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Diffstat (limited to 'docs/manual/mod/mod_http2.html.en')
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1 files changed, 162 insertions, 130 deletions
diff --git a/docs/manual/mod/mod_http2.html.en b/docs/manual/mod/mod_http2.html.en index 246a1b6e..c8dde1d2 100644 --- a/docs/manual/mod/mod_http2.html.en +++ b/docs/manual/mod/mod_http2.html.en @@ -35,33 +35,54 @@ <tr><th><a href="module-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.4.17 and later</td></tr></table> <h3>Summary</h3> - <p>This module provides HTTP/2 (RFC 7540) support for the Apache - HTTP Server.</p> + <p>This module provides HTTP/2 (<a href="https://tools.ietf.org/html/rfc7540">RFC 7540</a>) + support for the Apache HTTP Server.</p> <p>This module relies on <a href="http://nghttp2.org/">libnghttp2</a> - to provide the core http/2 engine.</p> + to provide the core http/2 engine.</p> <div class="warning"><h3>Warning</h3> - <p>This module is experimental. Its behaviors, directives, and - defaults are subject to more change from release to - release relative to other standard modules. Users are encouraged to - consult the "CHANGES" file for potential updates.</p> + <p>This module is experimental. Its behaviors, directives, and + defaults are subject to more change from release to + release relative to other standard modules. Users are encouraged to + consult the "CHANGES" file for potential updates.</p> </div> + + <p>You must enable HTTP/2 via <code class="directive"><a href="../mod/core.html#protocols">Protocols</a></code> + in order to use the functionality described in this document. The + HTTP/2 protocol <a href="https://http2.github.io/faq/#does-http2-require-encryption">does not require</a> the use of encryption so two schemes are available: + <code>h2</code> (HTTP/2 over TLS) and <code>h2c</code> (HTTP/2 over TCP).</p> - <p>You must enable HTTP/2 via <code class="directive"><a href="../mod/core.html#protocols">Protocols</a></code> in order to use the - functionality described in this document:</p> - + <p>Two useful configuration schemes are:</p> + + <div class="note"><h3>HTTP/2 in a VirtualHost context (TLS only)</h3> <pre class="prettyprint lang-config">Protocols h2 http/1.1</pre> + <p>Allows HTTP/2 negotiation (h2) via TLS ALPN in a secure + <code class="directive"><a href="../mod/core.html#virtualhost"><VirtualHost></a></code>. + HTTP/2 preamble checking (Direct mode, see <code class="directive"><a href="#h2direct">H2Direct</a></code>) is disabled by default for <code>h2</code>.</p> + </div> + + <div class="note"><h3>HTTP/2 in a Server context (TLS and cleartext)</h3> + <pre class="prettyprint lang-config">Protocols h2 h2c http/1.1</pre> + <p>Allows HTTP/2 negotiation (h2) via TLS ALPN for secure + <code class="directive"><a href="../mod/core.html#virtualhost"><VirtualHost></a></code>. Allows + HTTP/2 cleartext negotiation (h2c) upgrading from an initial HTTP/1.1 + connection or via HTTP/2 preamble checking (Direct mode, see + <code class="directive"><a href="#h2direct">H2Direct</a></code>).</p> + </div> + + <p>Refer to the official <a href="https://http2.github.io/faq">HTTP/2 FAQ</a> + for any doubt about the protocol.</p> + </div> <div id="quickview"><h3>Topics</h3> <ul id="topics"> -<li><img alt="" src="../images/down.gif" /> <a href="#envvars">Environment Variables</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#how-it-works">How it works</a></li> </ul><h3 class="directives">Directives</h3> <ul id="toc"> <li><img alt="" src="../images/down.gif" /> <a href="#h2direct">H2Direct</a></li> -<li><img alt="" src="../images/down.gif" /> <a href="#h2keepalivetimeout">H2KeepAliveTimeout</a></li> <li><img alt="" src="../images/down.gif" /> <a href="#h2maxsessionstreams">H2MaxSessionStreams</a></li> <li><img alt="" src="../images/down.gif" /> <a href="#h2maxworkeridleseconds">H2MaxWorkerIdleSeconds</a></li> <li><img alt="" src="../images/down.gif" /> <a href="#h2maxworkers">H2MaxWorkers</a></li> @@ -73,19 +94,117 @@ <li><img alt="" src="../images/down.gif" /> <a href="#h2serializeheaders">H2SerializeHeaders</a></li> <li><img alt="" src="../images/down.gif" /> <a href="#h2sessionextrafiles">H2SessionExtraFiles</a></li> <li><img alt="" src="../images/down.gif" /> <a href="#h2streammaxmemsize">H2StreamMaxMemSize</a></li> -<li><img alt="" src="../images/down.gif" /> <a href="#h2streamtimeout">H2StreamTimeout</a></li> -<li><img alt="" src="../images/down.gif" /> <a href="#h2timeout">H2Timeout</a></li> <li><img alt="" src="../images/down.gif" /> <a href="#h2tlscooldownsecs">H2TLSCoolDownSecs</a></li> <li><img alt="" src="../images/down.gif" /> <a href="#h2tlswarmupsize">H2TLSWarmUpSize</a></li> <li><img alt="" src="../images/down.gif" /> <a href="#h2upgrade">H2Upgrade</a></li> <li><img