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draft-ietf-quic-qpack.html
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draft-ietf-quic-qpack.html
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<!DOCTYPE html>
<html lang="en" class="Internet-Draft">
<head>
<meta charset="utf-8">
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<title>QPACK: Header Compression for HTTP/3</title>
<meta content="Charles 'Buck' Krasic" name="author">
<meta content="Mike Bishop" name="author">
<meta content="Alan Frindell" name="author">
<meta content="
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.
" name="description">
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<body>
<table class="ears">
<thead><tr>
<td class="left">Internet-Draft</td>
<td class="center">QPACK</td>
<td class="right">January 2021</td>
</tr></thead>
<tfoot><tr>
<td class="left">Krasic, et al.</td>
<td class="center">Expires 10 July 2021</td>
<td class="right">[Page]</td>
</tr></tfoot>
</table>
<div id="external-metadata" class="document-information"></div>
<div id="internal-metadata" class="document-information">
<dl id="identifiers">
<dt class="label-workgroup">Workgroup:</dt>
<dd class="workgroup">QUIC</dd>
<dt class="label-internet-draft">Internet-Draft:</dt>
<dd class="internet-draft">draft-ietf-quic-qpack</dd>
<dt class="label-published">Published:</dt>
<dd class="published">
<time datetime="2021-01-06" class="published">6 January 2021</time>
</dd>
<dt class="label-intended-status">Intended Status:</dt>
<dd class="intended-status">Standards Track</dd>
<dt class="label-expires">Expires:</dt>
<dd class="expires"><time datetime="2021-07-10">10 July 2021</time></dd>
<dt class="label-authors">Authors:</dt>
<dd class="authors">
<div class="author">
<div class="author-name">C. Krasic</div>
<div class="org">Netflix</div>
</div>
<div class="author">
<div class="author-name">M. Bishop</div>
<div class="org">Akamai Technologies</div>
</div>
<div class="author">
<div class="author-name">A. Frindell, <span class="editor">Ed.</span>
</div>
<div class="org">Facebook</div>
</div>
</dd>
</dl>
</div>
<h1 id="title">QPACK: Header Compression for HTTP/3</h1>
<section id="section-abstract">
<h2 id="abstract"><a href="#abstract" class="selfRef">Abstract</a></h2>
<p id="section-abstract-1">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.<a href="#section-abstract-1" class="pilcrow">¶</a></p>
</section>
<section class="note" id="section-note.1">
<h2 id="name-note-to-readers">
<a href="#name-note-to-readers" class="section-name selfRef">Note to Readers</a>
</h2>
<p id="section-note.1-1">Discussion of this draft takes place on the QUIC working group mailing list
(<a href="mailto:quic@ietf.org">quic@ietf.org</a>), which is archived at
<span><a href="https://mailarchive.ietf.org/arch/search/?email_list=quic">https://mailarchive.ietf.org/arch/search/?email_list=quic</a></span>.<a href="#section-note.1-1" class="pilcrow">¶</a></p>
<p id="section-note.1-2">Working Group information can be found at <span><a href="https://github.com/quicwg">https://github.com/quicwg</a></span>; source
code and issues list for this draft can be found at
<span><a href="https://github.com/quicwg/base-drafts/labels/-qpack">https://github.com/quicwg/base-drafts/labels/-qpack</a></span>.<a href="#section-note.1-2" class="pilcrow">¶</a></p>
</section>
<div id="status-of-memo">
<section id="section-boilerplate.1">
<h2 id="name-status-of-this-memo">
<a href="#name-status-of-this-memo" class="section-name selfRef">Status of This Memo</a>
</h2>
<p id="section-boilerplate.1-1">
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.<a href="#section-boilerplate.1-1" class="pilcrow">¶</a></p>
<p id="section-boilerplate.1-2">
