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556 lines
35 KiB
XML
<?xml version="1.0" encoding="ISO-8859-1"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head>
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<meta content="text/html; charset=ISO-8859-1" http-equiv="Content-Type" />
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<!--
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This file is generated from xml source: DO NOT EDIT
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XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
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-->
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<title>mod_http2 - Apache HTTP Server Version 2.5</title>
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<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" />
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<link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" />
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<link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /><link rel="stylesheet" type="text/css" href="../style/css/prettify.css" />
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<script src="../style/scripts/prettify.min.js" type="text/javascript">
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</script>
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||
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||
<link href="../images/favicon.ico" rel="shortcut icon" /></head>
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<body>
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||
<div id="page-header">
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<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/quickreference.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p>
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<p class="apache">Apache HTTP Server Version 2.5</p>
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<img alt="" src="../images/feather.gif" /></div>
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<div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div>
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<div id="path">
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<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="../">Version 2.5</a> > <a href="./">Modules</a></div>
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<div id="page-content">
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<div id="preamble"><h1>Apache Module mod_http2</h1>
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<div class="toplang">
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<p><span>Available Languages: </span><a href="../en/mod/mod_http2.html" title="English"> en </a></p>
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</div>
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<table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Support for the HTTP/2 transport layer</td></tr>
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<tr><th><a href="module-dict.html#Status">Status:</a></th><td>Extension</td></tr>
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<tr><th><a href="module-dict.html#ModuleIdentifier">Module<EFBFBD>Identifier:</a></th><td>http2_module</td></tr>
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<tr><th><a href="module-dict.html#SourceFile">Source<EFBFBD>File:</a></th><td>mod_http2.c</td></tr>
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<tr><th><a href="module-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.4.17 and later</td></tr></table>
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<h3>Summary</h3>
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<p>This module provides HTTP/2 (RFC 7540) support for the Apache
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HTTP Server.</p>
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<p>This module relies on <a href="http://nghttp2.org/">libnghttp2</a>
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to provide the core http/2 engine.</p>
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<div class="warning"><h3>Warning</h3>
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<p>This module is experimental. Its behaviors, directives, and
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defaults are subject to more change from release to
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release relative to other standard modules. Users are encouraged to
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consult the "CHANGES" file for potential updates.</p>
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</div>
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<p>You must enable HTTP/2 via <code class="directive"><a href="../mod/core.html#protocols">Protocols</a></code> in order to use the
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functionality described in this document:</p>
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<pre class="prettyprint lang-config">Protocols h2 http/1.1</pre>
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</div>
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<div id="quickview"><h3 class="directives">Directives</h3>
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<ul id="toc">
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<li><img alt="" src="../images/down.gif" /> <a href="#h2direct">H2Direct</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#h2maxsessionstreams">H2MaxSessionStreams</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#h2maxworkeridleseconds">H2MaxWorkerIdleSeconds</a></li>
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||
<li><img alt="" src="../images/down.gif" /> <a href="#h2maxworkers">H2MaxWorkers</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#h2minworkers">H2MinWorkers</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#h2moderntlsonly">H2ModernTLSOnly</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#h2push">H2Push</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#h2serializeheaders">H2SerializeHeaders</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#h2sessionextrafiles">H2SessionExtraFiles</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#h2streammaxmemsize">H2StreamMaxMemSize</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#h2tlscooldownsecs">H2TLSCoolDownSecs</a></li>
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||
<li><img alt="" src="../images/down.gif" /> <a href="#h2tlswarmupsize">H2TLSWarmUpSize</a></li>
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||
<li><img alt="" src="../images/down.gif" /> <a href="#h2upgrade">H2Upgrade</a></li>
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||
<li><img alt="" src="../images/down.gif" /> <a href="#h2windowsize">H2WindowSize</a></li>
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||
</ul>
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<ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div>
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<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
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<div class="directive-section"><h2><a name="H2Direct" id="H2Direct">H2Direct</a> <a name="h2direct" id="h2direct">Directive</a></h2>
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<table class="directive">
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<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>H2 Direct Protocol Switch</td></tr>
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<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2Direct on|off</code></td></tr>
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<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2Direct on for h2c, off for h2 protocol</code></td></tr>
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<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
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<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
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<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_http2</td></tr>
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</table>
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<p>
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This directive toggles the usage of the HTTP/2 Direct Mode. This
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should be used inside a
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<code class="directive"><a href="../mod/core.html#virtualhost"><VirtualHost></a></code>
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section to enable direct HTTP/2 communication for that virtual host.
