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diff --git a/docs/manual/rewrite/rewritemap.html.en b/docs/manual/rewrite/rewritemap.html.en new file mode 100644 index 00000000..79fc3f21 --- /dev/null +++ b/docs/manual/rewrite/rewritemap.html.en @@ -0,0 +1,417 @@ +<?xml version="1.0" encoding="ISO-8859-1"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head><!-- + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + This file is generated from xml source: DO NOT EDIT + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + --> +<title>Using RewriteMap - Apache HTTP Server</title> +<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" /> +<link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" /> +<link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /> +<link href="../images/favicon.ico" rel="shortcut icon" /></head> +<body id="manual-page"><div id="page-header"> +<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p> +<p class="apache">Apache HTTP Server Version 2.2</p> +<img alt="" src="../images/feather.gif" /></div> +<div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div> +<div id="path"> +<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="../">Version 2.2</a> > <a href="./">Rewrite</a></div><div id="page-content"><div id="preamble"><h1>Using RewriteMap</h1> +<div class="toplang"> +<p><span>Available Languages: </span><a href="../en/rewrite/rewritemap.html" title="English"> en </a></p> +</div> + + + <p>This document supplements the <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> +<a href="../mod/mod_rewrite.html">reference documentation</a>. It describes +the use of the <code class="directive"><a href="../mod/mod_rewrite.html#rewritemap">RewriteMap</a></code> directive, +and provides examples of each of the various <code>RewriteMap</code> types.</p> + + <div class="warning">Note that many of these examples won't work unchanged in your +particular server configuration, so it's important that you understand +them, rather than merely cutting and pasting the examples into your +configuration.</div> + + </div> +<div id="quickview"><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#introduction">Introduction</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#txt">txt: Plain text maps</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#rnd">rnd: Randomized Plain Text</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#dbm">dbm: DBM Hash File</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#int">int: Internal Function</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#prg">prg: External Rewriting Program</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#summary">Summary</a></li> +</ul><h3>See also</h3><ul class="seealso"><li><a href="../mod/mod_rewrite.html">Module documentation</a></li><li><a href="intro.html">mod_rewrite introduction</a></li><li><a href="remapping.html">Redirection and remapping</a></li><li><a href="access.html">Controlling access</a></li><li><a href="vhosts.html">Virtual hosts</a></li><li><a href="proxy.html">Proxying</a></li><li><a href="advanced.html">Advanced techniques and tricks</a></li><li><a href="avoid.html">When not to use mod_rewrite</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="introduction" id="introduction">Introduction</a></h2> + + + <p> + The <code class="directive"><a href="../mod/mod_rewrite.html#rewritemap">RewriteMap</a></code> directive + defines an external function which can be called in the context of + <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> or + <code class="directive"><a href="../mod/mod_rewrite.html#rewritecond">RewriteCond</a></code> directives to + perform rewriting that is too complicated, or too specialized to be + performed just by regular expressions. The source of this lookup can + be any of the types listed in the sections below, and enumerated in + the <code class="directive"><a href="../mod/mod_rewrite.html#rewritemap">RewriteMap</a></code> reference + documentation.