mirror of
https://github.com/yasuhirokimura/db18
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Yasuhiro KIMURA
194 lines
7.7 KiB
HTML
194 lines
7.7 KiB
HTML
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>Chapter 23. Berkeley DB Extensions</title>
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<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
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<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
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<link rel="start" href="index.html" title="Berkeley DB Programmer's Reference Guide" />
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<link rel="up" href="index.html" title="Berkeley DB Programmer's Reference Guide" />
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<link rel="prev" href="tcl_faq.html" title="Tcl FAQ" />
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<link rel="next" href="ext_perl.html" title="Using Berkeley DB with Perl" />
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</head>
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<body>
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<div xmlns="" class="navheader">
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<div class="libver">
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<p>Library Version 18.1.40</p>
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</div>
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">Chapter 23. Berkeley DB Extensions </th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="tcl_faq.html">Prev</a> </td>
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<th width="60%" align="center"> </th>
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<td width="20%" align="right"> <a accesskey="n" href="ext_perl.html">Next</a></td>
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</tr>
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</table>
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<hr />
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</div>
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<div class="chapter" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title"><a id="ext"></a>Chapter 23. Berkeley DB Extensions </h2>
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</div>
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</div>
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</div>
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<div class="toc">
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<p>
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<b>Table of Contents</b>
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</p>
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<dl>
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<dt>
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<span class="sect1">
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<a href="ext.html#ext_mod">Using Berkeley DB with Apache</a>
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</span>
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</dt>
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<dt>
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<span class="sect1">
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<a href="ext_perl.html">Using Berkeley DB with Perl</a>
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</span>
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</dt>
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<dt>
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<span class="sect1">
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<a href="ext_php.html">Using Berkeley DB with PHP</a>
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</span>
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</dt>
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</dl>
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</div>
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<div class="sect1" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title" style="clear: both"><a id="ext_mod"></a>Using Berkeley DB with Apache</h2>
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</div>
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</div>
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</div>
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<p>
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A mod_db4 Apache module is included in the Berkeley DB
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distribution, providing a safe framework for running Berkeley
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DB applications in an Apache 1.3 environment. Apache natively
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provides no interface for communication between threads or
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processes, so the mod_db4 module exists to provide this
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communication.
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</p>
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<p>
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In general, it is dangerous to run Berkeley DB in a
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multiprocess system without some facility to coordinate
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database recovery between processes sharing the database
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environment after application or system failure. Failure to
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run recovery after failure can include process hangs and an
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inability to access the database environment. The mod_db4
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Apache module oversees the proper management of Berkeley DB
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database environment resources. Developers building
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applications using Berkeley DB as the storage manager within
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an Apache module should employ this technique for proper
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resource management.
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</p>
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<p>
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Specifically, mod_db4 provides the following
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facilities:
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</p>
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<div class="orderedlist">
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<ol type="1">
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<li>
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New constructors for <a href="../api_reference/C/env.html" class="olink">DB_ENV</a> and <a href="../api_reference/C/db.html" class="olink">DB</a> handles, which
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install replacement open/close methods.
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</li>
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<li>
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Transparent caching of open <a href="../api_reference/C/env.html" class="olink">DB_ENV</a> and <a href="../api_reference/C/db.html" class="olink">DB</a>
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handles.
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</li>
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<li>
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Reference counting on all structures, allowing the
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module to detect the initial opening of any managed
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database and automatically perform recovery.
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</li>
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<li>
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Automatic detection of unexpected failures
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(segfaults, or a module actually calling exit() and
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avoiding shut down phases), and automatic termination of
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all child processes with open database resources to
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attempt consistency.
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</li>
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</ol>
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</div>
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<p>
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mod_db4 is designed to be used as an alternative interface
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to Berkeley DB. To have another Apache module (for example,
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mod_foo) use mod_db4, do not link mod_foo against the Berkeley
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DB library. In your mod_foo makefile, you should:
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</p>
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<pre class="programlisting">#include "mod_db4_export.h"</pre>
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<p>
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and add your Apache include directory to your
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CPPFLAGS.
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</p>
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<p>
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In mod_foo, to create a mod_db4 managed <a href="../api_reference/C/env.html" class="olink">DB_ENV</a> handle, use
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the following:
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</p>
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<pre class="programlisting">int mod_db4_db_env_create(DB_ENV **dbenvp, u_int32_t flags);</pre>
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<p>
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which takes identical arguments to <a href="../api_reference/C/envcreate.html" class="olink">db_env_create()</a>.
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</p>
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<p>
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To create a mod_db4 managed <a href="../api_reference/C/db.html" class="olink">DB</a> handle, use the
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following:
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</p>
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<pre class="programlisting">int mod_db4_db_create(DB **dbp, DB_ENV *dbenv, u_int32_t flags);</pre>
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<p>
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which takes identical arguments to <a href="../api_reference/C/dbcreate.html" class="olink">db_create()</a>.
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</p>
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<p>
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Otherwise the API is completely consistent with the standard
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Berkeley DB API.
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</p>
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<p>
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The mod_db4 module requires the Berkeley DB library be
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compiled with C++ extensions and the MM library. (The MM
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library provides an abstraction layer which allows related
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processes to share data easily. On systems where shared memory
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or other inter-process communication mechanisms are not
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available, the MM library emulates them using temporary files.
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MM is used in several operating systems to provide shared
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memory pools to Apache modules.)
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</p>
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<p>
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To build this apache module, perform the following
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steps:
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</p>
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<pre class="programlisting">% ./configure --with-apxs=[path to the apxs utility] \
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--with-db4=[Berkeley DB library installation directory] \
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--with-mm=[libmm installation directory]
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% make
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% make install</pre>
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<p>
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Post-installation, modules can use this extension via the
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functions documented in
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$APACHE_INCLUDEDIR/mod_db4_export.h.
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</p>
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</div>
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</div>
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<div class="navfooter">
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<hr />
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||
<table width="100%" summary="Navigation footer">
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<tr>
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<td width="40%" align="left"><a accesskey="p" href="tcl_faq.html">Prev</a> </td>
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<td width="20%" align="center"> </td>
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<td width="40%" align="right"> <a accesskey="n" href="ext_perl.html">Next</a></td>
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">Tcl FAQ </td>
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<td width="20%" align="center">
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<a accesskey="h" href="index.html">Home</a>
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</td>
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<td width="40%" align="right" valign="top"> Using Berkeley DB with Perl</td>
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</tr>
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</table>
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</div>
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</body>
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</html>
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