Caching Demo

This repository demonstrates basic HTTP caching techniques in a Node.js Express server, including the use of Cache-Control headers and ETag for efficient API responses.

Features

• Express.js API: Serves a simple /api/users endpoint with dummy user data.
• Cache-Control Header: Instructs browsers and proxies to cache API responses for 20 seconds.
• ETag Support: Uses an MD5 hash of the response data to provide ETag headers, allowing clients to avoid downloading unchanged data.
• 304 Not Modified: If the client sends a matching ETag, the server responds with a 304 status, saving bandwidth.
• Frontend Demo: index.html provides a button to fetch users and display the response status, headers, and data.

How It Works

1. Server Setup: The Express server runs on port 3000 and serves both the API and the frontend HTML.
2. API Caching:
   • Every /api/users response includes a Cache-Control: public, max-age=20 header (cache for 20 seconds).
   • The server generates an ETag for the user data. If the client sends an If-None-Match header with a matching ETag, the server returns 304 Not Modified.
3. Frontend:
   • Open http://localhost:3000 in your browser.
   • Click "Fetch Users" to make an API request and see caching in action.

Files

• server.js: Express server with API and caching logic.
• index.html: Simple frontend to test the API and caching.
• package.json: Project metadata and dependencies.

Getting Started

1. Install dependencies:

   npm install

2. Start the server:

   node server.js

3. Open your browser at http://localhost:3000