</p> + + <p>The syntax of the <code>RewriteMap</code> directive is as + follows:</p> + +<div class="example"><p><code> +RewriteMap <em>MapName</em> <em>MapType</em>:<em>MapSource</em> +</code></p></div> + + <p>The <a id="mapfunc" name="mapfunc"><em>MapName</em></a> is an + arbitray name that you assign to the map, and which you will use in + directives later on. Arguments are passed to the map via the + following syntax:</p> + + <p class="indent"> + <strong> + <code>${</code> <em>MapName</em> <code>:</code> <em>LookupKey</em> + <code>}</code> <br /> <code>${</code> <em>MapName</em> <code>:</code> + <em>LookupKey</em> <code>|</code> <em>DefaultValue</em> <code>}</code> + </strong> + </p> + + <p>When such a construct occurs, the map <em>MapName</em> is + consulted and the key <em>LookupKey</em> is looked-up. If the + key is found, the map-function construct is substituted by + <em>SubstValue</em>. If the key is not found then it is + substituted by <em>DefaultValue</em> or by the empty string + if no <em>DefaultValue</em> was specified.</p> + + <p>For example, you might define a + <code class="directive">RewriteMap</code> as:</p> + <div class="example"><p><code> + RewriteMap examplemap txt:/path/to/file/map.txt + </code></p></div> + <p>You would then be able to use this map in a + <code class="directive">RewriteRule</code> as follows:</p> +<div class="example"><p><code> + RewriteRule ^/ex/(.*) ${examplemap:$1} +</code></p></div> + +<p>A default value can be specified in the event that nothing is found +in the map:</p> + +<div class="example"><p><code> +RewriteRule ^/ex/(.*) ${examplemap:$1|/not_found.html} +</code></p></div> + +<div class="note"><h3>Per-directory and .htaccess context</h3> +<p> +The <code>RewriteMap</code> directive may not be used in +<Directory> sections or <code>.htaccess</code> files. You must +declare the map in server or virtualhost context. You may use the map, +once created, in your <code>RewriteRule</code> and +<code>RewriteCond</code> directives in those scopes. You just can't +<strong>declare</strong> it in those scopes. +</p> +</div> + +<p>The sections that follow describe the various <em>MapType</em>s that +may be used, and give examples of each.</p> + </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="txt" id="txt">txt: Plain text maps</a></h2> + + + <p>When a MapType of <code>txt</code> is used, the MapSource is a filesystem path to a + plain-text mapping file, containing space-separated key/value pair + per line. Optionally, a line may be contain a comment, starting with + a '#' character.</p> + + <p>For example, the following might be valid entries in a map + file.</p> + + <p class="indent"> + # Comment line<br /> + <strong><em>MatchingKey</em> <em>SubstValue</em></strong><br /> + <strong><em>MatchingKey</em> <em>SubstValue</em></strong> # comment<br /> + </p> + + <p>When the RewriteMap is invoked the argument is looked for in the + first argument of a line, and, if found, the substitution value is + returned.</p> + + <p>For example, we might use a mapfile to translate product names to + product IDs for easier-to-remember URLs, using the following + recipe:</p> + + <div class="example"><h3>Product to ID configuration</h3><p><code> + RewriteMap product2id txt:/etc/apache2/productmap.txt<br /> + RewriteRule ^/product/(.*) /prods.php?id=${product2id:$1|NOTFOUND} [PT] + </code></p></div> + + <p>We assume here that the <code>prods.php</code> script knows what + to do when it received an argument of <code>id=NOTFOUND</code> when + a product is not found in the lookup map.</p> + + <p>The file <code>/etc/apache2/productmap.txt</code> then contains + the following:</p> + + <div class="example"><h3>Product to ID map</h3><p><code> +##<br /> +## productmap.txt - Product to ID map file<br /> +##<br /> +<br /> +television 993<br /> +stereo 198<br /> +fishingrod 043<br /> +basketball 418<br /> +telephone 328 + </code></p></div> + + <p>Thus, when <code>http://example.com/product/television</code> is + requested, the <code>RewriteRule</code> is applied, and the request + is internally mapped to <code>/prods.php?id=993</code>.</p> + + <div class="note"><h3>Note: .htaccess files</h3> + The example given is crafted to be used in server or virtualhost + scope. If you're planning to use this in a <code>.htaccess</code> + file, you'll need to remove the leading slash from the rewrite + pattern in order for it to match anything: + <div class="example"><p><code> + RewriteRule ^product/(.