alt="" src="../images/down.gif" /> <a href="#h2windowsize">H2WindowSize</a></li> </ul> -<ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div> +<h3>Bugfix checklist</h3><ul class="seealso"><li><a href="https://www.apache.org/dist/httpd/CHANGES_2.4">httpd changelog</a></li><li><a href="https://bz.apache.org/bugzilla/buglist.cgi?bug_status=__open__&list_id=144532&product=Apache%20httpd-2&query_format=specific&order=changeddate%20DESC%2Cpriority%2Cbug_severity&component=mod_http2">Known issues</a></li><li><a href="https://bz.apache.org/bugzilla/enter_bug.cgi?product=Apache%20httpd-2&component=mod_http2">Report a bug</a></li></ul><h3>See also</h3> +<ul class="seealso"> +<li><a href="#comments_section">Comments</a></li></ul></div> <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> <div class="section"> -<h2><a name="envvars" id="envvars">Environment Variables</a></h2> - - <p>This module can be configured to provide HTTP/2 related information +<h2><a name="how-it-works" id="how-it-works">How it works</a></h2> + + <h3><a name="dimensioning" id="dimensioning">HTTP/2 Dimensioning</a></h3> + <p> + Enabling HTTP/2 on your Apache Server has impact on the resource + consumption and if you have a busy site, you may need to consider + carefully the implications. + </p> + <p> + The first noticeable thing after enabling HTTP/2 is that your server + processes will start additional threads. The reason for this is that + HTTP/2 gives all requests that it receives to its own <em>Worker</em> + threads for processing, collects the results and streams them out + to the client. + </p> + <p> + In the current implementation, these workers use a separate thread + pool from the MPM workers that you might be familiar with. This is + just how things are right now and not intended to be like this forever. + (It might be forever for the 2.4.x release line, though.) So, HTTP/2 + workers, or shorter H2Workers, will not show up in <code class="module"><a href="../mod/mod_status.html">mod_status</a></code>. They + are also not counted against directives such as <code class="directive"><a href="../mod/mpm_common.html#threadsperchild">ThreadsPerChild</a></code>. However + they take <code class="directive"><a href="../mod/mpm_common.html#threadsperchild">ThreadsPerChild</a></code> + as default if you have not configured something + else via <code class="directive"><a href="#h2minworkers">H2MinWorkers</a></code> and + <code class="directive"><a href="#h2maxworkers">H2MaxWorkers</a></code>. + </p> + <p> + Another thing to watch out for is is memory consumption. Since HTTP/2 + keeps more state on the server to manage all the open request, priorities + for and dependencies between them, it will always need more memory + than HTTP/1.1 processing. There are three directives which steer the + memory footprint of a HTTP/2 connection: + <code class="directive"><a href="#h2maxsessionstreams">H2MaxSessionStreams</a></code>, + <code class="directive"><a href="#h2windowsize">H2WindowSize</a></code> and + <code class="directive"><a href="#h2streammaxmemsize">H2StreamMaxMemSize</a></code>. + </p> + <p> + <code class="directive"><a href="#h2maxsessionstreams">H2MaxSessionStreams</a></code> limits the + number of parallel requests that a client can make on a HTTP/2 connection. + It depends on your site how many you should allow. The default is 100 which + is plenty and unless you run into memory problems, I would keep it this + way. Most requests that browsers send are GETs without a body, so they + use up only a little bit of memory until the actual processing starts. + </p> + <p> + <code class="directive"><a href="#h2windowsize">H2WindowSize</a></code> controls how much + the client is allowed to send as body of a request, before it waits + for the server to encourage more. Or, the other way around, it is the + amount of request body data the server needs to be able to buffer. This + is per request. + </p> + <p> + And last, but not least, <code class="directive"><a href="#h2streammaxmemsize">H2StreamMaxMemSize</a></code> + controls how much response data shall be buffered. The request sits in + a H2Worker thread and is producing data, the HTTP/2 connection tries + to send this to the client. If the client does not read fast enough, + the connection will buffer this amount of data and then suspend the + H2Worker. + </p> + <p> + If you serve a lot of static files, <code class="directive"><a href="#h2sessionextrafiles">H2SessionExtraFiles</a></code> + is of interest. This tells the server how many file handles per + HTTP/2 connection it is allowed to waste for better performance. Because + when a request produces a static file as the response, the file handle + gets passed around and is buffered and not the file contents. That allows + to serve many large