What is HTTP/3? How it is Different From HTTP/2?

Web protocols are important for transmitting data from client to server over the web. Over time various developments were made to enhance the efficiency, performance, and safety of web protocols. HTTP/2 and HTTP/3 provide various features to transmit data over the internet or web. In this article, we are going to discuss the HTTP, HTTP/2, and HTTP/3 and the comparison between HTTP/2 and HTTP/3.

What is HTTP?

HTTP stands for Hypertext Transfer Protocol, it is a protocol through which hypertext is transferred over the web. Hypertext Transfer Protocol was invented by Tim Berner in 1989. The World Wide Web allows people to share data like text, photos, and multimedia files. When a user opens their web browser, they indirectly use HTTP.

Advantages of HTTP

• HTTP allows HTTP pipe-lining of requests or responses.
• Memory and CPU usage is low.
• Since there are few TCP connections hence network congestion is less.
• The error can be reported without closing the connection.

Disadvantages of HTTP

• HTTP suffers from a Head of Line Blocking problem(Head of Line blocking refers to the situation in which a browser/client must wait for previous requests to complete, before sending another).
• HTTP requires high power to establish communication and transfer data.
• HTTP is less secure.
• HTTP is used for point-to-point connection only.
• HTTP is not optimized for mobile phones.
• HTTP does not offer reliable communication.

What is HTTP/2 – A Solution to HTTP?

HTTP/2 was released in 2015, it addresses the HOL(Head of Line Blocking) issue through request multiplexing, which eliminates HOL blocking at the application layer but HOL still exists at the transport layer. HTTP/2 decreases performance limitations while maintaining compatibility with existing applications. HTTP/2 improves network resources reduces latency by reducing header fields and allows concurrent exchanges on a single connection. It enables request prioritization, allowing more critical requests to be completed faster, which improves the speed during communication.

Features of HTTP/2

• One of the important features of HTTP/2 is multiplexing. Multiplexing allows several requests and responses to be sent over a single connection, which improves performance by reducing connection overhead and improving network resource utilization.
• Unlike HTTP which is a text-based protocol, HTTP/2 uses a binary protocol, which reduces data size and improves efficiency.
• HTTP/2 enables servers to proactively “push” responses into client caches rather than waiting for a new request for each resource.
• HTTP/2 decreases extra Round Trip Time(RTT), allowing your website to load faster without any optimization.
• HTTP/2 reduced network latency and increased throughput.
• HTTP/2 supports response prioritization, flow control, and good handling of Transport Layer Security(TLS).

Problems with HTTP/2

• The implementation of HTTP/2 is more complex because of the addition of new features like multiplexing, header compression, and stream prioritization.
• TLS introduces additional latency in HTTP/2.
• HTTP/2 also suffers from the Head of Line Blocking problem.
• TCP dependency and strict network situations may lead to interoperability issues.

HTTP/3 – Establishing the Future

HTTP/3 is a major advancement over HTTP/2. HTTP/3 aims to enable fast, reliable, and secure web connections across all types of devices by resolving HTTP/2’s transport-related problems. To do this, it employs a separate transport layer network protocol known as QUIC (Quick UDP Internet Connections), which operates on the User Datagram Protocol (UDP) internet than the TCP used by all prior versions of HTTP. Unlike TCP’s, UDP supports multidirectional broadcasting of data, which resolves the issue of head-of-line blocking (HOL).

Define QUIC?

QUIC(Quick UDP Internet Connections) is also supposed to be extremely quick because it uses 0-RTT and 1-RTT (Round Trip Time) handshakes instead of TCP 3-way handshakes. QUIC ensures faster and more accurate data transmission. This stability, along with speed, provides enhanced congestion control and stream retransmission. The fundamental accusation made about HTTP/3, that it uses UDP, a rather unreliable transmission technology, is eliminated by these features.

Benefits of HTTP/3 over HTTP/2

• HTTP/3 provides many benefits over HTTP/2 for online applications, particularly in terms of performance, security, and compatibility.
• HTTP/3 Improves congestion control mechanism over HTTP/2.
• HTTP/3 removes the need for repeated TCP handshakes that allow faster connection establishment and a connection time reduction of up to 80%-90%.
• The loss recovery and congestion control techniques in QUIC make HTTP/3 more resilient to packet loss and network disturbances.
• HTTP/3 aims to be more compatible with current network infrastructure and devices by employing UDP as port number 443. As a result, browsers including Chrome, Firefox, and Safari now support HTTP/3.

Challenges of HTTP/3 Implementation

• HTTP/3 is built on QUIC which introduces some additional complexity compared to HTTP/2.
• To transit onto HTTP/3, you must modify your current infrastructure, which includes servers and load balancers. Even after moving to HTTP/3, compatibility may still be an issue, particularly if your organization is large or has complex network configurations.
• HTTP/3’s QUIC protocol encrypts data packets from payload to metadata. Encryption is very useful but it makes accessing the data packet challenging. However, firewalls require access to the packet otherwise, clients are vulnerable to cyberattacks.
• Implementing HTTP/3 on the server side requires good knowledge and skills, and you may even need to make changes to your server infrastructure.

HTTP/3 for CDN

CDN stands for Content Delivery Network, it plays an important role in delivering content of web to users across the world effectively. With the release of HTTP/3, CDNs can further enhance their performance, reliability, and security capabilities.

Difference Between HTTP/2 and HTTP/3

Feature	HTTP/2	HTTP/3
Protocol Used	HTTP/2 uses TCP.	HTTP/3 uses QUIC(operate over UDP).
Head of Line Blocking	HTTP/2 suffers from the head of the Line Blocking issue at Transport Layer.	HTTP/3 solves the problem of Head of Line Blocking.
TLS Encryption	TLS Encryption is optional.	TLS is incorporated in QUIC and is the default for HTTP/3.
RFC Used	RFC 9113.	RFC 9114.
Performance	HTTP/2 performance is limited as compared to HTTP/3	HTTP/3 has good performance.
Error Handling	HTTP/2 allows less error-handling capabilities.	QUIC improves error-handling capabilities in HTTP/3.
Connection migration	HTTP/2 does not support connection migration.	HTTP/3 supports connection migration.
Congestion Control	HTTP/2 offers a TCP-based congestion control mechanism.	HTTP/3 offers QUIC-based congestion control mechanisms
Use Case	HTTP/2 is used in most web browsers and servers.	HTTP/3 is emerging as a future standard.

HTTP/2 vs HTTP/3

Conclusion

In Conclusion, HTTP/3 provides greater performance, enhanced security, lower latency, and better management of network situations, making it an appropriate protocol for the future of web communications.

Frequently Asked Question on HTTP/2 and HTTP/3 – FAQs

How to test if my website supports the HTTP/2 and HTTP/3 protocols?

Right-click in the Name column and ensure that the Protocol is checked. there is a protocol column where h2 refers to HTTP/2, h3 refers to HTTP/3, and http/1.1 refers to HTTP/1.1.

Is HTTP/2 backward compatible with HTTP/1.1?

Yes HTTP/2 is backward compatible with HTTP/1.1.

Is HTTP 3 stateless?

HTTP/3 is stateless protocol.

Why is QUIC better than TCP?

QUIC creates connections faster than TCP because it eliminates the round-trip time with a 0-RTT handshake. Another advantage of QUIC over TCP is its greater robustness to network changes due to connection IDs that are not dependent on IP addresses or ports.