QPACK: Header Compression for HTTP/3
draft-ietf-quic-qpack-12
QUIC C. Krasic
Internet-Draft Netflix
Intended status: Standards Track M. Bishop
Expires: 25 July 2020 Akamai Technologies
A. Frindell, Ed.
Facebook
22 January 2020
QPACK: Header Compression for HTTP/3
draft-ietf-quic-qpack-12
Abstract
This specification defines QPACK, a compression format for
efficiently representing HTTP header fields, to be used in HTTP/3.
This is a variation of HPACK header compression that seeks to reduce
head-of-line blocking.
Note to Readers
Discussion of this draft takes place on the QUIC working group
mailing list (quic@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/search/?email_list=quic
(https://mailarchive.ietf.org/arch/search/?email_list=quic).
Working Group information can be found at https://github.com/quicwg
(https://github.com/quicwg); source code and issues list for this
draft can be found at https://github.com/quicwg/base-drafts/labels/-
qpack (https://github.com/quicwg/base-drafts/labels/-qpack).
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
Task Force (IETF). Note that other groups may also distribute
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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."
This Internet-Draft will expire on 25 July 2020.
Krasic, et al. Expires 25 July 2020 [Page 1]
Internet-Draft QPACK January 2020
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions and Definitions . . . . . . . . . . . . . . . 4
1.2. Notational Conventions . . . . . . . . . . . . . . . . . 4
2. Compression Process Overview . . . . . . . . . . . . . . . . 5
2.1. Encoder . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1.1. Reference Tracking . . . . . . . . . . . . . . . . . 6
2.1.2. Limits on Dynamic Table Insertions . . . . . . . . . 6
2.1.3. Blocked Streams . . . . . . . . . . . . . . . . . . . 7
2.1.4. Known Received Count . . . . . . . . . . . . . . . . 8
2.2. Decoder . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2.1. Blocked Decoding . . . . . . . . . . . . . . . . . . 8
2.2.2. State Synchronization . . . . . . . . . . . . . . . . 9
2.2.3. Invalid References . . . . . . . . . . . . . . . . . 10
3. Header Tables . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1. Static Table . . . . . . . . . . . . . . . . . . . . . . 10
3.2. Dynamic Table . . . . . . . . . . . . . . . . . . . . . . 11
3.2.1. Dynamic Table Size . . . . . . . . . . . . . . . . . 11
3.2.2. Dynamic Table Capacity and Eviction . . . . . . . . . 11
3.2.3. Maximum Dynamic Table Capacity . . . . . . . . . . . 12
3.2.4. Absolute Indexing . . . . . . . . . . . . . . . . . . 12
3.2.5. Relative Indexing . . . . . . . . . . . . . . . . . . 12
3.2.6. Post-Base Indexing . . . . . . . . . . . . . . . . . 14
4. Wire Format . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.1. Primitives . . . . . . . . . . . . . . . . . . . . . . . 14
4.1.1. Prefixed Integers . . . . . . . . . . . . . . . . . . 14
4.1.2. String Literals . . . . . . . . . . . . . . . . . . . 14
4.2. Encoder and Decoder Streams . . . . . . . . . . . . . . . 15
4.3. Encoder Instructions . . . . . . . . . . . . . . . . . . 16
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