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</p>
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<p>
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Direct communication means that if the first bytes received by the
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server on a connection match the HTTP/2 preamble, the HTTP/2
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protocol is switched to immediately without further negotiation.
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This mode is defined in RFC 7540 for the cleartext (h2c) case. Its
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use on TLS connections not mandated by the standard.
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</p>
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<p>
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When a server/vhost does not have h2 or h2c enabled via
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<code class="directive"><a href="../mod/core.html#protocols"><Protocols></a></code>,
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the connection is never inspected for a HTTP/2 preamble. H2Direct
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does not matter then. This is important for connections that
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use protocols where an initial read might hang indefinitely, such
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as NNTP.
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</p>
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<p>
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For clients that have out-of-band knowledge about a server
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supporting h2c, direct HTTP/2 saves the client from having to
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perform an HTTP/1.1 upgrade, resulting in better performance
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and avoiding the Upgrade restrictions on request bodies.
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</p>
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<p>
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This makes direct h2c attractive for server to server communication
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as well, when the connection can be trusted or is secured by other means.
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</p>
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<div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2Direct on</pre>
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</div>
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</div>
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<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
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<div class="directive-section"><h2><a name="H2MaxSessionStreams" id="H2MaxSessionStreams">H2MaxSessionStreams</a> <a name="h2maxsessionstreams" id="h2maxsessionstreams">Directive</a></h2>
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<table class="directive">
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<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum number of active streams per HTTP/2 session.</td></tr>
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<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2MaxSessionStreams <em>n</em></code></td></tr>
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<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2MaxSessionStreams 100</code></td></tr>
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<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
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<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
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<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_http2</td></tr>
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||
</table>
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<p>
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This directive sets the maximum number of active streams per HTTP/2 session (e.g. connection)
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that the server allows. A stream is active if it is not <code>idle</code> or
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<code>closed</code> according to RFC 7540.
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</p>
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<div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2MaxSessionStreams 20</pre>
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</div>
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</div>
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<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
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<div class="directive-section"><h2><a name="H2MaxWorkerIdleSeconds" id="H2MaxWorkerIdleSeconds">H2MaxWorkerIdleSeconds</a> <a name="h2maxworkeridleseconds" id="h2maxworkeridleseconds">Directive</a></h2>
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<table class="directive">
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||
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum number of seconds h2 workers remain idle until shut down.</td></tr>
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<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2MaxWorkerIdleSeconds <em>n</em></code></td></tr>
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<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2MaxWorkerIdleSeconds 600</code></td></tr>
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<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
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||
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
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<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_http2</td></tr>
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||
</table>
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<p>
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This directive sets the maximum number of seconds a h2 worker may
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idle until it shuts itself down. This only happens while the number of
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h2 workers exceeds <code>H2MinWorkers</code>.
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||
</p>
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||
<div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2MaxWorkerIdleSeconds 20</pre>
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||
</div>
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||
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||
</div>
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||
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
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||
<div class="directive-section"><h2><a name="H2MaxWorkers" id="H2MaxWorkers">H2MaxWorkers</a> <a name="h2maxworkers" id="h2maxworkers">Directive</a></h2>
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||
<table class="directive">
|
||
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum number of worker threads to use per child process.</td></tr>
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||
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2MaxWorkers <em>n</em></code></td></tr>
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||
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
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||
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
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||
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_http2</td></tr>
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||
</table>
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||
<p>
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This directive sets the maximum number of worker threads to spawn
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||
per child process for HTTP/2 processing. If this directive is not used,
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||
<code>mod_http2</code> will chose a value suitable for the <code>mpm</code>
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||
module loaded.