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 <span><a href="https://datatracker.ietf.org/drafts/current/">https://datatracker.ietf.org/drafts/current/</a></span>.<a href="#section-boilerplate.1-2" class="pilcrow">¶</a></p>
<p id="section-boilerplate.1-3">
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."<a href="#section-boilerplate.1-3" class="pilcrow">¶</a></p>
<p id="section-boilerplate.1-4">
This Internet-Draft will expire on 10 July 2021.<a href="#section-boilerplate.1-4" class="pilcrow">¶</a></p>
</section>
</div>
<div id="copyright">
<section id="section-boilerplate.2">
<h2 id="name-copyright-notice">
<a href="#name-copyright-notice" class="section-name selfRef">Copyright Notice</a>
</h2>
<p id="section-boilerplate.2-1">
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.<a href="#section-boilerplate.2-1" class="pilcrow">¶</a></p>
<p id="section-boilerplate.2-2">
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(<span><a href="https://trustee.ietf.org/license-info">https://trustee.ietf.org/license-info</a></span>) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with
respect to this document. Code Components extracted from this
document must include Simplified BSD License text as described in
Section 4.e of the Trust Legal Provisions and are provided without
warranty as described in the Simplified BSD License.<a href="#section-boilerplate.2-2" class="pilcrow">¶</a></p>
</section>
</div>
<div id="toc">
<section id="section-toc.1">
<a href="#" onclick="scroll(0,0)" class="toplink">▲</a><h2 id="name-table-of-contents">
<a href="#name-table-of-contents" class="section-name selfRef">Table of Contents</a>
</h2>
<nav class="toc"><ul class="ulEmpty toc compact">
<li class="ulEmpty toc compact" id="section-toc.1-1.1">
<p id="section-toc.1-1.1.1" class="keepWithNext"><a href="#section-1" class="xref">1</a>. <a href="#name-introduction" class="xref">Introduction</a><a href="#section-toc.1-1.1.1" class="pilcrow">¶</a></p>
<ul class="ulEmpty toc compact">
<li class="ulEmpty toc compact" id="section-toc.1-1.1.2.1">
<p id="section-toc.1-1.1.2.1.1" class="keepWithNext"><a href="#section-1.1" class="xref">1.1</a>. <a href="#name-conventions-and-definitions" class="xref">Conventions and Definitions</a><a href="#section-toc.1-1.1.2.1.1" class="pilcrow">¶</a></p>
</li>
<li class="ulEmpty toc compact" id="section-toc.1-1.1.2.2">
<p id="section-toc.1-1.1.2.2.1" class="keepWithNext"><a href="#section-1.2" class="xref">1.2</a>. <a href="#name-notational-conventions" class="xref">Notational Conventions</a><a href="#section-toc.1-1.1.2.2.1" class="pilcrow">¶</a></p>
</li>
</ul>
</li>
<li class="ulEmpty toc compact" id="section-toc.1-1.2">
<p id="section-toc.1-1.2.1"><a href="#section-2" class="xref">2</a>. <a href="#name-compression-process-overvie" class="xref">Compression Process Overview</a><a href="#section-toc.1-1.2.1" class="pilcrow">¶</a></p>
<ul class="ulEmpty toc compact">
<li class="ulEmpty toc compact" id="section-toc.1-1.2.2.1">
<p id="section-toc.1-1.2.2.1.1"><a href="#section-2.1" class="xref">2.1</a>. <a href="#name-encoder" class="xref">Encoder</a><a href="#section-toc.1-1.2.2.1.1" class="pilcrow">¶</a></p>
<ul class="ulEmpty toc compact">
<li class="ulEmpty toc compact" id="section-toc.1-1.2.2.1.2.1">
<p id="section-toc.1-1.2.2.1.2.1.1"><a href="#section-2.1.1" class="xref">2.1.1</a>. <a href="#name-limits-on-dynamic-table-ins" class="xref">Limits on Dynamic Table Insertions</a><a href="#section-toc.1-1.2.2.1.2.1.1" class="pilcrow">¶</a></p>
</li>
<li class="ulEmpty toc compact" id="section-toc.1-1.2.2.1.2.2">
<p id="section-toc.1-1.2.2.1.2.2.1"><a href="#section-2.1.2" class="xref">2.1.2</a>. <a href="#name-blocked-streams" class="xref">Blocked Streams</a><a href="#section-toc.1-1.2.2.1.2.2.1" class="pilcrow">¶</a></p>
</li>
<li class="ulEmpty toc compact" id="section-toc.1-1.2.2.1.2.3">
