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208 lines
8.1 KiB
208 lines
8.1 KiB
<?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 5. Configuring for Write Forwarding</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="Getting Started with Replicated Berkeley DB Applications" />
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<link rel="up" href="index.html" title="Getting Started with Replicated Berkeley DB Applications" />
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<link rel="prev" href="exampledoloop.html" title="Example Processing Loop" />
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<link rel="next" href="wrfor_programlisting.html" title="Program Listing" />
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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 12.1.6.2</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 5. Configuring for Write Forwarding</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="exampledoloop.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="wrfor_programlisting.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="writeforwarding"></a>Chapter 5. Configuring for Write Forwarding</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="writeforwarding.html#wrforapp_overview">Application with Write Forwarding Overview</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="wrfor_programlisting.html">Program Listing</a>
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</span>
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</dt>
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<dd>
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<dl>
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<dt>
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<span class="sect2">
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<a href="wrfor_programlisting.html#repwrforconfiginfo_cxx">
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<span>Class: RepConfigInfo</span>
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</a>
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</span>
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</dt>
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<dt>
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<span class="sect2">
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<a href="wrfor_programlisting.html#repwrformgr_cxx">Class: excxx_repquote_gsg_RepMgrWrforGSG</a>
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</span>
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</dt>
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<dt>
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<span class="sect2">
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<a href="wrfor_programlisting.html#wrforusage_cxx">Function: usage()</a>
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</span>
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</dt>
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<dt>
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<span class="sect2">
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<a href="wrfor_programlisting.html#wrformain_cxx">Function: main()</a>
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</span>
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</dt>
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<dt>
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<span class="sect2">
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<a href="wrfor_programlisting.html#wrfor_init_cxx">Method: RepMgrWrforGSG::init()</a>
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</span>
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</dt>
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<dt>
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<span class="sect2">
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<a href="wrfor_programlisting.html#doloop_wrforcxx">Method: RepMgrWrforGSG::doloop()</a>
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</span>
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</dt>
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<dt>
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<span class="sect2">
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<a href="wrfor_programlisting.html#wrfor_printstocks_c">
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<span>Method: RepMgrWrforGSG::print_stocks()</span>
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</a>
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</span>
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</dt>
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</dl>
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</dd>
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</dl>
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</div>
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<p>
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By default, write operations cannot be performed on a replication
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client site. Replication Manager provides automatic write forwarding
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as a configurable option for applications with simple data and
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transaction models. (See the
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<a href="../../programmer_reference/comm_repsites.html#conf_writeforw" class="olink">Configuring for Write Forwarding</a>
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section in the <em class="citetitle">Berkeley DB Programmer's Reference Guide</em> for more information.)
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</p>
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<p>
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In this chapter, we configure write forwarding for the simple
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transaction-protected DB application that you created in
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the <a class="xref" href="txnapp.html" title="Chapter 2. Transactional Application">Transactional Application</a> chapter.
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</p>
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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="wrforapp_overview"></a>Application with Write Forwarding Overview</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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Write forwarding simplifies adding replication to the stock
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market quotes database application. Once write forwarding is
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configured, this application allows any site to accept stock quote
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updates. There is no need to confine write operations to the
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master or even to know which site is the master.
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</p>
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<p>
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The application operates by presenting you with a command line
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prompt. You then enter the stock symbol and its value, separated by
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a space. The application takes this information and writes it to the
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database.
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</p>
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<p>
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To see the contents of the database, simply press
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<code class="literal">return</code> at the command prompt.
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</p>
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<p>
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To quit the application, type 'quit' or 'exit' at the command
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prompt.
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</p>
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<p>
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For example, the following illustrates the application's usage.
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In it, we use entirely fictitious stock market symbols and price
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values.
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</p>
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<pre class="programlisting">node01> ./excxx_repquote_gsg_RepMgrWrforGSG -h env_home_dir -L node01:5000
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QUOTESERVER> stock1 88
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QUOTESERVER> stock2 .08
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QUOTESERVER>
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Symbol Price
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====== =====
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stock1 88
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stock2 .08 </pre>
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<p>
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where <code class="literal">L</code> is used to identify the local site
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as group creator, which creates the database and starts
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this site as master.
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</p>
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<p>
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With write forwarding, we can add a new stock value in the client
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site. In the client site (node02), specify the new
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local client site and the existing remote site in the replication group.
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</p>
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<pre class="programlisting">node02> ./excxx_repquote_gsg_RepMgrWrforGSG -l node02:5001 -r node01:5000
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QUOTESERVER> stock3 99
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QUOTESERVER>
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Symbol Price
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====== =====
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stock1 88
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stock2 .08
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stock3 99
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QUOTESERVER> quit </pre>
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<p>
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Finally, verify that the <code class="literal">stock3</code> value replicated
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to the master:
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</p>
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<pre class="programlisting">QUOTESERVER>
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Symbol Price
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====== =====
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stock1 88
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stock2 .08
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stock3 99
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QUOTESERVER> quit </pre>
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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="exampledoloop.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="wrfor_programlisting.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">Example Processing Loop </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"> Program Listing</td>
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