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||
</p>
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||
<div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2MaxWorkers 20</pre>
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||
</div>
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||
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||
</div>
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<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
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||
<div class="directive-section"><h2><a name="H2MinWorkers" id="H2MinWorkers">H2MinWorkers</a> <a name="h2minworkers" id="h2minworkers">Directive</a></h2>
|
||
<table class="directive">
|
||
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Minimal number of worker threads to use per child process.</td></tr>
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||
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2MinWorkers <em>n</em></code></td></tr>
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||
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
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||
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
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||
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_http2</td></tr>
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||
</table>
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<p>
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This directive sets the minimum number of worker threads to spawn
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per child process for HTTP/2 processing. If this directive is not used,
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<code>mod_http2</code> will chose a value suitable for the <code>mpm</code>
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||
module loaded.
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</p>
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<div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2MinWorkers 10</pre>
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</div>
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</div>
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<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
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<div class="directive-section"><h2><a name="H2ModernTLSOnly" id="H2ModernTLSOnly">H2ModernTLSOnly</a> <a name="h2moderntlsonly" id="h2moderntlsonly">Directive</a></h2>
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<table class="directive">
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||
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Require HTTP/2 connections to be "modern TLS" only</td></tr>
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||
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2ModernTLSOnly on|off</code></td></tr>
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<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2ModernTLSOnly on</code></td></tr>
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||
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
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||
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
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||
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_http2</td></tr>
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||
</table>
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||
<p>
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This directive toggles the security checks on HTTP/2 connections
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in TLS mode (https:). This can be used server wide or for specific
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<code class="directive"><a href="../mod/core.html#virtualhost"><VirtualHost></a></code>s.
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||
</p>
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||
<p>
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The security checks require that the TSL protocol is at least
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TLSv1.2 and that none of the ciphers listed in RFC 7540, Appendix A
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is used. These checks will be extended once new security requirements
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||
come into place.
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||
</p>
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<p>
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The name stems from the
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<a href="https://wiki.mozilla.org/Security/Server_Side_TLS">Security/Server Side TLS</a>
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definitions at mozilla where "modern compatibility" is defined. Mozilla Firefox and
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||
other browsers require modern compatibility for HTTP/2 connections. As everything
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||
in OpSec, this is a moving target and can be expected to evolve in the future.
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</p>
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<p>
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One purpose of having these checks in mod_http2 is to enforce this
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security level for all connections, not only those from browsers. The other
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||
purpose is to prevent the negotiation of HTTP/2 as a protocol should
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the requirements not be met.
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||
</p>
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||
<p>
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Ultimately, the security of the TLS connection is determined by the
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||
server configuration directives for mod_ssl.
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||
</p>
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||
<div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2ModernTLSOnly off</pre>
|
||
</div>
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||
|
||
</div>
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||
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
|
||
<div class="directive-section"><h2><a name="H2Push" id="H2Push">H2Push</a> <a name="h2push" id="h2push">Directive</a></h2>
|
||
<table class="directive">
|
||
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>H2 Server Push Switch</td></tr>
|
||
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2Push on|off</code></td></tr>
|
||
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2Push on</code></td></tr>
|
||
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
|
||
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
|
||
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_http2</td></tr>
|
||
</table>
|
||
<p>
|
||
This directive toggles the usage of the HTTP/2 server push
|
||
protocol feature. This should be used inside a
|
||
<code class="directive"><a href="../mod/core.html#virtualhost"><VirtualHost></a></code>
|
||
section to enable direct HTTP/2 communication for that virtual host.
|
||
</p>
|
||
<p>
|
||
The HTTP/2 protocol allows the server to push other resources to
|
||
a client when it asked for a particular one. This is helpful
|
||
if those resources are connected in some way and the client can
|
||
be expected to ask for it anyway. The pushing then saves the
|
||
time it takes the client to ask for the resources itself. On the
|
||
other hand, pushing resources the client never needs or already
|
||
has is a waste of bandwidth.
|
||
</p>
|
||
<p>
|
||
Server pushes are detected by inspecting the <code>Link</code> headers of
|
||
responses (see https://tools.ietf.org/html/rfc5988 for the
|
||
specification). When a link thus specified has the <code>rel=preload</code>
|
||
attribute, it is treated as a resource to be pushed.
