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  10 <title>mod_h2 - Apache HTTP Server Version 2.5</title>
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  20 <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>
  21 <p class="apache">Apache HTTP Server Version 2.5</p>
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  25 <a href="http://www.apache.org/">Apache</a> &gt; <a href="http://httpd.apache.org/">HTTP Server</a> &gt; <a href="http://httpd.apache.org/docs/">Documentation</a> &gt; <a href="../">Version 2.5</a> &gt; <a href="./">Modules</a></div>
  26 <div id="page-content">
  27 <div id="preamble"><h1>Apache Module mod_h2</h1>
  28 <div class="toplang">
  29 <p><span>Available Languages: </span><a href="../en/mod/mod_h2.html" title="English">&nbsp;en&nbsp;</a></p>
  30 </div>
  31 <table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Support for the HTTP/2 transport layer</td></tr>
  32 <tr><th><a href="module-dict.html#Status">Status:</a></th><td>Extension</td></tr>
  33 <tr><th><a href="module-dict.html#ModuleIdentifier">Module Identifier:</a></th><td>h2_module</td></tr>
  34 <tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>mod_h2.c</td></tr></table>
  35 <h3>Summary</h3>
  36
  37         <p>This module provides HTTP/2 (RFC 7540) support for the Apache
  38             HTTP Server.</p>
  39
  40         <p>This module relies on <a href="http://nghttp2.org/">libnghttp2</a>
  41             to provide the core http/2 engine.</p>
  42
  43     </div>
  44 <div id="quickview"><h3 class="directives">Directives</h3>
  45 <ul id="toc">
  46 <li><img alt="" src="../images/down.gif" /> <a href="#h2bufferoutput">H2BufferOutput</a></li>
  47 <li><img alt="" src="../images/down.gif" /> <a href="#h2buffersize">H2BufferSize</a></li>
  48 <li><img alt="" src="../images/down.gif" /> <a href="#h2bufferwritemax">H2BufferWriteMax</a></li>
  49 <li><img alt="" src="../images/down.gif" /> <a href="#h2direct">H2Direct</a></li>
  50 <li><img alt="" src="../images/down.gif" /> <a href="#h2maxheaderlistsize">H2MaxHeaderListSize</a></li>
  51 <li><img alt="" src="../images/down.gif" /> <a href="#h2maxsessionstreams">H2MaxSessionStreams</a></li>
  52 <li><img alt="" src="../images/down.gif" /> <a href="#h2maxworkeridleseconds">H2MaxWorkerIdleSeconds</a></li>
  53 <li><img alt="" src="../images/down.gif" /> <a href="#h2maxworkers">H2MaxWorkers</a></li>
  54 <li><img alt="" src="../images/down.gif" /> <a href="#h2minworkers">H2MinWorkers</a></li>
  55 <li><img alt="" src="../images/down.gif" /> <a href="#h2serializeheaders">H2SerializeHeaders</a></li>
  56 <li><img alt="" src="../images/down.gif" /> <a href="#h2sessionextrafiles">H2SessionExtraFiles</a></li>
  57 <li><img alt="" src="../images/down.gif" /> <a href="#h2streammaxmemsize">H2StreamMaxMemSize</a></li>
  58 <li><img alt="" src="../images/down.gif" /> <a href="#h2windowsize">H2WindowSize</a></li>
  59 </ul>
  60 <ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div>
  61
  62 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
  63 <div class="directive-section"><h2><a name="H2BufferOutput" id="H2BufferOutput">H2BufferOutput</a> <a name="h2bufferoutput" id="h2bufferoutput">Directive</a></h2>
  64 <table class="directive">
  65 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Output Buffering Switch</td></tr>
  66 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2BufferOutput on|off</code></td></tr>
  67 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
  68 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
  69 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_h2</td></tr>
  70 </table>
  71             <p>
  72                 This directive toggles if buffering of HTTP/2 output shall be used
  73                 or if data is written immediately when it arrives. Unless specified
  74                 otherwise, this directive is <code>on</code> for TLS connections and
  75                 <code>off</code> for plain connections.
