// Express — Cache-Control for API responses
app.get('/api/posts/:postId', async (req, res) => {
  const post = await getPost(req.params.postId);

  // Public post — cache for 5 minutes at CDN
  res.set('Cache-Control', 'public, max-age=300, s-maxage=300');
  res.json(post);
});

app.get('/api/trending', async (req, res) => {
  const trending = await getTrending();

  // Trending changes slowly — cache for 1 minute
  res.set('Cache-Control', 'public, max-age=60, stale-while-revalidate=300');
  res.json(trending);
});

app.get('/api/user/me', async (req, res) => {
  const user = await getAuthenticatedUser(req);

  // User-specific — never cache at CDN
  res.set('Cache-Control', 'private, no-store');
  res.json(user);
});

CDN — Content Delivery Networks

CDN — Content Delivery Networks

CDN — Content Delivery Networks