|
||
</p>
|
||
<p>
|
||
Link headers in responses are either set by the application or
|
||
can be configured via <code class="module"><a href="../mod/mod_headers.html">mod_headers</a></code> as:
|
||
</p>
|
||
<div class="example"><h3>mod_headers example</h3><pre class="prettyprint lang-config"><Location /index.html>
|
||
Header add Link "</css/site.css>;rel=preload"
|
||
Header add Link "</images/logo.jpg>;rel=preload"
|
||
</Location></pre>
|
||
</div>
|
||
<p>
|
||
As the example shows, there can be several link headers added
|
||
to a response, resulting in several pushes being triggered. There
|
||
are no checks in the module to avoid pushing the same resource
|
||
twice or more to one client. Use with care.
|
||
</p>
|
||
<p>
|
||
HTTP/2 server pushes are enabled by default. This directive
|
||
allows it to be switch off on all resources of this server/virtual
|
||
host.
|
||
</p>
|
||
<div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2Push off</pre>
|
||
</div>
|
||
<p>
|
||
Last but not least, pushes happen only when the client signals
|
||
its willingness to accept those. Most browsers do, some, like Safari 9,
|
||
do not.
|
||
</p>
|
||
|
||
</div>
|
||
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
|
||
<div class="directive-section"><h2><a name="H2SerializeHeaders" id="H2SerializeHeaders">H2SerializeHeaders</a> <a name="h2serializeheaders" id="h2serializeheaders">Directive</a></h2>
|
||
<table class="directive">
|
||
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Serialize Request/Response Processing Switch</td></tr>
|
||
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2SerializeHeaders on|off</code></td></tr>
|
||
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2SerializeHeaders off</code></td></tr>
|
||
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
|
||
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
|
||
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_http2</td></tr>
|
||
</table>
|
||
<p>
|
||
This directive toggles if HTTP/2 requests shall be serialized in
|
||
HTTP/1.1 format for processing by <code>httpd</code> core or if
|
||
received binary data shall be passed into the <code>request_rec</code>s
|
||
directly.
|
||
</p>
|
||
<p>
|
||
Serialization will lower performance, but gives more backward
|
||
compatibility in case custom filters/hooks need it.
|
||
</p>
|
||
<div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2SerializeHeaders on</pre>
|
||
</div>
|
||
|
||
</div>
|
||
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
|
||
<div class="directive-section"><h2><a name="H2SessionExtraFiles" id="H2SessionExtraFiles">H2SessionExtraFiles</a> <a name="h2sessionextrafiles" id="h2sessionextrafiles">Directive</a></h2>
|
||
<table class="directive">
|
||
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of Extra File Handles</td></tr>
|
||
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2SessionExtraFiles <em>n</em></code></td></tr>
|
||
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2SessionExtraFiles 5</code></td></tr>
|
||
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
|
||
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
|
||
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_http2</td></tr>
|
||
</table>
|
||
<p>
|
||
This directive sets maximum number of <em>extra</em> file handles
|
||
a HTTP/2 session is allowed to use. A file handle is counted as
|
||
<em>extra</em> when it is transferred from a h2 worker thread to
|
||
the main HTTP/2 connection handling. This commonly happens when
|
||
serving static files.
|
||
</p><p>
|
||
Depending on the processing model configured on the server, the
|
||
number of connections times number of active streams may exceed
|
||
the number of file handles for the process. On the other hand,
|
||
converting every file into memory bytes early results in too
|
||
many buffer writes. This option helps to mitigate that.
|
||
</p><p>
|
||
The number of file handles used by a server process is then in
|
||
the order of:
|
||
</p>
|
||
<pre>(h2_connections * extra_files) + (h2_max_worker)</pre>
|
||
<div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2SessionExtraFiles 10</pre>
|
||
</div>
|
||
|
||
</div>
|
||
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
|
||
<div class="directive-section"><h2><a name="H2StreamMaxMemSize" id="H2StreamMaxMemSize">H2StreamMaxMemSize</a> <a name="h2streammaxmemsize" id="h2streammaxmemsize">Directive</a></h2>
|
||
<table class="directive">
|
||
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum amount of output data buffered per stream.</td></tr>
|
||
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2StreamMaxMemSize <em>bytes</em></code></td></tr>
|
||
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2StreamMaxMemSize 65536</code></td></tr>
|
||
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
|
||
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
|
||
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_http2</td></tr>
|
||
</table>
|
||
<p>
|
||
This directive sets the maximum number of outgoing data bytes buffered in memory
|
||
for an active streams. This memory is not allocated per stream as such. Allocations
|
||
are counted against this limit when they are about to be done. Stream processing
|
||
freezes when the limit has been reached and will only continue when buffered data
|
||
has been sent out to the client.