*) /prods.php?id=${product2id:$1|NOTFOUND} [PT] + </code></p></div> + </div> + + <div class="note"><h3>Cached lookups</h3> + <p> + The looked-up keys are cached by httpd until the <code>mtime</code> + (modified time) of the mapfile changes, or the httpd server is + restarted. This ensures better performance on maps that are called + by many requests. + </p> + </div> + + </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="rnd" id="rnd">rnd: Randomized Plain Text</a></h2> + + + <p>When a MapType of <code>rnd</code> is used, the MapSource is a + filesystem path to a plain-text mapping file, each line of which + contains a key, and one or more values separated by <code>|</code>. + One of these values will be chosen at random if the key is + matched.</p> + + <p>For example, you might use the following map + file and directives to provide a random load balancing between + several back-end server, via a reverse-proxy. Images are sent + to one of the servers in the 'static' pool, while everything + else is sent to one of the 'dynamic' pool.</p> + + <div class="example"><h3>Rewrite map file</h3><p><code> +##<br /> +## map.txt -- rewriting map<br /> +##<br /> +<br /> +static www1|www2|www3|www4<br /> +dynamic www5|www6 + </code></p></div> + + <div class="example"><h3>Configuration directives</h3><p><code> + RewriteMap servers rnd:/path/to/file/map.txt<br /> + <br /> + RewriteRule ^/(.*\.(png|gif|jpg)) http://${servers:static}/$1 [NC,P,L]<br /> + RewriteRule ^/(.*) http://${servers:dynamic}/$1 [P,L] + </code></p></div> + + <p>So, when an image is requested and the first of these rules is + matched, <code>RewriteMap</code> looks up the string + <code>static</code> in the map file, which returns one of the + specified hostnames at random, which is then used in the + <code>RewriteRule</code> target.</p> + + <p>If you wanted to have one of the servers more likely to be chosen + (for example, if one of the server has more memory than the others, + and so can handle more requests) simply list it more times in the + map file.</p> + + <div class="example"><p><code> +static www1|www1|www2|www3|www4 + </code></p></div> + + </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="dbm" id="dbm">dbm: DBM Hash File</a></h2> + + + <p>When a MapType of <code>dbm</code> is used, the MapSource is a + filesystem path to a DBM database file containing key/value pairs to + be used in the mapping. This works exactly the same way as the + <code>txt</code> map, but is much faster, because a DBM is indexed, + whereas a text file is not. This allows more rapid access to the + desired key.</p> + + <p>You may optionally specify a particular dbm type:</p> + + <div class="example"><p><code> + RewriteMap examplemap dbm=sdbm:/etc/apache/mapfile.dbm + </code></p></div> + + <p>The type can be sdbm, gdbm, ndbm or db. + However, it is recommended that you just use the <a href="../programs/httxt2dbm.html">httxt2dbm</a> utility that is + provided with Apache HTTP Server, as it will use the correct DBM library, + matching the one that was used when httpd itself was built.</p> + + <p>To create a dbm file, first create a text map file as described + in the <a href="#txt">txt</a> section. Then run + <code>httxt2dbm</code>:</p> + +<div class="example"><p><code> +$ httxt2dbm -i mapfile.txt -o mapfile.map +</code></p></div> + +<p>You can then reference the resulting file in your +<code>RewriteMap</code> directive:</p> + +<div class="example"><p><code> +RewriteMap mapname dbm:/etc/apache/mapfile.map +</code></p></div> + +<div class="note"> +<p>Note that with some dbm types, more than one file is generated, with +a common base name. For example, you may have two files named +<code>mapfile.map.dir</code> and <code>mapfiile.map.pag</code>. This is +normal, and you need only use the base name <code>mapfile.map</code> in +your <code>RewriteMap</code> directive.</p> +</div> + +<div class="note"><h3>Cached lookups</h3> +<p> +The looked-up keys are cached by httpd until the <code>mtime</code> +(modified time) of the mapfile changes, or the httpd server is +restarted. This ensures better performance on maps that are called +by many requests. +</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="int" id="int">int: Internal Function</a></h2> + + + <p>When a MapType of <code>int</code> is used, the MapSource is one + of the available internal RewriteMap functions. Module authors can provide + additional internal functions by registering them with the + <code>ap_register_rewrite_mapfunc</code> API. + The functions that are provided by default are: + </p> + + <ul> + <li><strong>toupper</strong>:<br /> + Converts the key to all upper case.