Exhibition Backend

Off-chain metadata service for the Exhibition protocol.

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Overview

Exhibition is a fully on-chain protocol — all launch parameters, contributions, liquidity events, and fund flows are enforced and recorded on Nexus Layer 1. This backend does not touch any of that.

Its sole responsibility is storing and serving the off-chain metadata that projects optionally attach to their launches: a human-readable overview and social links. This data is purely presentational — it has no effect on protocol execution and is never referenced by the smart contracts.

Access is authenticated via wallet signature and JWT, ensuring only a verified project owner can update their own launch metadata.

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Responsibilities

• Authenticate project owners via wallet signature and issue a JWT
• Store and update off-chain launch metadata — overview text and social links — per project
• Serve metadata to the frontend by project ID

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Tech Stack

Layer	Technology
Runtime	Node.js 18+
Framework	Express
Database	MongoDB Atlas
Auth	Wallet signature + JWT
Sessions	Cookies

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Authentication Flow

1. Frontend requests a challenge nonce for a given wallet address
2. User signs the nonce with their wallet (EIP-191)
3. Backend verifies the signature and confirms wallet ownership
4. Backend issues a signed JWT stored in an HTTP-only cookie
5. Subsequent requests to protected routes are authenticated via the cookie

This ensures only the verified owner of a wallet address can create or update metadata for launches associated with that address.

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API Reference

Auth

POST /auth/challenge Request a sign message challenge for a wallet address.

// Request
{ "address": "0x123..." }

// Response
{ "nonce": "Sign this message to verify your wallet: a3f9..." }

POST /auth/verify Verify a signed challenge and issue a JWT cookie.

// Request
{ "address": "0x123...", "signature": "0xabc..." }

// Response
{ "success": true }
// Sets HTTP-only JWT cookie

POST /auth/logout Clear the JWT cookie and end the session.

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Metadata

GET /projects/:projectId/metadata Fetch off-chain metadata for a project. Public — no authentication required.

// Response
{
  "projectId": "42",
  "overview": "A short description of the project...",
  "socials": {
    "website": "https://example.xyz",
    "twitter": "https://twitter.com/example",
    "telegram": "https://t.me/example",
    "discord": "https://discord.gg/example",
    "github": "https://github.com/example"
  }
}

POST /projects/:projectId/metadata Create or update metadata for a project. Requires a valid JWT cookie. The authenticated wallet must match the project owner address on-chain.

// Request
{
  "overview": "A short description of the project...",
  "socials": {
    "website": "https://example.xyz",
    "twitter": "https://twitter.com/example",
    "telegram": "https://t.me/example",
    "discord": "https://discord.gg/example",
    "github": "https://github.com/example"
  }
}

// Response
{ "success": true }

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Data Model

// ProjectMetadata
{
  projectId:  String,   // On-chain project ID (unique)
  address:    String,   // Owner wallet address
  overview:   String,   // Project description (plaintext)
  socials: {
    website:  String,
    twitter:  String,
    telegram: String,
    discord:  String,
    github:   String,
  },
  updatedAt:  Date,
}

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Getting Started

Prerequisites

• Node.js 18+
• A MongoDB Atlas cluster and connection string

Installation

git clone https://github.com/ExhibitionDefi/exhibition-backend
cd exhibition-backend
npm install

Environment Variables

Create a .env file in the root:

# Server
PORT=4000
NODE_ENV=development

# MongoDB
MONGODB_URI=mongodb+srv://<user>:<password>@cluster.mongodb.net/exhibition

# JWT
JWT_SECRET=your_jwt_secret_here
JWT_EXPIRES_IN=7d

# Cookie
COOKIE_SECRET=your_cookie_secret_here

# CORS
ALLOWED_ORIGIN=http://localhost:3000

Development

npm run dev

Server runs at http://localhost:4000.

Build & Start

npm run build
npm start

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Project Structure

src/
├── routes/
│   ├── auth.ts          # Wallet signature + JWT endpoints
│   └── metadata.ts      # Project metadata endpoints
├── controllers/
│   ├── auth.ts          # Auth logic
│   └── metadata.ts      # Metadata CRUD logic
├── middleware/
│   ├── authenticate.ts  # JWT cookie verification
│   └── validate.ts      # Request body validation
├── models/
│   └── ProjectMetadata.ts  # Mongoose schema
├── lib/
│   ├── db.ts            # MongoDB Atlas connection
│   ├── jwt.ts           # JWT sign + verify helpers
│   └── signature.ts     # EIP-191 signature verification
└── app.ts               # Express app entry point

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Security Notes

• JWTs are stored in HTTP-only cookies — not accessible to client-side JavaScript
• Signature verification confirms wallet ownership before any write is permitted
• All write operations validate that the authenticated wallet matches the project owner address recorded on-chain
• No private keys or on-chain state are ever handled by this service

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License

MIT

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Built by the Exhibition Developer

App • GitHub • Twitter