Hypertext Transfer Protocol Version 2 (HTTP/2)
draft-ietf-httpbis-http2bis-01
HTTPbis M. Thomson, Ed.
Internet-Draft Mozilla
Obsoletes: 7540, 8740 (if approved) C. Benfield, Ed.
Intended status: Standards Track Apple Inc.
Expires: 26 August 2021 22 February 2021
Hypertext Transfer Protocol Version 2 (HTTP/2)
draft-ietf-httpbis-http2bis-01
Abstract
This specification describes an optimized expression of the semantics
of the Hypertext Transfer Protocol (HTTP), referred to as HTTP
version 2 (HTTP/2). HTTP/2 enables a more efficient use of network
resources and a reduced perception of latency by introducing header
field compression and allowing multiple concurrent exchanges on the
same connection. It also introduces unsolicited push of
representations from servers to clients.
This specification is an alternative to, but does not obsolete, the
HTTP/1.1 message syntax. HTTP's existing semantics remain unchanged.
Discussion Venues
Discussion of this document takes place on the HTTPBIS Working Group
mailing list (ietf-http-wg@w3.org), which is archived at
https://lists.w3.org/Archives/Public/ietf-http-wg/.
This note is to be removed before publishing as an RFC.
Source for this draft and an issue tracker can be found at
https://github.com/httpwg/http2-spec.
Status of This Memo
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
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Internet-Drafts are draft documents valid for a maximum of six months
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time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
Thomson & Benfield Expires 26 August 2021 [Page 1]
Internet-Draft HTTP/2 February 2021
This Internet-Draft will expire on 26 August 2021.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
2. HTTP/2 Protocol Overview . . . . . . . . . . . . . . . . . . 5
2.1. Document Organization . . . . . . . . . . . . . . . . . . 6
2.2. Conventions and Terminology . . . . . . . . . . . . . . . 6
3. Starting HTTP/2 . . . . . . . . . . . . . . . . . . . . . . . 7
3.1. HTTP/2 Version Identification . . . . . . . . . . . . . . 7
3.2. Starting HTTP/2 for "http" URIs . . . . . . . . . . . . . 8
3.2.1. HTTP2-Settings Header Field . . . . . . . . . . . . . 9
3.3. Starting HTTP/2 for "https" URIs . . . . . . . . . . . . 10
3.4. Starting HTTP/2 with Prior Knowledge . . . . . . . . . . 10
3.5. HTTP/2 Connection Preface . . . . . . . . . . . . . . . . 11
4. HTTP Frames . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.1. Frame Format . . . . . . . . . . . . . . . . . . . . . . 12
4.2. Frame Size . . . . . . . . . . . . . . . . . . . . . . . 13
4.3. Field Section Compression and Decompression . . . . . . . 14
5. Streams and Multiplexing . . . . . . . . . . . . . . . . . . 15
5.1. Stream States . . . . . . . . . . . . . . . . . . . . . . 16
5.1.1. Stream Identifiers . . . . . . . . . . . . . . . . . 21
5.1.2. Stream Concurrency . . . . . . . . . . . . . . . . . 22
5.2. Flow Control . . . . . . . . . . . . . . . . . . . . . . 22
5.2.1. Flow-Control Principles . . . . . . . . . . . . . . . 23
5.2.2. Appropriate Use of Flow Control . . . . . . . . . . . 24
5.3. Stream Priority . . . . . . . . . . . . . . . . . . . . . 24
5.3.1. Stream Dependencies . . . . . . . . . . . . . . . . . 25
5.3.2. Dependency Weighting . . . . . . . . . . . . . . . . 26
5.3.3. Reprioritization . . . . . . . . . . . . . . . . . . 26
5.3.4. Prioritization State Management . . . . . . . . . . . 27
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