? Client–Server Architecture

? Quick Overview

Client–Server Architecture is a computing model where multiple clients request services or resources from a centralized server. The interaction is based on a request–response cycle, commonly used in web applications, APIs, and distributed systems.

? Key Concepts

Client – Initiates requests (browser, mobile app, Postman)
Server – Processes requests and sends responses
Request–Response Model – Communication pattern
Statelessness – Each request is independent
Protocol – Usually HTTP/HTTPS

? Syntax / Theory

In client–server systems, the client sends an HTTP request to a server endpoint. The server processes the request, interacts with databases or services, and returns an HTTP response containing status codes and data.

? Code Example (HTTP Request)

? View Code Example

// Client sending an HTTP GET request using fetch API
fetch("https://api.example.com/users")
.then(response => response.json())
.then(data => console.log(data))
.catch(error => console.error(error));

? Live Output / Explanation

Response Flow

The client sends a GET request → Server processes it → Server sends back JSON data → Client displays or uses the data.

? Interactive Simulation

Client

Browser

➡️

Server

Idle

> System ready... waiting for user input.

? Interactive Diagram

? Use Cases

Web applications
REST APIs
Mobile backend services
Cloud-based systems

✅ Tips & Best Practices

Keep servers stateless for scalability
Use proper HTTP status codes
Secure communication with HTTPS
Cache responses where possible

? Try It Yourself

Use Postman to send GET and POST requests to a public API. Observe headers, status codes, and JSON responses.