</li> + <li><strong>tolower</strong>:<br /> + Converts the key to all lower case.</li> + <li><strong>escape</strong>:<br /> + Translates special characters in the key to + hex-encodings.</li> + <li><strong>unescape</strong>:<br /> + Translates hex-encodings in the key back to + special characters.</li> + </ul> + + <p> + To use one of these functions, create a <code>RewriteMap</code> referencing + the int function, and then use that in your <code>RewriteRule</code>: + </p> + + <div class="example"><h3>Redirect a URI to an all-lowercase version of itself</h3><p><code> + RewriteMap lc int:tolower<br /> + RewriteRule (.*[A-Z]+.*) ${lc:$1} [R] + </code></p></div> + + <div class="note"> + <p>Please note that the example offered here is for + illustration purposes only, and is not a recommendation. If you want + to make URLs case-insensitive, consider using + <code class="module"><a href="../mod/mod_speling.html">mod_speling</a></code> instead. + </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="prg" id="prg">prg: External Rewriting Program</a></h2> + + <p>When a MapType of <code>prg</code> is used, the MapSource is a + filesystem path to an executable program which will providing the + mapping behavior. This can be a compiled binary file, or a program + in an interpreted language such as Perl or Python.</p> + + <p>This program is started once, when the Apache HTTP Server is + started, and then communicates with the rewriting engine via + <code>STDIN</code> and <code>STDOUT</code>. That is, for each map + function lookup, it expects one argument via <code>STDIN</code>, and + should return one new-line terminated response string on + <code>STDOUT</code>. If there is no corresponding lookup value, the + map program should return the four-character string + "<code>NULL</code>" to indicate this.</p> + + <p>External rewriting programs are not started if they're defined in + a context that does not have <code class="directive"><a href="../mod/mod_rewrite.html#rewriteengine">RewriteEngine</a></code> set to + <code>on</code>.</p> + + <p>A simple example is shown here which will replace all dashes with + underscores in a request URI.</p> + + <div class="example"><h3>Rewrite configuration</h3><p><code> + RewriteMap d2u prg:/www/bin/dash2under.pl<br /> + RewriteRule - ${d2u:%{REQUEST_URI}} + </code></p></div> + + <div class="example"><h3>dash2under.pl</h3><p><code> + #!/usr/bin/perl<br /> + $| = 1; # Turn off I/O buffering<br /> + while (<STDIN>) {<br /> + <span class="indent"> + s/-/_/g; # Replace dashes with underscores<br /> + print $_;<br /> + </span> + }<br /> + </code></p></div> + +<div class="note"><h3>Caution!</h3> +<ul> +<li>Keep your rewrite map program as simple as possible. If the program +hangs, it will cause httpd to wait indefinitely for a response from the +map, which will, in turn, cause httpd to stop responding to +requests.</li> +<li>Be sure to turn off buffering in your program. In Perl this is done +by the second line in the example script: <code>$| = 1;</code> This will +of course vary in other languages. Buffered I/O will cause httpd to wait +for the output, and so it will hang.</li> +<li>Remember that there is only one copy of the program, started at +server startup. All requests will need to go through this one bottleneck. +This can cause significant slowdowns if many requests must go through +this process, or if the script itself is very slow.</li> +</ul> +</div> + +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="summary" id="summary">Summary</a></h2> + + + <p>The <code class="directive">RewriteMap</code> directive can occur more than + once. For each mapping-function use one + <code class="directive">RewriteMap</code> directive to declare its rewriting + mapfile.</p> + + <p>While you cannot <strong>declare</strong> a map in + per-directory context (<code>.htaccess</code> files or + <Directory> blocks) it is possible to + <strong>use</strong> this map in per-directory context. </p> + + </div></div> +<div class="bottomlang"> +<p><span>Available Languages: </span><a href="../en/rewrite/rewritemap.html" title="English"> en </a></p> +</div><div id="footer"> +<p class="apache">Copyright 2011 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p> +<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p></div> +</body></html>
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