<p id="section-toc.1-1.2.2.1.2.3.1"><a href="#section-2.1.3" class="xref">2.1.3</a>. <a href="#name-avoiding-flow-control-deadl" class="xref">Avoiding Flow Control Deadlocks</a><a href="#section-toc.1-1.2.2.1.2.3.1" class="pilcrow">¶</a></p>
</li>
<li class="ulEmpty toc compact" id="section-toc.1-1.2.2.1.2.4">
<p id="section-toc.1-1.2.2.1.2.4.1"><a href="#section-2.1.4" class="xref">2.1.4</a>. <a href="#name-known-received-count" class="xref">Known Received Count</a><a href="#section-toc.1-1.2.2.1.2.4.1" class="pilcrow">¶</a></p>
</li>
</ul>
</li>
<li class="ulEmpty toc compact" id="section-toc.1-1.2.2.2">
<p id="section-toc.1-1.2.2.2.1"><a href="#section-2.2" class="xref">2.2</a>. <a href="#name-decoder" class="xref">Decoder</a><a href="#section-toc.1-1.2.2.2.1" class="pilcrow">¶</a></p>
<ul class="ulEmpty toc compact">
<li class="ulEmpty toc compact" id="section-toc.1-1.2.2.2.2.1">
<p id="section-toc.1-1.2.2.2.2.1.1"><a href="#section-2.2.1" class="xref">2.2.1</a>. <a href="#name-blocked-decoding" class="xref">Blocked Decoding</a><a href="#section-toc.1-1.2.2.2.2.1.1" class="pilcrow">¶</a></p>
</li>
<li class="ulEmpty toc compact" id="section-toc.1-1.2.2.2.2.2">
<p id="section-toc.1-1.2.2.2.2.2.1"><a href="#section-2.2.2" class="xref">2.2.2</a>. <a href="#name-state-synchronization" class="xref">State Synchronization</a><a href="#section-toc.1-1.2.2.2.2.2.1" class="pilcrow">¶</a></p>
</li>
<li class="ulEmpty toc compact" id="section-toc.1-1.2.2.2.2.3">
<p id="section-toc.1-1.2.2.2.2.3.1"><a href="#section-2.2.3" class="xref">2.2.3</a>. <a href="#name-invalid-references" class="xref">Invalid References</a><a href="#section-toc.1-1.2.2.2.2.3.1" class="pilcrow">¶</a></p>
</li>
</ul>
</li>
</ul>
</li>
<li class="ulEmpty toc compact" id="section-toc.1-1.3">
<p id="section-toc.1-1.3.1"><a href="#section-3" class="xref">3</a>. <a href="#name-reference-tables" class="xref">Reference Tables</a><a href="#section-toc.1-1.3.1" class="pilcrow">¶</a></p>
<ul class="ulEmpty toc compact">
<li class="ulEmpty toc compact" id="section-toc.1-1.3.2.1">
<p id="section-toc.1-1.3.2.1.1"><a href="#section-3.1" class="xref">3.1</a>. <a href="#name-static-table" class="xref">Static Table</a><a href="#section-toc.1-1.3.2.1.1" class="pilcrow">¶</a></p>
</li>
<li class="ulEmpty toc compact" id="section-toc.1-1.3.2.2">
<p id="section-toc.1-1.3.2.2.1"><a href="#section-3.2" class="xref">3.2</a>. <a href="#name-dynamic-table" class="xref">Dynamic Table</a><a href="#section-toc.1-1.3.2.2.1" class="pilcrow">¶</a></p>
<ul class="ulEmpty toc compact">
<li class="ulEmpty toc compact" id="section-toc.1-1.3.2.2.2.1">
<p id="section-toc.1-1.3.2.2.2.1.1"><a href="#section-3.2.1" class="xref">3.2.1</a>. <a href="#name-dynamic-table-size" class="xref">Dynamic Table Size</a><a href="#section-toc.1-1.3.2.2.2.1.1" class="pilcrow">¶</a></p>
</li>
<li class="ulEmpty toc compact" id="section-toc.1-1.3.2.2.2.2">
<p id="section-toc.1-1.3.2.2.2.2.1"><a href="#section-3.2.2" class="xref">3.2.2</a>. <a href="#name-dynamic-table-capacity-and-" class="xref">Dynamic Table Capacity and Eviction</a><a href="#section-toc.1-1.3.2.2.2.2.1" class="pilcrow">¶</a></p>
</li>
<li class="ulEmpty toc compact" id="section-toc.1-1.3.2.2.2.3">
<p id="section-toc.1-1.3.2.2.2.3.1"><a href="#section-3.2.3" class="xref">3.2.3</a>. <a href="#name-maximum-dynamic-table-capac" class="xref">Maximum Dynamic Table Capacity</a><a href="#section-toc.1-1.3.2.2.2.3.1" class="pilcrow">¶</a></p>
</li>
<li class="ulEmpty toc compact" id="section-toc.1-1.3.2.2.2.4">
<p id="section-toc.1-1.3.2.2.2.4.1"><a href="#section-3.2.4" class="xref">3.2.4</a>. <a href="#name-absolute-indexing" class="xref">Absolute Indexing</a><a href="#section-toc.1-1.3.2.2.2.4.1" class="pilcrow">¶</a></p>
</li>
<li class="ulEmpty toc compact" id="section-toc.1-1.3.2.2.2.5">