  76             </p>
  77             <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2BufferOutput on</pre>
  78 </div>
  79
  80 </div>
  81 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
  82 <div class="directive-section"><h2><a name="H2BufferSize" id="H2BufferSize">H2BufferSize</a> <a name="h2buffersize" id="h2buffersize">Directive</a></h2>
  83 <table class="directive">
  84 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Buffer size for outgoing data per HTTP/2 connection.</td></tr>
  85 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2BufferSize <em>bytes</em></code></td></tr>
  86 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2BufferSize 65536</code></td></tr>
  87 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
  88 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
  89 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_h2</td></tr>
  90 </table>
  91             <p>
  92                 This directive sets the size of the buffer used to hold outgoing
  93                 HTTP/2 raw data, should <code>H2BufferOutput</code> be switched on.
  94                 This data is allocated per HTTP/2 connection, not stream and is
  95                 counted against the raw protocol data.
  96             </p>
  97             <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2BufferSize 128000</pre>
  98 </div>
  99
 100 </div>
 101 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 102 <div class="directive-section"><h2><a name="H2BufferWriteMax" id="H2BufferWriteMax">H2BufferWriteMax</a> <a name="h2bufferwritemax" id="h2bufferwritemax">Directive</a></h2>
 103 <table class="directive">
 104 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum size of write on a HTTP/2 connection.</td></tr>
 105 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2BufferWriteMax <em>bytes</em></code></td></tr>
 106 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2BufferWriteMax 16384</code></td></tr>
 107 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
 108 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
 109 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_h2</td></tr>
 110 </table>
 111             <p>
 112                 This directive sets maximum amount of data sent out in a single
 113                 write on a http/2 connection. It only takes effect when
 114                 <code>H2BufferOutput</code> is switched on.
 115             </p><p>
 116                 This directive affects performance of underlying TLS transports. TLS
 117                 transforms each write into an encrypted record. Clients need
 118                 to receive all of the record in order to decrypt it. Larger sizes
 119                 result in better server performance, shorter sizes can affect web
 120                 page paint timings.
 121             </p><p>
 122                 <code>BufferSize</code> should be a multiple of <code>H2BufferWriteMax</code>.
 123                 <code>H2BufferWriteMax</code>, if larger than 16k, should be a multiple of 16k,
 124                 since this is the TLS max record size. Be aware that there are TLS
 125                 extensions to limit the record size to powers of 2 less than 16k.
 126             </p>
 127             <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2BufferWriteMax 8000</pre>
 128 </div>
 129
 130 </div>
 131 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 132 <div class="directive-section"><h2><a name="H2Direct" id="H2Direct">H2Direct</a> <a name="h2direct" id="h2direct">Directive</a></h2>
 133 <table class="directive">
 134 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>H2 Direct Protocol Switch</td></tr>
 135 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2Direct on|off</code></td></tr>
 136 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2Direct on</code></td></tr>
 137 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
 138 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
 139 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_h2</td></tr>
 140 </table>
 141             <p>
 142                 This directive toggles the usage of the HTTP/2 Direct Mode. This
 143                 should be used inside a
 144                 <code class="directive"><a href="../mod/core.html#virtualhost">&lt;VirtualHost&gt;</a></code>
 145                 section to enable direct HTTP/2 communication for that virtual host.
 146                 Direct communication means that if the first bytes received by the
 147                 server on a connection match the HTTP/2 preamble, the HTTP/2
 148                 protocol is switched to immediately without further negotiation.
 149                 This mode falls outside the RFC 7540 but has become widely implemented
 150                 as it is very convenient for development and testing.
 151                 By default the direct HTTP/2 mode is enabled.
 152             </p>
 153             <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2Direct on</pre>
 154 </div>
 155
 156 </div>
 157 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 158 <div class="directive-section"><h2><a name="H2MaxHeaderListSize" id="H2MaxHeaderListSize">H2MaxHeaderListSize</a> <a name="h2maxheaderlistsize" id="h2maxheaderlistsize">Directive</a></h2>
 159 <table class="directive">
 160 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum size of acceptable stream headers.</td></tr>
 161 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2MaxHeaderListSize <em>bytes</em></code></td></tr>
 162 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2MaxHeaderListSize 16384</code></td></tr>
 163 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
 164 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
 165 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_h2</td></tr>
 166 </table>
 167             <p>
 168                 This directive sets the maximum amount of stream header bytes that
 169                 the server is willing to accept. It is announced to the client during
 170                 the initial HTTP/2 handshake.
