--:-- --
↓ Scroll for more

Unit 7.4

Understanding Client-Server Architecture

IT 231: IT and Application

Learning Objectives 🎯

By the end of this chapter, you will be able to:

  • ✅ Define client-server architecture.
  • ✅ Describe the role of a client.
  • ✅ Describe the role of a server.
  • ✅ Explain the request-response model.

The Foundation of the Modern Internet

Client-Server Architecture: A computing model where a central server hosts, delivers, and manages resources and services for one or more clients.

Think of it as a restaurant: you (the client) order from the kitchen (the server).

The Two Key Players 📊

The Client

Requests services.

Interacts directly with the end-user.

Examples: Web Browser, Mobile App, Email Client (Outlook)

The Server

Provides services.

Waits for and responds to client requests.

Examples: Web Server, Database Server, Mail Server

🔍 Deep Dive: The Client

The client is any computer or program that requests services or resources from a server.

Example: Your Web Browser

When you type www.google.com into Chrome, Firefox, or Safari...

...your browser acts as the client, sending a request for the Google homepage.

⚡ Deep Dive: The Server

The server is a powerful computer or program dedicated to providing services to clients.

Web Server

Stores website files (HTML, CSS, images) and "serves" them to browsers upon request.

Mail Server

Manages the sending, receiving, and storing of emails for clients like Gmail or Outlook.

Servers are designed to handle many requests at once and run 24/7.

The Request-Response Model

This is the core communication cycle of the client-server architecture.

  1. 1. Request: The Client sends a request to the Server.
    (e.g., "Get me the homepage for ekantipur.com")
  2. 2. Process: The Server receives the request, finds the necessary resources, and processes it.
    (e.g., Locates the HTML file for the homepage)
  3. 3. Response: The Server sends a response back to the Client.
    (e.g., The HTML, CSS, and image files for the page)

Visualizing the Cycle

1. Client Request

💻➡️🌐

Your browser asks for a website.

2. Server Processes

⚙️🗄️

The web server finds the requested files.

3. Server Response

💻⬅️🌐

The server sends the website data back.

This entire cycle often happens in milliseconds!

Practical Application in Nepal

Using eSewa or Khalti

Client: Your smartphone app (the eSewa/Khalti app).

Request: You tap "Pay" for your NTC mobile top-up.

Server: The eSewa/Khalti server receives the request, validates your account, securely communicates with the NTC server, and processes the payment.

Response: The server sends a "Transaction Successful" message back to your app.

Key Takeaways

  • Client-server is the fundamental architecture of the internet.
  • The client is the requester (e.g., your browser).
  • The server is the provider (e.g., a web server).
  • All communication happens through a simple but powerful request-response cycle.

Discussion Questions

  1. When you use a mobile app like Instagram, which part is the client and which part is the server?
  2. What are some of the advantages of the client-server model? (Think about centralization, security, and maintenance).
  3. Can a computer be both a client and a server? Explain.

Thank You!

Any questions?

Next Topic: Unit 8.1 - Introduction to Networking Protocols

Return to IT 231 Course Home