mod_deflate.html.en

最新apache的源代码

          SetInputFilter DEFLATE<br />
        </span>
        &lt;/Location&gt;
      </code></p></div>
      
      <p>Now if a request contains a <code>Content-Encoding:
      gzip</code> header, the body will be automatically decompressed.
      Few browsers have the ability to gzip request bodies. However,
      some special applications actually do support request
      compression, for instance some <a href="http://www.webdav.org">WebDAV</a> clients.</p>

      <div class="warning"><h3>Note on Content-Length</h3>
        <p>If you evaluate the request body yourself, <em>don't trust
        the <code>Content-Length</code> header!</em>
        The Content-Length header reflects the length of the
        incoming data from the client and <em>not</em> the byte count of
        the decompressed data stream.</p>
      </div>
    
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="proxies" id="proxies">Dealing with proxy servers</a></h2>

    <p>The <code class="module"><a href="../mod/mod_deflate.html">mod_deflate</a></code> module sends a <code>Vary:
    Accept-Encoding</code> HTTP response header to alert proxies that
    a cached response should be sent only to clients that send the
    appropriate <code>Accept-Encoding</code> request header.  This
    prevents compressed content from being sent to a client that will
    not understand it.</p>

    <p>If you use some special exclusions dependent
    on, for example, the <code>User-Agent</code> header, you must 
    manually configure an addition to the <code>Vary</code> header
    to alert proxies of the additional restrictions.  For example,
    in a typical configuration where the addition of the <code>DEFLATE</code>
    filter depends on the <code>User-Agent</code>, you should add:</p>

    <div class="example"><p><code>
      Header append Vary User-Agent
    </code></p></div>
    
    <p>If your decision about compression depends on other information
    than request headers (<em>e.g.</em> HTTP version), you have to set the
    <code>Vary</code> header to the value <code>*</code>. This prevents
    compliant proxies from caching entirely.</p>

    <div class="example"><h3>Example</h3><p><code>
      Header set Vary *
    </code></p></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="DeflateBufferSize" id="DeflateBufferSize">DeflateBufferSize</a> <a name="deflatebuffersize" id="deflatebuffersize">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Fragment size to be compressed at one time by zlib</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DeflateBufferSize <var>value</var></code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>DeflateBufferSize 8096</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_deflate</td></tr>
</table>
    <p>The <code class="directive">DeflateBufferSize</code> directive specifies
    the size in bytes of the fragments that zlib should compress at one
    time.</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="DeflateCompressionLevel" id="DeflateCompressionLevel">DeflateCompressionLevel</a> <a name="deflatecompressionlevel" id="deflatecompressionlevel">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>How much compression do we apply to the output</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DeflateCompressionLevel <var>value</var></code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Zlib's default</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_deflate</td></tr>
<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>This directive is available since Apache 2.0.45</td></tr>
</table>
    <p>The <code class="directive">DeflateCompressionLevel</code> directive specifies
        what level of compression should be used, the higher the value, 
        the better the compression, but the more CPU time is required to
        achieve this.</p>
    <p>The value must between 1 (less compression) and 9 (more compression).</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="DeflateFilterNote" id="DeflateFilterNote">DeflateFilterNote</a> <a name="deflatefilternote" id="deflatefilternote">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Places the compression ratio in a note for logging</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DeflateFilterNote [<var>type</var>] <var>notename</var></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_deflate</td></tr>
<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td><var>type</var> is available since Apache 2.0.45</td></tr>
</table>
    <p>The <code class="directive">DeflateFilterNote</code> directive
    specifies that a note about compression ratios should be attached
    to the request. The name of the note is the value specified for
    the directive. You can use that note for statistical purposes by
    adding the value to your <a href="../logs.html#accesslog">access log</a>.</p>

    <div class="example"><h3>Example</h3><p><code>
      DeflateFilterNote ratio<br />
      <br />
      LogFormat '"%r" %b (%{ratio}n) "%{User-agent}i"' deflate<br />
      CustomLog logs/deflate_log deflate
    </code></p></div>

    <p>If you want to extract more accurate values from your logs, you
    can use the <var>type</var> argument to specify the type of data
    left as note for logging. <var>type</var> can be one of:</p>

    <dl>
      <dt><code>Input</code></dt>
      <dd>Store the byte count of the filter's input stream in the note.</dd>

      <dt><code>Output</code></dt>
      <dd>Store the byte count of the filter's output stream in the note.</dd>

      <dt><code>Ratio</code></dt>
      <dd>Store the compression ratio (<code>output/input * 100</code>)
      in the note. This is the default, if the <var>type</var> argument
      is omitted.</dd>
    </dl>

    <p>Thus you may log it this way:</p>

    <div class="example"><h3>Accurate Logging</h3><p><code>
      DeflateFilterNote Input instream<br />
      DeflateFilterNote Output outstream<br />
      DeflateFilterNote Ratio ratio<br />
      <br />
      LogFormat '"%r" %{outstream}n/%{instream}n (%{ratio}n%%)' deflate<br />
      CustomLog logs/deflate_log deflate
    </code></p></div>

<h3>See also</h3>
<ul>
<li><code class="module"><a href="../mod/mod_log_config.html">mod_log_config</a></code></li>
</ul>
</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="DeflateMemLevel" id="DeflateMemLevel">DeflateMemLevel</a> <a name="deflatememlevel" id="deflatememlevel">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>How much memory should be used by zlib for compression</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DeflateMemLevel <var>value</var></code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>DeflateMemLevel 9</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_deflate</td></tr>
</table>
    <p>The <code class="directive">DeflateMemLevel</code> directive specifies
    how much memory should be used by zlib for compression
    (a value between 1 and 9).</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="DeflateWindowSize" id="DeflateWindowSize">DeflateWindowSize</a> <a name="deflatewindowsize" id="deflatewindowsize">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Zlib compression window size</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DeflateWindowSize <var>value</var></code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>DeflateWindowSize 15</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_deflate</td></tr>
</table>
    <p>The <code class="directive">DeflateWindowSize</code> directive specifies the
    zlib compression window size (a value between 1 and 15). Generally, the
    higher the window size, the higher can the compression ratio be expected.</p>

</div>
</div>
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