files without wasting memory or copying data + unnecessarily. However file handles are a limited resource for a process, + and if too many are used this way, requests may fail under load as + the amount of open handles has been exceeded. + </p> + + + <h3><a name="misdirected" id="misdirected">Multiple Hosts and Misdirected Requests</a></h3> + <p> + Many sites use the same TLS certificate for multiple virtual hosts. The + certificate either has a wildcard name, such as '*.example.org' or carries + several alternate names. Browsers using HTTP/2 will recognize that and reuse + an already opened connection for such hosts. + </p> + <p> + While this is great for performance, it comes at a price: such vhosts + need more care in their configuration. The problem is that you will have + multiple requests for multiple hosts on the same TLS connection. And that + makes renegotiation impossible, in face the HTTP/2 standard forbids it. + </p> + <p> + So, if you have several virtual hosts using the same certificate and + want to use HTTP/2 for them, you need to make sure that all vhosts have + exactly the same SSL configuration. You need the same protocol, + ciphers and settings for client verification. + </p> + <p> + If you mix things, Apache httpd will detect it and return a special + response code, 421 Misdirected Request, to the client. + </p> + + + <h3><a name="envvars" id="envvars">Environment Variables</a></h3> + <p> + This module can be configured to provide HTTP/2 related information as additional environment variables to the SSI and CGI namespace, as well as in custom log configurations (see <code>%{VAR_NAME}e</code>). </p> @@ -105,7 +224,8 @@ <tr><td><code>H2_STREAM_ID</code></td><td>number</td><td>HTTP/2 stream number of this request.</td></tr> <tr><td><code>H2_STREAM_TAG</code></td><td>string</td><td>HTTP/2 process unique stream identifier, consisting of connection id and stream id separated by <code>-</code>.</td></tr> </table> - + + </div> <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> <div class="directive-section"><h2><a name="H2Direct" id="H2Direct">H2Direct</a> <a name="h2direct" id="h2direct">Directive</a></h2> @@ -132,8 +252,9 @@ </p> <p> When a server/vhost does not have h2 or h2c enabled via - <code class="directive"><a href="../mod/core.html#protocols"><Protocols></a></code>, - the connection is never inspected for a HTTP/2 preamble. H2Direct + <code class="directive"><a href="../mod/core.html#protocols">Protocols</a></code>, + the connection is never inspected for a HTTP/2 preamble. + <code class="directive">H2Direct</code> does not matter then. This is important for connections that use protocols where an initial read might hang indefinitely, such as NNTP. @@ -153,34 +274,6 @@ </div> <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> -<div class="directive-section"><h2><a name="H2KeepAliveTimeout" id="H2KeepAliveTimeout">H2KeepAliveTimeout</a> <a name="h2keepalivetimeout" id="h2keepalivetimeout">Directive</a></h2> -<table class="directive"> -<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Timeout (in seconds) for idle HTTP/2 connections</td></tr> -<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2KeepAliveTimeout seconds</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> -<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.4.19 and later.</td></tr> -</table> - <p> - This directive sets the timeout for read/write operations on - idle connections where HTTP/2 is negotiated. This can be used server wide or for specific - <code class="directive"><a href="../mod/core.html#virtualhost"><VirtualHost></a></code>s. - </p> - <p> - This directive is similar to the - <code class="directive"><a href="../mod/core.html#keepalivetimeout"><KeepAliveTimeout></a></code>, but - applies only to HTTP/2 connections. A HTTP/2 connection is considered - idle when no streams are open, e.g. no requests are ongoing. - </p> - <p> - By default, for non-async MPMs (prefork, worker) the keepalive timeout - will be the same as H2Timeout. For async MPMs, the keepalive handling for - HTTP/1 connections applies as no special action is taken. - </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="H2MaxSessionStreams" id="H2MaxSessionStreams">H2MaxSessionStreams</a> <a name="h2maxsessionstreams" id="h2maxsessionstreams">Directive</a></h2> <table class="directive"> <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum number of active streams per HTTP/2 session.