QPACK: Header Compression for HTTP/3
draft-ietf-quic-qpack-17
QUIC C. Krasic
Internet-Draft Netflix
Intended status: Standards Track M. Bishop
Expires: March 14, 2021 Akamai Technologies
A. Frindell, Ed.
Facebook
September 10, 2020
QPACK: Header Compression for HTTP/3
draft-ietf-quic-qpack-17
Abstract
This specification defines QPACK, a compression format for
efficiently representing HTTP fields, to be used in HTTP/3. This is
a variation of HPACK 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 (mailto:quic@ietf.org)), 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/-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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 14, 2021.
Krasic, et al. Expires March 14, 2021 [Page 1]
Internet-Draft QPACK September 2020
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Conventions and Definitions . . . . . . . . . . . . . . . 4
1.2. Notational Conventions . . . . . . . . . . . . . . . . . 5
2. Compression Process Overview . . . . . . . . . . . . . . . . 5
2.1. Encoder . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1.1. Limits on Dynamic Table Insertions . . . . . . . . . 6
2.1.2. Blocked Streams . . . . . . . . . . . . . . . . . . . 7
2.1.3. Avoiding Flow Control Deadlocks . . . . . . . . . . . 8
2.1.4. Known Received Count . . . . . . . . . . . . . . . . 9
2.2. Decoder . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2.1. Blocked Decoding . . . . . . . . . . . . . . . . . . 9
2.2.2. State Synchronization . . . . . . . . . . . . . . . . 10
2.2.3. Invalid References . . . . . . . . . . . . . . . . . 11
3. Reference Tables . . . . . . . . . . . . . . . . . . . . . . 11
3.1. Static Table . . . . . . . . . . . . . . . . . . . . . . 11
3.2. Dynamic Table . . . . . . . . . . . . . . . . . . . . . . 12
3.2.1. Dynamic Table Size . . . . . . . . . . . . . . . . . 12
3.2.2. Dynamic Table Capacity and Eviction . . . . . . . . . 12
3.2.3. Maximum Dynamic Table Capacity . . . . . . . . . . . 13
3.2.4. Absolute Indexing . . . . . . . . . . . . . . . . . . 13
3.2.5. Relative Indexing . . . . . . . . . . . . . . . . . . 14
3.2.6. Post-Base Indexing . . . . . . . . . . . . . . . . . 15
4. Wire Format . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.1. Primitives . . . . . . . . . . . . . . . . . . . . . . . 15
4.1.1. Prefixed Integers . . . . . . . . . . . . . . . . . . 15
4.1.2. String Literals . . . . . . . . . . . . . . . . . . . 15
4.2. Encoder and Decoder Streams . . . . . . . . . . . . . . . 16
4.3. Encoder Instructions . . . . . . . . . . . . . . . . . . 17
4.3.1. Set Dynamic Table Capacity . . . . . . . . . . . . . 17
4.3.2. Insert With Name Reference . . . . . . . . . . . . . 18
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