The Client-Server Model is a foundational concept in the HTTP protocol, whereby a client requests resources from a server, which processes the request and returns the desired data. This model enables web applications to function by distinguishing the roles of client and server.

2.1 Definitions

• Client: A device or application that requests resources from a server.
• Server: A system that processes requests and sends responses back to clients.
• HTTP (Hypertext Transfer Protocol): The protocol used for transferring hypertext requests and information on the internet.

2.2 Interaction Flow

The interaction between client and server can be summarized in the following steps:

1. Client initiates an HTTP request.
2. Request is sent to the server.
3. Server processes the request.
4. Server sends back an HTTP response.

3.1 Request Creation

The client creates an HTTP request to access a resource:

GET /index.html HTTP/1.1
Host: www.example.com
User-Agent: Mozilla/5.0
Accept: text/html

3.2 Request Transmission

The request is sent over the network to the server via a Transmission Control Protocol (TCP) connection.

3.3 Server Processing

The server processes the request, accessing any necessary data or resources.

3.4 Response Creation

The server creates an HTTP response:

HTTP/1.1 200 OK
Content-Type: text/html
Content-Length: 1234




Hello, World!