file.</p>
<p class="indent">
- # Comment line
+ # Comment line<br />
<strong><em>MatchingKey</em> <em>SubstValue</em></strong><br />
<strong><em>MatchingKey</em> <em>SubstValue</em></strong> # comment<br />
</p>
<div class="section">
<h2><a name="rnd" id="rnd">rnd: Randomized Plain Text</a></h2>
- <p>MapType: <code>rnd</code>, MapSource: Unix filesystem
- path to valid regular file</p>
- <p>This is identical to the Standard Plain Text variant
- above but with a special post-processing feature: After
- looking up a value it is parsed according to contained
- ``<code>|</code>'' characters which have the meaning of
- ``or''. In other words they indicate a set of
- alternatives from which the actual returned value is
- chosen randomly. 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>
- <p>Example:</p>
+
+ <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><pre>
##
## map.txt -- rewriting map
static www1|www2|www3|www4
dynamic www5|www6
</pre></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}/$1 [P,L]
-</code></p></div>
+ RewriteMap servers rnd:/path/to/file/map.txt<br />
+ <br />
+ RewriteRule ^/(.*\.(png|gif|jpg)) http://${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>
file.</p>
<p class="indent">
- # Comment line
+ # Comment line<br />
<strong><em>MatchingKey</em> <em>SubstValue</em></strong><br />
<strong><em>MatchingKey</em> <em>SubstValue</em></strong> # comment<br />
</p>
</section>
<section id="rnd">
<title>rnd: Randomized Plain Text</title>
- <p>MapType: <code>rnd</code>, MapSource: Unix filesystem
- path to valid regular file</p>
- <p>This is identical to the Standard Plain Text variant
- above but with a special post-processing feature: After
- looking up a value it is parsed according to contained
- ``<code>|</code>'' characters which have the meaning of
- ``or''. In other words they indicate a set of
- alternatives from which the actual returned value is
- chosen randomly. 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>
- <p>Example:</p>
- <example>
- <title>Rewrite map file</title>
+
+ <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>
+
+ <example><title>Rewrite map file</title>
<pre>
##
## map.txt -- rewriting map
dynamic www5|www6
</pre>
</example>
+
<example><title>Configuration directives</title>
-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}/$1 [P,L]
-</example>
+ RewriteMap servers rnd:/path/to/file/map.txt<br/>
+ <br/>
+ RewriteRule ^/(.*\.(png|gif|jpg)) http://${servers:static}/$1 [NC,P,L]<br/>
+ RewriteRule ^/(.*) http://${servers:dynamic}/$1 [P,L]
+ </example>
+
+ <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>
+
+ <example>
+static www1|www1|www2|www3|www4
+ </example>
+
</section>
+
<section id="dbm">
<title>dbm: DBM Hash File</title>
<p>MapType:
projects / apache / commitdiff