HTTP Server Events in Node.js

HTTP Server objects provide the foundation for creating web servers in Node.js. They handle TCP socket operations, request processing, and response delivery. Key events include:

• request: Triggered when a client request arives (callback: request, response)
• connection: Fires on new TCP stream establishment (callback: socket)
• close: Emitted when server shuts down (no parameters)
• checkContinue: Handles Expect: 100-continue headers (callback: request, response)
• connect: Processes HTTP CONNECT requests (callback: request, response, head)
• upgrade: Manages HTTP upgrade requests (callback: request, response, head)
• clientError: Handles client connection errors (callback: error, socket)

Server Initialization Methods

const server = require('http').createServer();
server.listen(3000, 'localhost', 512, () => {
  console.log('Server active on port 3000');
});

Alternative binding methods:

server.listen('/tmp/server.sock');
server.listen({fd: 12}); // Using file descriptor

GET Request Implementation

Server-Side Code

const http = require('http');
const greetings = ['Welcome', 'Node.js HTTP Server', 'Hello World'];

http.createServer((req, res) => {
  res.setHeader('Content-Type', 'text/html');
  res.writeHead(200);
  res.write('<html><body>');
  greetings.forEach(text => {
    res.write(`<h1>${text}</h1>`);
  });
  res.end('</body></html>');
}).listen(3000);

Client-Side Request

const http = require('http');
const clientOptions = {
  host: 'localhost',
  port: 3000,
  path: '/'
};

http.request(clientOptions, response => {
  let dataChunks = [];
  
  response.on('data', chunk => {
    dataChunks.push(chunk);
  });
  
  response.on('end', () => {
    console.log('Status:', response.statusCode);
    console.log('Headers:', response.headers);
    console.log(Buffer.concat(dataChunks).toString());
  });
}).end();

POST Request Implementation

Server Handling

const http = require('http');

http.createServer((req, res) => {
  let requestBody = '';
  
  req.on('data', chunk => {
    requestBody += chunk;
  });
  
  req.on('end', () => {
    const parsedData = JSON.parse(requestBody);
    const responseData = {
      greeting: `Hello ${parsedData.username}`,
      query: `Are you a ${parsedData.job}?`
    };
    res.writeHead(200, {'Content-Type': 'application/json'});
    res.end(JSON.stringify(responseData));
  });
}).listen(3001);

Client POST Request

const http = require('http');
const postOptions = {
  host: '127.0.0.1',
  port: 3001,
  method: 'POST',
  headers: {'Content-Type': 'application/json'}
};

const postRequest = http.request(postOptions, response => {
  let responseBuffer = '';
  
  response.on('data', chunk => {
    responseBuffer += chunk;
  });
  
  response.on('end', () => {
    const result = JSON.parse(responseBuffer);
    console.log('Server Response:', result);
  });
});

postRequest.write('{"username":"Gandalf", "job":"Wizard"}');
postRequest.end();