</td></tr> @@ -212,7 +305,7 @@ <p> This directive sets the maximum number of seconds a h2 worker may idle until it shuts itself down. This only happens while the number of - h2 workers exceeds <code>H2MinWorkers</code>. + h2 workers exceeds <code class="directive"><a href="#h2minworkers">H2MinWorkers</a></code>. </p> <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2MaxWorkerIdleSeconds 20</pre> </div> @@ -230,7 +323,7 @@ <p> This directive sets the maximum number of worker threads to spawn per child process for HTTP/2 processing. If this directive is not used, - <code>mod_http2</code> will chose a value suitable for the <code>mpm</code> + <code class="module"><a href="../mod/mod_http2.html">mod_http2</a></code> will chose a value suitable for the <code>mpm</code> module loaded. </p> <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2MaxWorkers 20</pre> @@ -249,7 +342,7 @@ <p> This directive sets the minimum number of worker threads to spawn per child process for HTTP/2 processing. If this directive is not used, - <code>mod_http2</code> will chose a value suitable for the <code>mpm</code> + <code class="module"><a href="../mod/mod_http2.html">mod_http2</a></code> will chose a value suitable for the <code>mpm</code> module loaded. </p> <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2MinWorkers 10</pre> @@ -286,14 +379,14 @@ in OpSec, this is a moving target and can be expected to evolve in the future. </p> <p> - One purpose of having these checks in mod_http2 is to enforce this + One purpose of having these checks in <code class="module"><a href="../mod/mod_http2.html">mod_http2</a></code> is to enforce this security level for all connections, not only those from browsers. The other purpose is to prevent the negotiation of HTTP/2 as a protocol should the requirements not be met. </p> <p> Ultimately, the security of the TLS connection is determined by the - server configuration directives for mod_ssl. + server configuration directives for <code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code>. </p> <div class="example"><h3>Example</h3><pre class="prettyprint lang-config">H2ModernTLSOnly off</pre> </div> @@ -365,7 +458,7 @@ <div class="directive-section"><h2><a name="H2PushDiarySize" id="H2PushDiarySize">H2PushDiarySize</a> <a name="h2pushdiarysize" id="h2pushdiarysize">Directive</a></h2> <table class="directive"> <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>H2 Server Push Diary Size</td></tr> -<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2PushDiarySize n</code></td></tr> +<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2PushDiarySize <em>n</em></code></td></tr> <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2PushDiarySize 256</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> @@ -381,7 +474,7 @@ <p> The push diary records a digest (currently using a 64 bit number) of pushed resources (their URL) to avoid duplicate pushes on the same connection. - These value are not persisted, so clients openeing a new connection + These value are not persisted, so clients opening a new connection will experience known pushes again. There is ongoing work to enable a client to disclose a digest of the resources it already has, so the diary maybe initialized by the client on each connection setup. @@ -400,13 +493,13 @@ <div class="directive-section"><h2><a name="H2PushPriority" id="H2PushPriority">H2PushPriority</a> <a name="h2pushpriority" id="h2pushpriority">Directive</a></h2> <table class="directive"> <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>H2 Server Push Priority</td></tr> -<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2PushPriority mime-type [after|before|interleaved] [weight]</code></td></tr> +<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2PushPriority <em>mime-type</em> [after|before|interleaved] [weight]</code></td></tr> <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2PushPriority * After 16</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> <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.4.18 and later. For having an - effect, a nghttp2 library version 1.5.0 or newer is necessary.</td></tr> + effect, a nghttp2 library version 1.5.0 or newer is necessary.</td></tr> </table> <p> This directive defines the priority handling of pushed responses @@ -421,19 +514,19 @@ <p> When a stream <em>depends</em> on another, say X depends on Y, then Y gets all bandwidth before X gets any. Note that this - does not men that Y will block X. If Y has no data to send, + does not mean that Y will block X. If Y has no data to send, all bandwidth allocated to Y can be used by X. </p> <p> When a stream has more than one dependant, say X1 and X2 both depend on Y, the <em>weight</em> determines the bandwidth allocation. If X1 and X2 have the same weight, they both get - half of the available bandwdith. If the weight of X1 is twice + half of the available bandwidth. If the weight of X1 is twice as large as that for X2, X1 gets twice the bandwidth of X2. </p> <p> Ultimately, every stream depends on the <em>root</em> stream which - gets all the bandwidht available, but never sends anything. So all + gets all the bandwidth available, but never sends anything. So all its bandwidth is distributed by weight among its children. Which either have data to send or distribute the bandwidth to their own children. And so on. If none of the children have data @@ -502,7 +595,7 @@ </p> <ol> <li>'*' is the only special content-type that matches all others. - 'image/*' will not work.