/**
* BEFORE MIGRATION: x402-only API
*
* This example shows a typical x402 payment-gated API before
* migrating to the AI Service Marketplace.
*
* Run: pnpm demo:before
*/
import express, { Request, Response, NextFunction } from "express";
const app = express();
app.use(express.json());
// ============================================================================
// Configuration (x402 only)
// ============================================================================
const config = {
port: 3001,
walletAddress: "0x40252CFDF8B20Ed757D61ff157719F33Ec332402" as `0x${string}`,
pricing: {
"GET /api/weather": "$0.001",
"GET /api/forecast": "$0.005",
"GET /api/alerts": "$0.002",
},
};
// ============================================================================
// Simple x402 Payment Middleware (Simplified for demo)
// ============================================================================
interface PaymentInfo {
amount: string;
txHash: string;
payer: string;
}
function parsePaymentHeader(header: string | undefined): PaymentInfo | null {
if (!header) return null;
try {
return JSON.parse(Buffer.from(header, "base64").toString());
} catch {
return null;
}
}
function x402Middleware(pricing: Record<string, string>) {
return (req: Request, res: Response, next: NextFunction) => {
const routeKey = `${req.method} ${req.path}`;
const price = pricing[routeKey];
// Skip if route is not priced
if (!price) {
return next();
}
// Check for payment
const paymentHeader = req.header("X-Payment");
const payment = parsePaymentHeader(paymentHeader);
if (!payment) {
// Return 402 Payment Required
res.status(402).json({
error: "Payment Required",
price,
payTo: config.walletAddress,
acceptedTokens: ["USDC"],
network: "arbitrum",
});
return;
}
// In production: verify payment on-chain
// For demo, we accept any payment header
console.log(`Payment received: ${payment.amount} from ${payment.payer}`);
next();
};
}
// ============================================================================
// Weather API Endpoints
// ============================================================================
// Free health check
app.get("/health", (_req: Request, res: Response) => {
res.json({ status: "ok", version: "1.0.0" });
});
// Apply x402 middleware
app.use(x402Middleware(config.pricing));
// Paid: Get current weather
app.get("/api/weather", (req: Request, res: Response) => {
const city = req.query.city || "San Francisco";
res.json({
city,
temperature: Math.round(15 + Math.random() * 15),
humidity: Math.round(40 + Math.random() * 40),
conditions: ["Sunny", "Cloudy", "Partly Cloudy", "Rainy"][Math.floor(Math.random() * 4)],
windSpeed: Math.round(5 + Math.random() * 20),
timestamp: new Date().toISOString(),
});
});
// Paid: Get 7-day forecast
app.get("/api/forecast", (req: Request, res: Response) => {
const city = req.query.city || "San Francisco";
const days = [];
for (let i = 0; i < 7; i++) {
const date = new Date();
date.setDate(date.getDate() + i);
days.push({
date: date.toISOString().split("T")[0],
high: Math.round(18 + Math.random() * 12),
low: Math.round(8 + Math.random() * 8),
conditions: ["Sunny", "Cloudy", "Partly Cloudy", "Rainy"][Math.floor(Math.random() * 4)],
precipitation: Math.round(Math.random() * 100),
});
}
res.json({
city,
forecast: days,
timestamp: new Date().toISOString(),
});
});
// Paid: Get weather alerts
app.get("/api/alerts", (req: Request, res: Response) => {
const city = req.query.city || "San Francisco";
res.json({
city,
alerts: [
{
type: "HEAT_ADVISORY",
severity: "moderate",
message: "High temperatures expected this afternoon",
expires: new Date(Date.now() + 6 * 60 * 60 * 1000).toISOString(),
},
],
timestamp: new Date().toISOString(),
});
});
// ============================================================================
// Start Server
// ============================================================================
app.listen(config.port, () => {
console.log(`
╔══════════════════════════════════════════════════════════════════╗
║ BEFORE MIGRATION: x402 Only ║
╠══════════════════════════════════════════════════════════════════╣
║ Weather API running at http://localhost:${config.port} ║
║ ║
║ Pricing: ║
║ GET /api/weather - $0.001 per request ║
║ GET /api/forecast - $0.005 per request ║
║ GET /api/alerts - $0.002 per request ║
║ ║
║ Problems with x402 only: ║
║ ❌ No service discovery - AI agents can't find you ║
║ ❌ No subscriptions - users pay per request ║
║ ❌ No analytics - no visibility into usage ║
║ ❌ No reputation - no way to build trust ║
║ ║
║ Test with: ║
║ curl http://localhost:${config.port}/api/weather?city=NYC ║
║ (Will return 402 - Payment Required) ║
╚══════════════════════════════════════════════════════════════════╝
`);
});
export { app };
