<?xml version="1.0"?>

<!--
  Copyright (C) Nginx, Inc.
  -->

<!DOCTYPE module SYSTEM "../../../../dtd/module.dtd">

<module name="Module ngx_http_spdy_module"
        link="/en/docs/http/ngx_http_spdy_module.html"
        lang="en"
        rev="10">

<section id="summary">

<para>
The <literal>ngx_http_spdy_module</literal> module provides experimental
support for <link url="http://www.chromium.org/spdy/spdy-protocol">SPDY</link>.
Currently,
<link url="http://www.chromium.org/spdy/spdy-protocol/spdy-protocol-draft3-1">draft
3.1</link> of SPDY protocol is implemented.
<note>
Before version 1.5.10,
<link url="http://www.chromium.org/spdy/spdy-protocol/spdy-protocol-draft2">draft
2</link> of SPDY protocol was implemented.
</note>
</para>

<para>
This module is not built by default, it should be enabled with
the <literal>--with-http_spdy_module</literal>
configuration parameter.
</para>

<para>
<note>
This module was superseded by the
<link doc="ngx_http_v2_module.xml">ngx_http_v2_module</link> module
in 1.9.5.
</note>
</para>

</section>


<section id="issues" name="Known Issues">

<para>
The module is experimental, caveat emptor applies.
</para>

<para>
Current implementation of SPDY protocol does not support “server push”.
</para>

<para>
In versions prior to 1.5.9, responses in SPDY connections could not be
<link doc="ngx_http_core_module.xml" id="limit_rate">rate limited</link>.
</para>

<para>
Buffering of a client request body cannot be disabled
regardless of
<link doc="ngx_http_proxy_module.xml" id="proxy_request_buffering"/>,
<link doc="ngx_http_fastcgi_module.xml" id="fastcgi_request_buffering"/>,
<link doc="ngx_http_uwsgi_module.xml" id="uwsgi_request_buffering"/>, and
<link doc="ngx_http_scgi_module.xml" id="scgi_request_buffering"/>
directive values.
</para>

</section>


<section id="example" name="Example Configuration">

<para>
<example>
server {
    listen 443 ssl spdy;

    ssl_certificate server.crt;
    ssl_certificate_key server.key;
    ...
}
</example>
<note>
Note that in order to accept both
<link doc="ngx_http_ssl_module.xml">HTTPS</link> and SPDY connections
simultaneously on the same port,
<link url="http://www.openssl.org">OpenSSL</link> library used should support
“Next Protocol Negotiation” TLS extension, available since OpenSSL
version 1.0.1.
</note>
</para>

</section>


<section id="directives" name="Directives">

<directive name="spdy_chunk_size">
<syntax><value>size</value></syntax>
<default>8k</default>
<context>http</context>
<context>server</context>
<context>location</context>
<appeared-in>1.5.9</appeared-in>

<para>
Sets the maximum size of chunks
into which the response body is
<link url="http://www.chromium.org/spdy/spdy-protocol/spdy-protocol-draft2#TOC-Data-frames">
sliced</link>.
A too low value results in higher overhead.
A too high value impairs prioritization due to
<link url="http://en.wikipedia.org/wiki/Head-of-line_blocking">
HOL blocking</link>.
</para>

</directive>


<directive name="spdy_headers_comp">
<syntax><value>level</value></syntax>
<default>0</default>
<context>http</context>
<context>server</context>

<para>
Sets the header compression <value>level</value> of a response in a range from
1 (fastest, less compression) to 9 (slowest, best compression).
The special value 0 turns off the header compression.
</para>

</directive>

</section>


<section id="variables" name="Embedded Variables">

<para>
The <literal>ngx_http_spdy_module</literal> module
supports the following embedded variables:
<list type="tag" compact="no">

<tag-name id="var_spdy"><var>$spdy</var></tag-name>
<tag-desc>
SPDY protocol version for SPDY connections,
or an empty string otherwise;
</tag-desc>

<tag-name id="var_spdy_request_priority"><var>$spdy_request_priority</var>
</tag-name>
<tag-desc>
request priority for SPDY connections,
or an empty string otherwise.
</tag-desc>

</list>
</para>

</section>

</module>