How are QUIC and HTTP/3 Related?
QUIC was originally a Google effort to improve HTTP/2 by transporting it encrypted over UDP. In 2016, the IETF began working to standardize the protocol. Part of that process involved splitting QUIC into the transport and application protocols. For some time, the application protocol was referred to as HTTP-over-QUIC, but in November of 2018, the IETF announced that HTTP-over-QUIC would be called HTTP/3.
The IETF is still defining what HTTP/3 will look like. There will be several iterations of review and revision before a standard is adopted, and LiteSpeed, on of the servers we support and we install on some of our clients will continue to be involved every step of the way. LiteSpeed goal is to be the first to offer a production-ready HTTP/3 server implementation. We did it with SPDY, HTTP/2, and QUIC, and we can do it again!
LiteSpeed goal is to be the first to offer a production-ready HTTP/3 server implementationLiteSpeed Server
Usage statistics of HTTP/2 for websites
This diagram shows the market position of HTTP/2 in terms of popularity and traffic compared to the most popular site elements.
Popular sites using HTTP/2
HTTP/3 Hypertext Transfer Protocol Version 3 (HTTP/3)
The QUIC transport protocol has several features that are desirable in a transport for HTTP, such as stream multiplexing, per-stream flow control, and low-latency connection establishment. This document describes a mapping of HTTP semantics over QUIC. This document also identifies HTTP/2 features that are subsumed by QUIC, and describes how HTTP/2 extensions can be ported to HTTP/3.
Discussion of this draft takes place on the QUIC working group mailing list ([email protected]), which is archived at https://mailarchive.ietf.org/arch/search/?email_list=quic.
Working Group information can be found at https://github.com/quicwg; source code and issues list for this draft can be found at https://github.com/quicwg/base-drafts/labels/-http.
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.
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This Internet-Draft will expire on December 26, 2019.
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HTTP semantics are used for a broad range of services on the Internet. These semantics have commonly been used with two different TCP mappings, HTTP/1.1 and HTTP/2. HTTP/3 supports the same semantics over a new transport protocol, QUIC.
HTTP/1.1 is a TCP mapping which uses whitespace-delimited text fields to convey HTTP messages. While these exchanges are human-readable, using whitespace for message formatting leads to parsing difficulties and workarounds to be tolerant of variant behavior. Because each connection can transfer only a single HTTP request or response at a time in each direction, multiple parallel TCP connections are often used, reducing the ability of the congestion controller to accurately manage traffic between endpoints.
HTTP/2 introduced a binary framing and multiplexing layer to improve latency without modifying the transport layer. However, because the parallel nature of HTTP/2’s multiplexing is not visible to TCP’s loss recovery mechanisms, a lost or reordered packet causes all active transactions to experience a stall regardless of whether that transaction was impacted by the lost packet.
The QUIC transport protocol incorporates stream multiplexing and per-stream flow control, similar to that provided by the HTTP/2 framing layer. By providing reliability at the stream level and congestion control across the entire connection, it has the capability to improve the performance of HTTP compared to a TCP mapping. QUIC also incorporates TLS 1.3 at the transport layer, offering comparable security to running TLS over TCP, with the improved connection setup latency of TCP Fast Open [RFC7413]}.
This document defines a mapping of HTTP semantics over the QUIC transport protocol, drawing heavily on the design of HTTP/2. While delegating stream lifetime and flow control issues to QUIC, a similar binary framing is used on each stream. Some HTTP/2 features are subsumed by QUIC, while other features are implemented atop QUIC.
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