</li> + 'image/*' will not work.</li> <li>The default dependency is 'After'. </li> <li>There are also default weights: for 'After' it is 16, 'interleaved' is 256. </li> @@ -594,71 +687,10 @@ H2PushPriority text/css interleaved # weight 256 default</pre> </div> <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> -<div class="directive-section"><h2><a name="H2StreamTimeout" id="H2StreamTimeout">H2StreamTimeout</a> <a name="h2streamtimeout" id="h2streamtimeout">Directive</a></h2> -<table class="directive"> -<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Timeout (in seconds) for idle HTTP/2 connections</td></tr> -<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2StreamTimeout seconds</code></td></tr> -<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2StreamTimeout 0</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> -<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.4.19 and later.</td></tr> -</table> - <p> - This directive sets the timeout for read/write operations on - HTTP/2 streams, e.g. individual requests. This can be used server wide or for specific - <code class="directive"><a href="../mod/core.html#virtualhost"><VirtualHost></a></code>s. - </p> - <p> - Due to the nature of HTTP/2, which sends multiple requests over a single - connection and has priority scheduling, individual streams might not - see input for much longer times than HTTP/1.1 requests would. - </p> - <p> - A value of 0 enforces no timeout, so could wait on chances to receive - input or write data indefinitely. This expose a server to - risks of thread exhaustion. - </p> - <p> - Depending on your handling of pushed streams, - priorities and general responsiveness, a site might need to increase - this value. For example, if you PUSH a large resource <em>before</em> - the requested one, the initial stream will not write until the - pushed resource is fully sent. - </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="H2Timeout" id="H2Timeout">H2Timeout</a> <a name="h2timeout" id="h2timeout">Directive</a></h2> -<table class="directive"> -<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Timeout (in seconds) for HTTP/2 connections</td></tr> -<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>H2Timeout seconds</code></td></tr> -<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>H2Timeout 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> -<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.4.19 and later.</td></tr> -</table> - <p> - This directive sets the timeout for read/write operations on - connections where HTTP/2 is negotiated. This can be used server wide or for specific - <code class="directive"><a href="../mod/core.html#virtualhost"><VirtualHost></a></code>s. - </p> - <p> - This directive is similar to the - <code class="directive"><a href="../mod/core.html#timeout"><Timeout></a></code>, but - applies only to HTTP/2 connections. - </p> - <p> - A value of 0 enforces no timeout. - </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="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#Syntax">Syntax:</a></th><td><code>H2TLSCoolDownSecs <em>seconds</em></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> @@ -673,8 +705,8 @@ H2PushPriority text/css interleaved # weight 256 default</pre> <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 + See <code class="directive"><a href="#h2tlswarmupsize">H2TLSWarmUpSize</a></code> for a + description of TLS warmup. <code class="directive">H2TLSCoolDownSecs</code> 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 @@ -697,7 +729,7 @@ H2PushPriority text/css interleaved # weight 256 default</pre> <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#Syntax">Syntax:</a></th><td><code>H2TLSWarmUpSize <em>amount</em></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> @@ -713,7 +745,7 @@ H2PushPriority text/css interleaved # weight 256 default</pre> </p> <p> Measurements by <a href="https://www.igvita.com">google performance - labs</a> show that best performance on TLS connections is reached, + 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> @@ -774,12 +806,12 @@ H2PushPriority text/css interleaved # weight 256 default</pre> 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 + See <code class="directive"><a href="#h2direct">H2Direct</a></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>. + 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> |