 171             </p>
 172             <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2MaxHeaderListSize 10000</pre>
 173 </div>
 174
 175 </div>
 176 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 177 <div class="directive-section"><h2><a name="H2MaxSessionStreams" id="H2MaxSessionStreams">H2MaxSessionStreams</a> <a name="h2maxsessionstreams" id="h2maxsessionstreams">Directive</a></h2>
 178 <table class="directive">
 179 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum number of active streams per HTTP/2 session.</td></tr>
 180 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2MaxSessionStreams <em>n</em></code></td></tr>
 181 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2MaxSessionStreams 100</code></td></tr>
 182 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
 183 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
 184 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_h2</td></tr>
 185 </table>
 186             <p>
 187                 This directive sets the maximum number of active streams per HTTP/2 session (e.g. connection)
 188                 that the server allows. A stream is active if it is not <code>idle</code> or
 189                 <code>closed</code> according to RFC 7540.
 190             </p>
 191             <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2MaxSessionStreams 20</pre>
 192 </div>
 193
 194 </div>
 195 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 196 <div class="directive-section"><h2><a name="H2MaxWorkerIdleSeconds" id="H2MaxWorkerIdleSeconds">H2MaxWorkerIdleSeconds</a> <a name="h2maxworkeridleseconds" id="h2maxworkeridleseconds">Directive</a></h2>
 197 <table class="directive">
 198 <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>
 199 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2MaxWorkerIdleSeconds <em>n</em></code></td></tr>
 200 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2MaxWorkerIdleSeconds 600</code></td></tr>
 201 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
 202 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
 203 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_h2</td></tr>
 204 </table>
 205             <p>
 206                 This directive sets the maximum number of seconds a h2 worker may
 207                 idle until it shuts itself down. This only happens while the number of
 208                 h2 workers exceeds <code>H2MinWorkers</code>.
 209             </p>
 210             <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2MaxWorkerIdleSeconds 20</pre>
 211 </div>
 212
 213 </div>
 214 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 215 <div class="directive-section"><h2><a name="H2MaxWorkers" id="H2MaxWorkers">H2MaxWorkers</a> <a name="h2maxworkers" id="h2maxworkers">Directive</a></h2>
 216 <table class="directive">
 217 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum number of worker threads to use per child process.</td></tr>
 218 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2MaxWorkers <em>n</em></code></td></tr>
 219 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
 220 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
 221 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_h2</td></tr>
 222 </table>
 223             <p>
 224                 This directive sets the maximum number of worker threads to spawn
 225                 per child process for HTTP/2 processing. If this directive is not used,
 226                 <code>mod_h2</code> will chose a value suitable for the <code>mpm</code>
 227                 module loaded.
 228             </p>
 229             <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2MaxWorkers 20</pre>
 230 </div>
 231
 232 </div>
 233 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 234 <div class="directive-section"><h2><a name="H2MinWorkers" id="H2MinWorkers">H2MinWorkers</a> <a name="h2minworkers" id="h2minworkers">Directive</a></h2>
 235 <table class="directive">
 236 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Minimal number of worker threads to use per child process.</td></tr>
 237 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2MinWorkers <em>n</em></code></td></tr>
 238 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
 239 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
 240 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_h2</td></tr>
 241 </table>
 242             <p>
 243                 This directive sets the minimum number of worker threads to spawn
 244                 per child process for HTTP/2 processing. If this directive is not used,
 245                 <code>mod_h2</code> will chose a value suitable for the <code>mpm</code>
 246                 module loaded.
 247             </p>
 248             <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2MinWorkers 10</pre>
 249 </div>
 250
 251 </div>
 252 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 253 <div class="directive-section"><h2><a name="H2SerializeHeaders" id="H2SerializeHeaders">H2SerializeHeaders</a> <a name="h2serializeheaders" id="h2serializeheaders">Directive</a></h2>
 254 <table class="directive">
 255 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Serialize Request/Resoonse Processing Switch</td></tr>
 256 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2SerializeHeaders on|off</code></td></tr>
 257 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2SerializeHeaders off</code></td></tr>
 258 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
 259 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
 260 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_h2</td></tr>
 261 </table>
 262             <p>
 263                 This directive toggles if HTTP/2 requests shall be serialized in
 264                 HTTP/1.1 format for processing by <code>httpd</code> core or if
 265                 received binary data shall be passed into the <code>request_rec</code>s
 266                 directly.
