HTTP 1 Vs HTTP 2 Vs HTTP 3!

Summary

This video explores the evolution of HTTP, the protocol that powers the web. Starting from HTTP 0.9's simplicity to HTTP 1.0's introduction of headers and methods, it details how HTTP 1.1 improved efficiency with persistent connections and pipelining. It then delves into HTTP 2's binary framing and multiplexing, addressing head-of-line blocking. Finally, it covers HTTP 3's use of QUIC over UDP for reduced latency and better mobile performance, highlighting the continuous adaptation to meet the growing demands of web speed and reliability.

Takeaways

• 🌐 HTTP (Hypertext Transfer Protocol) is the backbone of the web, allowing browsers to communicate with web servers.
• 📚 HTTP initially stood for hypertext documents but has evolved to handle images, videos, APIs, and more.
• 🔍 HTTP 0.9 was the earliest version, supporting only GET requests and HTML files without headers.
• 🚀 HTTP 1.0 introduced headers, status codes, and new methods like POST and HEAD, improving upon HTTP 0.9.
• 🔄 HTTP 1.1, released in 1997, featured persistent connections and pipelining, reducing the overhead of multiple TCP handshakes.
• 🔁 Pipelining in HTTP 1.1 allowed multiple requests to be sent over a single TCP connection without waiting for each response.
• 📈 HTTP 1.1 also improved caching with headers like Cache-Control and ETag, and conditional requests with If-Modified-Since.
• 🚧 HTTP 1.1 faced issues like head-of-line blocking, leading to workarounds like domain sharding and resource bundling.
• 🚀 HTTP 2, introduced in 2015, offered binary framing, multiplexing, stream prioritization, server push, and header compression.
• 🔄 HTTP 2's multiplexing solved the head-of-line blocking problem by allowing interleaved transmission of request and response frames.
• 🌐 HTTP 3, standardized in 2022, uses QUIC over UDP to reduce latency, improve multiplexing, and handle mobile networks better.
• 📈 HTTP 3's use of QUIC allows for faster connection setup and better performance on high latency or lossy networks.

Q & A

What does HTTP stand for and what is its primary function?

HTTP stands for Hypertext Transfer Protocol, and its primary function is to facilitate communication between browsers and web servers, allowing browsers to request web pages and receive them in response.

How did HTTP evolve from HTTP 0.9 to HTTP 1?

HTTP evolved from HTTP 0.9, which only supported GET requests and sent HTML files without headers or status codes, to HTTP 1.0, which introduced headers, status codes, and new methods like POST and HEAD, making it more versatile and efficient.

What was the main inefficiency in HTTP 1.0?

The main inefficiency in HTTP 1.0 was that each request required its own connection, leading to a lot of back-and-forth communication, which was not ideal due to the need for multiple TCP handshakes for every resource like images, CSS files, or JavaScript files.

What improvements did HTTP 1.1 bring over HTTP 1.0?

HTTP 1.1 introduced persistent connections, which kept connections open unless explicitly closed, reducing the need for multiple TCP handshakes. It also introduced pipelining, allowing clients to send multiple requests over one TCP connection without waiting for responses, and chunk transfer encoding, which enabled servers to send responses in smaller chunks for faster initial page rendering.

Why did some browsers not use pipelining in HTTP 1.1?

Some browsers did not use pipelining in HTTP 1.1 because of the head-of-line blocking issue, where if the first request in the pipeline was delayed, all subsequent requests would also be blocked, negating the benefits of pipelining.

What strategies were used to work around the limitations of HTTP 1.1?

To work around the limitations of HTTP 1.1, strategies like domain sharding, where static assets were served from subdomains to get more connections, and asset bundling, where images were combined using sprites and CSS and JavaScript files were concatenated, were employed.

How does HTTP 2 improve upon HTTP 1.1?

HTTP 2 introduced a binary framing layer, full request and response multiplexing to fix head-of-line blocking, stream prioritization to set the importance of requests, server push to send extra resources along with the requested page, and header compression using HPACK to make headers smaller and more efficient.

What are the key benefits of using QUIC, the protocol HTTP 3 is built upon?

QUIC, the protocol HTTP 3 is built upon, reduces latency, improves multiplexing without TCP head-of-line blocking, handles packet loss better, and performs better on mobile networks with seamless connection changes.

How does HTTP 3 handle network changes such as switching from Wi-Fi to cellular?

HTTP 3 handles network changes effectively by using QUIC's connection IDs, which do not depend on IP addresses. This allows the connection to continue even when the client switches from Wi-Fi to cellular, maintaining the connection without interruption.

What is the current adoption rate of HTTP 3 compared to HTTP 1.1 and HTTP 2?

As of 2023, HTTP 1.1 is still widely used, especially for simple websites, while HTTP 2 handles over 60% of web requests according to some estimates. HTTP 3 is relatively new but is gaining traction, with big companies like Google and Cloudflare leading its adoption.