API Monitoring and Analytics: Building Observability

// Express.js monitoring middleware
const monitoring = require('./monitoring');

app.use((req, res, next) => {
  const start = Date.now();
  
  res.on('finish', () => {
    const duration = Date.now() - start;
    monitoring.recordMetric({
      endpoint: req.path,
      method: req.method,
      statusCode: res.statusCode,
      duration: duration,
      timestamp: new Date()
    });
  });
  
  next();
});