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174N/A<title>mod_xml2enc - Apache HTTP Server</title>
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174N/A<div id="page-content">
174N/A<div id="preamble"><h1>Apache Module mod_xml2enc</h1>
174N/A<div class="toplang">
174N/A<p><span>Available Languages: </span><a href="/en/mod/mod_xml2enc.html" title="English">&nbsp;en&nbsp;</a></p>
174N/A</div>
174N/A<table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Enhanced charset/internationalisation support for libxml2-based
844N/Afilter modules</td></tr>
844N/A<tr><th><a href="module-dict.html#Status">Status:</a></th><td>Base</td></tr>
174N/A<tr><th><a href="module-dict.html#ModuleIdentifier">Module�Identifier:</a></th><td>xml2enc_module</td></tr>
1258N/A<tr><th><a href="module-dict.html#SourceFile">Source�File:</a></th><td>mod_xml2enc.c</td></tr>
174N/A<tr><th><a href="module-dict.html#Compatibility">Compatibility:</a></th><td>Version 2.4 and later. Available as a third-party module
2899N/Afor 2.2.x versions</td></tr></table>
2899N/A<h3>Summary</h3>
3817N/A
3817N/A <p>This module provides enhanced internationalisation support for
3817N/A markup-aware filter modules such as <code class="module"><a href="/mod/mod_proxy_html.html">mod_proxy_html</a></code>.
3817N/A It can automatically detect the encoding of input data and ensure
174N/A they are correctly processed by the <a href="http://xmlsoft.org/">libxml2</a> parser, including converting to Unicode (UTF-8) where
174N/A necessary. It can also convert data to an encoding of choice
174N/A after markup processing, and will ensure the correct <var>charset</var>
206N/A value is set in the HTTP <var>Content-Type</var> header.</p>
206N/A</div>
181N/A<div id="quickview"><h3 class="directives">Directives</h3>
206N/A<ul id="toc">
206N/A<li><img alt="" src="/images/down.gif" /> <a href="#xml2encalias">xml2EncAlias</a></li>
206N/A<li><img alt="" src="/images/down.gif" /> <a href="#xml2encdefault">xml2EncDefault</a></li>
3823N/A<li><img alt="" src="/images/down.gif" /> <a href="#xml2startparse">xml2StartParse</a></li>
3823N/A</ul>
3823N/A<h3>Topics</h3>
3823N/A<ul id="topics">
3823N/A<li><img alt="" src="/images/down.gif" /> <a href="#usage">Usage</a></li>
3823N/A<li><img alt="" src="/images/down.gif" /> <a href="#api">Programming API</a></li>
3823N/A<li><img alt="" src="/images/down.gif" /> <a href="#sniffing">Detecting an Encoding</a></li>
3823N/A<li><img alt="" src="/images/down.gif" /> <a href="#output">Output Encoding</a></li>
3823N/A<li><img alt="" src="/images/down.gif" /> <a href="#alias">Unsupported Encodings</a></li>
3823N/A</ul><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div>
206N/A<div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
206N/A<div class="section">
206N/A<h2><a name="usage" id="usage">Usage</a></h2>
174N/A <p>There are two usage scenarios: with modules programmed to work
174N/A with mod_xml2enc, and with those that are not aware of it:</p>
174N/A <dl>
174N/A <dt>Filter modules enabled for mod_xml2enc</dt><dd>
206N/A <p>Modules such as <code class="module"><a href="/mod/mod_proxy_html.html">mod_proxy_html</a></code> version 3.1
206N/A and up use the <code>xml2enc_charset</code> optional function to retrieve
174N/A the charset argument to pass to the libxml2 parser, and may use the
174N/A <code>xml2enc_filter</code> optional function to postprocess to another
174N/A encoding. Using mod_xml2enc with an enabled module, no configuration
174N/A is necessary: the other module will configure mod_xml2enc for you
174N/A (though you may still want to customise it using the configuration
174N/A directives below).</p>
174N/A </dd>
174N/A <dt>Non-enabled modules</dt><dd>
174N/A <p>To use it with a libxml2-based module that isn't explicitly enabled for
174N/A mod_xml2enc, you will have to configure the filter chain yourself.
