rbowen at apache
Nov 4, 2009, 5:55 PM
Post #1 of 1
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svn commit: r832971 - in /httpd/httpd/trunk/docs/manual/rewrite: advanced.html.en advanced.xml
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Author: rbowen
Date: Thu Nov 5 01:55:25 2009
New Revision: 832971
URL: http://svn.apache.org/viewvc?rev=832971&view=rev
Log:
Moves the 'sharding' rule into the 'advanced' doc.
Modified:
httpd/httpd/trunk/docs/manual/rewrite/advanced.html.en
httpd/httpd/trunk/docs/manual/rewrite/advanced.xml
Modified: httpd/httpd/trunk/docs/manual/rewrite/advanced.html.en
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/docs/manual/rewrite/advanced.html.en?rev=832971&r1=832970&r2=832971&view=diff
==============================================================================
--- httpd/httpd/trunk/docs/manual/rewrite/advanced.html.en (original)
+++ httpd/httpd/trunk/docs/manual/rewrite/advanced.html.en Thu Nov 5 01:55:25 2009
@@ -33,7 +33,64 @@
</div>
<div id="quickview"><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></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="sharding" id="sharding">URL-based sharding accross multiple backends</a></h2>
+
+
+
+ <dl>
+ <dt>Description:</dt>
+
+ <dd>
+ <p>A common technique for distributing the burden of
+ server load or storage space is called "sharding".
+ When using this method, a front-end server will use the
+ url to consistently "shard" users or objects to separate
+ backend servers.</p>
+ </dd>
+
+ <dt>Solution:</dt>
+
+ <dd>
+ <p>A mapping is maintained, from users to target servers, in
+ external map files. They look like:</p>
+
+<div class="example"><pre>
+user1 physical_host_of_user1
+user2 physical_host_of_user2
+: :
+</pre></div>
+
+ <p>We put this into a <code>map.users-to-hosts</code> file. The
+ aim is to map;</p>
+
+<div class="example"><pre>
+/u/user1/anypath
+</pre></div>
+
+ <p>to</p>
+
+<div class="example"><pre>
+http://physical_host_of_user1/u/user/anypath
+</pre></div>
+
+ <p>thus every URL path need not be valid on every backend physical
+ host. The following ruleset does this for us with the help of the map
+ files assuming that server0 is a default server which will be used if
+ a user has no entry in the map):</p>
+
+<div class="example"><pre>
+RewriteEngine on
+
+RewriteMap users-to-hosts txt:/path/to/map.users-to-hosts
+
+RewriteRule ^/u/<strong>([^/]+)</strong>/?(.*) http://<strong>${users-to-hosts:$1|server0}</strong>/u/$1/$2
+</pre></div>
+ </dd>
+ </dl>
+
+</div></div>
<div class="bottomlang">
<p><span>Available Languages: </span><a href="../en/rewrite/avoid.html" title="English"> en </a></p>
</div><div id="footer">
Modified: httpd/httpd/trunk/docs/manual/rewrite/advanced.xml
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/docs/manual/rewrite/advanced.xml?rev=832971&r1=832970&r2=832971&view=diff
==============================================================================
--- httpd/httpd/trunk/docs/manual/rewrite/advanced.xml (original)
+++ httpd/httpd/trunk/docs/manual/rewrite/advanced.xml Thu Nov 5 01:55:25 2009
@@ -40,5 +40,61 @@
<seealso><a href="../mod/mod_rewrite.html">Module documentation</a></seealso>
<seealso><a href="intro.html">mod_rewrite introduction</a></seealso>
+<section id="sharding">
+
+ <title>URL-based sharding accross multiple backends</title>
+
+ <dl>
+ <dt>Description:</dt>
+
+ <dd>
+ <p>A common technique for distributing the burden of
+ server load or storage space is called "sharding".
+ When using this method, a front-end server will use the
+ url to consistently "shard" users or objects to separate
+ backend servers.</p>
+ </dd>
+
+ <dt>Solution:</dt>
+
+ <dd>
+ <p>A mapping is maintained, from users to target servers, in
+ external map files. They look like:</p>
+
+<example><pre>
+user1 physical_host_of_user1
+user2 physical_host_of_user2
+: :
+</pre></example>
+
+ <p>We put this into a <code>map.users-to-hosts</code> file. The
+ aim is to map;</p>
+
+<example><pre>
+/u/user1/anypath
+</pre></example>
+
+ <p>to</p>
+
+<example><pre>
+http://physical_host_of_user1/u/user/anypath
+</pre></example>
+
+ <p>thus every URL path need not be valid on every backend physical
+ host. The following ruleset does this for us with the help of the map
+ files assuming that server0 is a default server which will be used if
+ a user has no entry in the map):</p>
+
+<example><pre>
+RewriteEngine on
+
+RewriteMap users-to-hosts txt:/path/to/map.users-to-hosts
+
+RewriteRule ^/u/<strong>([^/]+)</strong>/?(.*) http://<strong>${users-to-hosts:$1|server0}</strong>/u/$1/$2
+</pre></example>
+ </dd>
+ </dl>
+
+</section>
</manualpage>
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