|
||
</p>
|
||
<div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2StreamMaxMemSize 128000</pre>
|
||
</div>
|
||
|
||
</div>
|
||
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
|
||
<div class="directive-section"><h2><a name="H2TLSCoolDownSecs" id="H2TLSCoolDownSecs">H2TLSCoolDownSecs</a> <a name="h2tlscooldownsecs" id="h2tlscooldownsecs">Directive</a></h2>
|
||
<table class="directive">
|
||
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td /></tr>
|
||
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2TLSCoolDownSecs seconds</code></td></tr>
|
||
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2TLSCoolDownSecs 1</code></td></tr>
|
||
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
|
||
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
|
||
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_http2</td></tr>
|
||
</table>
|
||
<p>
|
||
This directive sets the number of seconds of idle time on a TLS
|
||
connection before the TLS write size falls back to small (~1300 bytes)
|
||
length.
|
||
This can be used server wide or for specific
|
||
<code class="directive"><a href="../mod/core.html#virtualhost"><VirtualHost></a></code>s.
|
||
</p>
|
||
<p>
|
||
See <code class="directive"><H2TLSWarmUpSize></code> for a
|
||
description of TLS warmup. H2TLSCoolDownSecs reflects the fact
|
||
that connections may deteriorate over time (and TCP flow adjusts)
|
||
for idle connections as well. It is beneficial to overall performance
|
||
to fall back to the pre-warmup phase after a number of seconds that
|
||
no data has been sent.
|
||
</p>
|
||
<p>
|
||
In deployments where connections can be considered reliable, this
|
||
timer can be disabled by setting it to 0.
|
||
</p>
|
||
<p>
|
||
The following example sets the seconds to zero, effectively disabling
|
||
any cool down. Warmed up TLS connections stay on maximum record
|
||
size.
|
||
</p>
|
||
<div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2TLSCoolDownSecs 0</pre>
|
||
</div>
|
||
|
||
</div>
|
||
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
|
||
<div class="directive-section"><h2><a name="H2TLSWarmUpSize" id="H2TLSWarmUpSize">H2TLSWarmUpSize</a> <a name="h2tlswarmupsize" id="h2tlswarmupsize">Directive</a></h2>
|
||
<table class="directive">
|
||
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td /></tr>
|
||
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2TLSWarmUpSize amount</code></td></tr>
|
||
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2TLSWarmUpSize 1048576</code></td></tr>
|
||
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
|
||
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
|
||
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_http2</td></tr>
|
||
</table>
|
||
<p>
|
||
This directive sets the number of bytes to be sent in small
|
||
TLS records (~1300 bytes) until doing maximum sized writes (16k)
|
||
on https: HTTP/2 connections.
|
||
This can be used server wide or for specific
|
||
<code class="directive"><a href="../mod/core.html#virtualhost"><VirtualHost></a></code>s.
|
||
</p>
|
||
<p>
|
||
Measurements by <a href="https://www.igvita.com">google performance
|
||
labs</a> show that best performance on TLS connections is reached,
|
||
if initial record sizes stay below the MTU level, to allow a
|
||
complete record to fit into an IP packet.
|
||
</p>
|
||
<p>
|
||
While TCP adjust its flow-control and window sizes, longer TLS
|
||
records can get stuck in queues or get lost and need retransmission.
|
||
This is of course true for all packets. TLS however needs the
|
||
whole record in order to decrypt it. Any missing bytes at the end
|
||
will stall usage of the received ones.
