Exercise 9 + Instructions

Code-examples/Ex9/Instructions.md

+Here's how you can set up a simple server and then inspect and minimize the HTTP headers manually.
+
+**Backend Setup:**
+
+1. **Install Node.js**: If you haven't already, install Node.js from [nodejs.org](https://nodejs.org/).
+
+2. **Set up your project directory and install Express**:
+
+```bash
+mkdir my_project
+cd my_project
+npm init -y
+npm install express
+```
+
+3. **Create a file named `server.js`** and add the following code to set up an Express server that serves a static file with minimal headers:
+
+```javascript
+const express = require('express');
+const app = express();
+const port = 3000;
+
+app.use((req, res, next) => {
+  // Express adds a header "X-Powered-By: Express" by default, but it's not needed
+  res.removeHeader("X-Powered-By");
+  next();
+});
+
+app.get('/', (req, res) => {
+  // Serve a simple text file or HTML with minimal headers
+  res.type('text/plain');
+  res.send('Hello, World!');
+});
+
+app.listen(port, () => {
+  console.log(`Server running on port ${port}`);
+});
+```
+
+**Testing the Setup:**
+
+1. **Run the server**:
+
+```bash
+node server.js
+```
+
+2. **Manually inspect headers** using browser developer tools:
+
+- Open your web browser and navigate to `http://localhost:3000`.
+- Open the browser's developer tools (usually F12 or right-click > Inspect).
+- Go to the Network tab and refresh the page.
+- Click on the request to your server and inspect the headers.
+
+You should see minimal headers being used. If you find unnecessary headers, you can configure your server to remove them by modifying the middleware in your `server.js` file.
+
+For example, if you find that your server is sending a `Server` header and you want to remove it, you could add the following line inside your middleware function:
+
+```javascript
+res.removeHeader("Server");
+```
+
+**Note**: The impact of removing HTTP headers on energy consumption is generally very small, especially for small-scale applications. However, for large-scale applications with millions of requests, even small optimizations can lead to significant savings in bandwidth and energy use. It's also a good practice for security, as it can reduce the amount of information potentially useful to attackers.
\ No newline at end of file

Code-examples/Ex9/server.js

+const express = require('express');
+const app = express();
+const port = 3000;
+
+app.use((req, res, next) => {
+  // Express adds a header "X-Powered-By: Express" by default, but it's not needed
+  res.removeHeader("X-Powered-By");
+  res.removeHeader("Remote Address");
+  next();
+});
+
+app.get('/', (req, res) => {
+  // Serve a simple text file or HTML with minimal headers
+  res.type('text/plain');
+  res.send('Hello, World!');
+});
+
+app.listen(port, () => {
+  console.log(`Server running on port ${port}`);
+});