174N/A So to use it with a filter foo provided by a module mod_foo to
174N/A improve the latter's i18n support with HTML and XML, you could use</p>
206N/A <pre><code>
206N/A FilterProvider iconv xml2enc Content-Type $text/html
206N/A FilterProvider iconv xml2enc Content-Type $xml
174N/A FilterProvider markup foo Content-Type $text/html
174N/A FilterProvider markup foo Content-Type $xml
174N/A FilterChain iconv markup
174N/A </code></pre>
174N/A <p>mod_foo will now support any character set supported by either
174N/A (or both) of libxml2 or apr_xlate/iconv.</p>
727N/A </dd></dl>
727N/A</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
822N/A<div class="section">
822N/A<h2><a name="api" id="api">Programming API</a></h2>
727N/A <p>Programmers writing libxml2-based filter modules are encouraged to
727N/A enable them for mod_xml2enc, to provide strong i18n support for your
727N/A users without reinventing the wheel. The programming API is exposed in
727N/A <var>mod_xml2enc.h</var>, and a usage example is
822N/A <code class="module"><a href="/mod/mod_proxy_html.html">mod_proxy_html</a></code>.</p>
727N/A</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
181N/A<div class="section">
174N/A<h2><a name="sniffing" id="sniffing">Detecting an Encoding</a></h2>
3477N/A <p>Unlike <code class="module"><a href="/mod/mod_charset_lite.html">mod_charset_lite</a></code>, mod_xml2enc is designed
3477N/A to work with data whose encoding cannot be known in advance and thus
174N/A configured. It therefore uses 'sniffing' techniques to detect the
174N/A encoding of HTTP data as follows:</p>
181N/A <ol>
727N/A <li>If the HTTP <var>Content-Type</var> header includes a
727N/A <var>charset</var> parameter, that is used.</li>
727N/A <li>If the data start with an XML Byte Order Mark (BOM) or an
174N/A XML encoding declaration, that is used.</li>
181N/A <li>If an encoding is declared in an HTML <code>&lt;META&gt;</code>
174N/A element, that is used.</li>
3817N/A <li>If none of the above match, the default value set by
3817N/A <code class="directive">xml2EncDefault</code> is used.</li>
3817N/A </ol>
3817N/A <p>The rules are applied in order. As soon as a match is found,
3817N/A it is used and detection is stopped.</p>
3817N/A</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
3817N/A<div class="section">
3817N/A<h2><a name="output" id="output">Output Encoding</a></h2>
<p><a href="http://xmlsoft.org/">libxml2</a> always uses UTF-8 (Unicode)
internally, and libxml2-based filter modules will output that by default.
mod_xml2enc can change the output encoding through the API, but there
is currently no way to configure that directly.</p>
<p>Changing the output encoding should (in theory, at least) never be
necessary, and is not recommended due to the extra processing load on
the server of an unnecessary conversion.</p>
</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
<div class="section">
<h2><a name="alias" id="alias">Unsupported Encodings</a></h2>
<p>If you are working with encodings that are not supported by any of
the conversion methods available on your platform, you can still alias
them to a supported encoding using <code class="directive">xml2EncAlias</code>.</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="xml2EncAlias" id="xml2EncAlias">xml2EncAlias</a> <a name="xml2encalias" id="xml2encalias">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Recognise Aliases for encoding values</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>xml2EncAlias <var>charset alias [alias ...]</var></code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_xml2enc</td></tr>
</table>
<p>This server-wide directive aliases one or more encoding to another
encoding. This enables encodings not recognised by libxml2 to be handled
internally by libxml2's encoding support using the translation table for
a recognised encoding. This serves two purposes: to support character sets
(or names) not recognised either by libxml2 or iconv, and to skip
conversion for an encoding where it is known to be unnecessary.</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="xml2EncDefault" id="xml2EncDefault">xml2EncDefault</a> <a name="xml2encdefault" id="xml2encdefault">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets a default encoding to assume when absolutely no information
can be <a href="#sniffing">automatically detected</a></td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>xml2EncDefault <var>name</var></code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_xml2enc</td></tr>
<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Version 2.4.0 and later; available as a third-party
module for earlier versions.</td></tr>
</table>
<p>If you are processing data with known encoding but no encoding
information, you can set this default to help mod_xml2enc process
the data correctly. For example, to work with the default value
of Latin1 (<var>iso-8859-1</var> specified in HTTP/1.0, use</p>
<pre class="prettyprint lang-config">xml2EncDefault iso-8859-1</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="xml2StartParse" id="xml2StartParse">xml2StartParse</a> <a name="xml2startparse" id="xml2startparse">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Advise the parser to skip leading junk.</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>xml2StartParse <var>element [element ...]</var></code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_xml2enc</td></tr>
</table>
<p>Specify that the markup parser should start at the first instance
of any of the elements specified. This can be used as a workaround
where a broken backend inserts leading junk that messes up the parser (<a href="http://bahumbug.wordpress.com/2006/10/12/mod_proxy_html-revisited/">example here</a>).</p>
<p>It should never be used for XML, nor well-formed HTML.</p>
</div>
</div>
<div class="bottomlang">
<p><span>Available Languages: </span><a href="/en/mod/mod_xml2enc.html" title="English">&nbsp;en&nbsp;</a></p>
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