|
||
</p>
|
||
<p>
|
||
After a sufficient number of bytes have been send successfully,
|
||
the TCP state of the connection is stable and maximum TLS record
|
||
sizes (16 KB) can be used for optimal performance.
|
||
</p>
|
||
<p>
|
||
In deployments where servers are reached locally or over reliable
|
||
connections only, the value might be decreased with 0 disabling
|
||
any warmup phase altogether.
|
||
</p>
|
||
<p>
|
||
The following example sets the size to zero, effectively disabling
|
||
any warmup phase.
|
||
</p>
|
||
<div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2TLSWarmUpSize 0</pre>
|
||
</div>
|
||
|
||
</div>
|
||
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
|
||
<div class="directive-section"><h2><a name="H2Upgrade" id="H2Upgrade">H2Upgrade</a> <a name="h2upgrade" id="h2upgrade">Directive</a></h2>
|
||
<table class="directive">
|
||
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>H2 Upgrade Protocol Switch</td></tr>
|
||
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2Upgrade on|off</code></td></tr>
|
||
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2Upgrade on for h2c, off for h2 protocol</code></td></tr>
|
||
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
|
||
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
|
||
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_http2</td></tr>
|
||
</table>
|
||
<p>
|
||
This directive toggles the usage of the HTTP/1.1 Upgrade method
|
||
for switching to HTTP/2. This
|
||
should be used inside a
|
||
<code class="directive"><a href="../mod/core.html#virtualhost"><VirtualHost></a></code>
|
||
section to enable Upgrades to HTTP/2 for that virtual host.
|
||
</p>
|
||
<p>
|
||
This method of switching protocols is defined in HTTP/1.1 and
|
||
uses the "Upgrade" header (thus the name) to announce willingness
|
||
to use another protocol. This may happen on any request of a
|
||
HTTP/1.1 connection.
|
||
</p>
|
||
<p>
|
||
This method of protocol switching is enabled by default on cleartext
|
||
(potential h2c) connections and disabled on TLS (potential h2),
|
||
as mandated by RFC 7540.
|
||
</p>
|
||
<p>
|
||
Please be aware that Upgrades are only accepted for requests
|
||
that carry no body. POSTs and PUTs with content will never
|
||
trigger an upgrade to HTTP/2.
|
||
See <code class="directive"><H2Direct></code> for an
|
||
alternative to Upgrade.
|
||
</p>
|
||
<p>
|
||
This mode only has an effect when h2 or h2c is enabled via
|
||
the <code class="directive"><a href="../mod/core.html#protocols"><Protocols></a></code>.
|
||
</p>
|
||
<div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2Upgrade on</pre>
|
||
</div>
|
||
|
||
</div>
|
||
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
|
||
<div class="directive-section"><h2><a name="H2WindowSize" id="H2WindowSize">H2WindowSize</a> <a name="h2windowsize" id="h2windowsize">Directive</a></h2>
|
||
<table class="directive">
|
||
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Size of Stream Window for upstream data.</td></tr>
|
||
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2WindowSize <em>bytes</em></code></td></tr>
|
||
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2WindowSize 65536</code></td></tr>
|
||
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
|
||
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
|
||
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_http2</td></tr>
|
||
</table>
|
||
<p>
|
||
This directive sets the size of the window that is used for flow control
|
||
from client to server and limits the amount of data the server has to buffer.
|
||
The client will stop sending on a stream once the limit has been reached until
|
||
the server announces more available space (as it has processed some of the data).
|
||
</p><p>
|
||
This limit affects only request bodies, not its meta data such as headers. Also,
|
||
it has no effect on response bodies as the window size for those are managed
|
||
by the clients.
|
||
</p>
|
||
<div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2WindowSize 128000</pre>
|
||
</div>
|
||
|
||
</div>
|
||
</div>
|
||
<div class="bottomlang">
|
||
<p><span>Available Languages: </span><a href="../en/mod/mod_http2.html" title="English"> en </a></p>
|
||
</div><div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed again by our moderators if they are either implemented or considered invalid/off-topic. Questions on how to manage the Apache HTTP Server should be directed at either our IRC channel, #httpd, on Freenode, or sent to our <a href="http://httpd.apache.org/lists.html">mailing lists</a>.</div>
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