: Zod schemas for all API inputs

Scalability Considerations