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GET /path/to/resource HTTP/1.1
Host: example.com
User-Agent: Browser/Version

HTTP Overview:

  • Full Form: Hypertext Transfer Protocol
  • Purpose: Transfer hypertext links (web documents)
  • Definition: Set of rules for data communication
  • Key Characteristics:
    • Human-readable
    • Stateless protocol
    • No memory of previous requests
  • Behavior: Processes each page/request as new, without maintaining user state
  • Purpose: Maintain user state between frontend and backend
  • Key Characteristics:
    • Shared between browser (client) and server
    • Bidirectional communication
  • Cookie Functionality:
    • Server can send cookie to browser
    • Browser can send cookie to server
    • Transfers information/data between systems
  • Core Concept: Enables persistent user information exchange

Web Request-Response Model:

Key Components:

  1. Action Type (HTTP Methods)

    • GET
    • POST
    • DELETE
    • PUT

  2. Location (URL)

  3. Response Status

    • Indicates action completion
    • Response Codes Example:
      • 200: Successful
      • 404: Not Found
      • 500: Server Error
      • 403: Forbidden
      • 302: Redirect

Core Concept:

  • Browser sends request to server
  • Server processes request
  • Server sends back response
  • Response indicates whether action was successful

Understanding HTTP/2: Modern Web Communication Protocol

Overview of HTTP Versions

HTTP/2 represents the modern standard for web communication, with HTTP/1.1 serving as the primary fallback protocol. Interestingly, HTTP version 1 was never officially released, with HTTP/1.1 being the predecessor to the current HTTP/2.

Key Features of HTTP/2

1. Data Compression

HTTP/2 introduces significant improvements in data transfer efficiency through compression. This means:

  • Data is compressed (zipped) during transfer
  • Reduced data size
  • Faster request and response processing

2. Multiplexing

A revolutionary feature of HTTP/2 is its ability to handle multiple requests simultaneously:

  • Can manage multiple request-response cycles concurrently

  • It used a single TCP connection between the client and the server for a given origin, this allowed for a faster transfer for the data.

  • Overcomes limitations of HTTP/1.1, where:

    • Only one request could be processed at a time
    • A single user was restricted to one request-response cycle

Protocol Evolution

  • HTTP/1.1: Initial standard protocol
  • HTTP/2: Current modern web communication protocol
  • Fallback mechanism ensures compatibility with older systems

The introduction of HTTP/2 significantly improves web communication efficiency, reducing latency and enhancing overall performance.

Understanding Basic HTTP/HTTPS Communication

Initial Connection Establishment

When a browser initiates communication with a server, the process begins with a crucial security step:

  1. TLS Handshake
    • The browser and server exchange TLS (Transport Layer Security) certificates
    • This ensures a secure, encrypted connection

Request Transmission

The browser sends a comprehensive request to the server, which typically includes:

  • HTTP method (e.g., GET, POST)
  • Complete URL
  • Additional request headers
  • Potential request data

Server Response

The server processes the request and responds with:

  • Status code (indicating request success or failure)
  • Response body
  • TCP connection details

Key Characteristic: Stateless Communication

Important Note: HTTP is fundamentally stateless, meaning each request-response cycle is independent. The server does not inherently maintain information about previous interactions.