HPACK - Header Compression for HTTP/2
draft-ietf-httpbis-header-compression-08

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HTTPbis Working Group                                            R. Peon
Internet-Draft                                               Google, Inc
Intended status: Standards Track                              H. Ruellan
Expires: December 19, 2014                                     Canon CRF
                                                           June 17, 2014

                 HPACK - Header Compression for HTTP/2
                draft-ietf-httpbis-header-compression-08

Abstract

   This specification defines HPACK, a compression format for
   efficiently representing HTTP header fields in the context of HTTP/2.

Editorial Note (To be removed by RFC Editor)

   Discussion of this draft 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/>.

   Working Group information can be found at <http://tools.ietf.org/wg/
   httpbis/>; that specific to HTTP/2 are at <http://http2.github.io/>.

   The changes in this draft are summarized in Appendix A.1.

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 December 19, 2014.

Peon & Ruellan          Expires December 19, 2014               [Page 1]
Internet-Draft                    HPACK                        June 2014

Copyright Notice

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   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  HPACK Overview  . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Outline . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.2.  Conventions . . . . . . . . . . . . . . . . . . . . . . .   5
     2.3.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  Decoding Process Overview . . . . . . . . . . . . . . . . . .   6
     3.1.  Encoding and Decoding Contexts  . . . . . . . . . . . . .   6
     3.2.  Header Table  . . . . . . . . . . . . . . . . . . . . . .   6
     3.3.  Reference Set . . . . . . . . . . . . . . . . . . . . . .   7
     3.4.  Header Field Representation . . . . . . . . . . . . . . .   7
     3.5.  Header Field Emission . . . . . . . . . . . . . . . . . .   9
   4.  Header Block Decoding . . . . . . . . . . . . . . . . . . . .   9
     4.1.  Header Field Representation Processing  . . . . . . . . .   9
     4.2.  Reference Set Emission  . . . . . . . . . . . . . . . . .  10
   5.  Header Table Management . . . . . . . . . . . . . . . . . . .  10
     5.1.  Maximum Table Size  . . . . . . . . . . . . . . . . . . .  10
     5.2.  Entry Eviction When Header Table Size Changes . . . . . .  11
     5.3.  Entry Eviction when Adding New Entries  . . . . . . . . .  12
   6.  Primitive Type Representations  . . . . . . . . . . . . . . .  12
     6.1.  Integer representation  . . . . . . . . . . . . . . . . .  12
     6.2.  String Literal Representation . . . . . . . . . . . . . .  13
   7.  Binary Format . . . . . . . . . . . . . . . . . . . . . . . .  14
     7.1.  Indexed Header Field Representation . . . . . . . . . . .  14
     7.2.  Literal Header Field Representation . . . . . . . . . . .  15
       7.2.1.  Literal Header Field with Incremental Indexing  . . .  15
       7.2.2.  Literal Header Field without Indexing . . . . . . . .  16
       7.2.3.  Literal Header Field Never Indexed  . . . . . . . . .  17
     7.3.  Encoding Context Update . . . . . . . . . . . . . . . . .  18
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  19
     8.1.  Probing Header Table State  . . . . . . . . . . . . . . .  20
       8.1.1.  Applicability to HPACK and HTTP . . . . . . . . . . .  20
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