Node.js Server Communication

Introduction

• Server-side code powered by Node.js and JavaScript.
• Creates a website that listens for incoming requests from a browser.

The Process of Communication

• Request Initiation:
  • Type a website address in a browser and hit enter.
  • This sends a request to the server powering that website.
• Server Response:
  • The server processes the request and sends back a response (typically an HTML page).
  • Can also send images, CSS, JSON, etc.

IP Addresses and Domains

• IP Addresses:
  • Unique addresses identifying computers on the Internet.
  • Hosts have IP addresses hosting websites.
• Domain Names:
  • Mask IP addresses for easier access.
  • When a domain name is typed into a browser, it resolves to the associated IP address.

Types of Requests

• GET Requests:
  • Made automatically when navigating to a webpage or clicking links.
• POST Requests:
  • Used to send data to servers (e.g., submitting forms).
• HTTP Protocol:
  • Stands for Hypertext Transfer Protocol.
  • A set of instructions for communication between clients (browsers) and servers.

Creating a Server with Node.js

• Server is manually created in Node.js using the http module.
• Server Creation Steps:
  1. Require the HTTP module:

     const http = require('http');
     

  2. Create the server using http.createServer(), which accepts a callback function to handle requests.
  3. The callback function provides:
     • Request Object: Contains information about the request (e.g., URL, request type).
     • Response Object: Used to send a response back to the browser.
  4. Log message to console upon receiving requests:

     console.log('Request made');
     

• Listening for Requests:
  • Use server.listen(port, hostname, callback):
    • Example: server.listen(3000, 'localhost', () => { console.log('Listening on port 3000'); });
  • Localhost:
    • Refers to the loopback IP address (127.0.0.1), connecting to your own computer.
  • Port Numbers:
    • Represents specific channels for software communication.
    • Commonly used port number for local development is 3000.

Running the Server

• Run the server file using Node.js:

  node server.js
  

• The server will now listen for requests at localhost:3000.
• Press Ctrl + C to stop the server.

Testing the Server

• Open a browser and navigate to http://localhost:3000.
• The request will be logged in the terminal, but no response will be sent yet.

Sending Responses to the Browser

• The next lesson will cover how to use the response object to send data back to the browser.