 267             </p>
 268             <p>
 269                 Serialization will lower performance, but gives more backward
 270                 compatibility in case custom filters/hooks need it.
 271             </p>
 272             <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2SerializeHeaders on</pre>
 273 </div>
 274
 275 </div>
 276 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 277 <div class="directive-section"><h2><a name="H2SessionExtraFiles" id="H2SessionExtraFiles">H2SessionExtraFiles</a> <a name="h2sessionextrafiles" id="h2sessionextrafiles">Directive</a></h2>
 278 <table class="directive">
 279 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of Extra File Handles</td></tr>
 280 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2SessionExtraFiles <em>n</em></code></td></tr>
 281 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2SessionExtraFiles 5</code></td></tr>
 282 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
 283 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
 284 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_h2</td></tr>
 285 </table>
 286             <p>
 287                 This directive sets maximum number of <em>extra</em> file handles
 288                 a HTTP/2 session is allowed to use. A file handle is counted as
 289                 <em>extra</em> when it is transfered from a h2 worker thread to
 290                 the main HTTP/2 connection handling. This commonly happens when
 291                 serving static files.
 292             </p><p>
 293                 Depending on the processing model configured on the server, the
 294                 number of connections times number of active streams may exceed
 295                 the number of file handles for the process. On the other hand,
 296                 converting every file into memory bytes early results in too
 297                 many buffer writes. This option helps to mitigate that.
 298             </p><p>
 299                 The number of file handles used by a server process is then in
 300                 the order of:
 301             </p>
 302             <pre>(h2_connections * extra_files) + (h2_max_worker)</pre>
 303             <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2SessionExtraFiles 10</pre>
 304 </div>
 305
 306 </div>
 307 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 308 <div class="directive-section"><h2><a name="H2StreamMaxMemSize" id="H2StreamMaxMemSize">H2StreamMaxMemSize</a> <a name="h2streammaxmemsize" id="h2streammaxmemsize">Directive</a></h2>
 309 <table class="directive">
 310 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum amount of output data buffered per stream.</td></tr>
 311 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2StreamMaxMemSize <em>bytes</em></code></td></tr>
 312 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2StreamMaxMemSize 65536</code></td></tr>
 313 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
 314 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
 315 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_h2</td></tr>
 316 </table>
 317             <p>
 318                 This directive sets the maximum number of outgoing data bytes buffered in memory
 319                 for an active streams. This memory is not allocated per stream as such. Allocations
 320                 are counted against this limit when they are about to be done. Stream processing
 321                 freezes when the limit has been reached and will only continue when buffered data
 322                 has been sent out to the client.
 323             </p>
 324             <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2StreamMaxMemSize 128000</pre>
 325 </div>
 326
 327 </div>
 328 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 329 <div class="directive-section"><h2><a name="H2WindowSize" id="H2WindowSize">H2WindowSize</a> <a name="h2windowsize" id="h2windowsize">Directive</a></h2>
 330 <table class="directive">
 331 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Size of Stream Window for upstream data.</td></tr>
 332 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2WindowSize <em>bytes</em></code></td></tr>
 333 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2WindowSize 65536</code></td></tr>
 334 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
 335 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
 336 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_h2</td></tr>
 337 </table>
 338             <p>
 339                 This directive sets the size of the window that is used for flow control
 340                 from client to server and limits the amount of data the server has to buffer.
 341                 The client will stop sending on a stream once the limit has been reached until
 342                 the server announces more available space (as it has processed some of the data).
 343             </p><p>
 344                 This limit affects only request bodies, not its meta data such as headers. Also,
 345                 it has no effect on response bodies as the window size for those are managed
 346                 by the clients.
 347             </p>
 348             <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2WindowSize 128000</pre>
 349 </div>
 350
 351 </div>
 352 </div>
 353 <div class="bottomlang">
 354 <p><span>Available Languages: </span><a href="../en/mod/mod_h2.html" title="English">&nbsp;en&nbsp;</a></p>
 355 </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&amp;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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