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127 lines
6.3 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 6. Replication Examples</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 Berkeley DB, Java Edition High Availability Applications" />
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<link rel="prev" href="events.html" title="Listening for Events" />
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<link rel="next" href="administration.html" title="Chapter 7. Administration" />
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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 12.2.7.5</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 6. Replication Examples</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="events.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="administration.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="repexample"></a>Chapter 6. Replication Examples</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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JE HA provides three different example programs that illustrate
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the concepts discussed in this manual. You can find them in your
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JE distribution in the
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<code class="literal"><JE HOME>/examples/je/rep/quote</code> directory,
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where <JE HOME> is the directory where you
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installed your JE distribution.
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</p>
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<p>
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The examples provided for you are each based on a mock stock ticker
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application which stores stock values in a replicated JE
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environment. The differences in the three examples have to do with
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how each example handles requests for database access; in
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particular, database write requests.
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</p>
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<p>
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Briefly, each of the examples are:
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</p>
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<div class="itemizedlist">
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<ul type="disc">
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<li>
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<p>
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<a class="ulink" href="../examples/je/rep/quote/StockQuotes.html" target="_top">StockQuotes</a>: Illustrates the most basic demonstration of
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a replicated application. It is intended to help you gain
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an understanding of basic HA concepts. It demonstrates use
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of the HA APIs to create a replicated environment and issue
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read and write transactions.
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</p>
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<p>
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For this example, no attempt is made to route or forward
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write requests. Instead, the application blindly attempts
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any write requests that are made at the node. If the node
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is in the Replica state, a <a class="ulink" href="../java/com/sleepycat/je/rep/ReplicaWriteException.html" target="_top">ReplicaWriteException</a> is
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raised by the underlying HA code. The example then informs
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you of the problem by way of rejecting the operation.
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</p>
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</li>
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<li>
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<p>
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<a class="ulink" href="../examples/je/rep/quote/RouterDrivenStockQuotes.html" target="_top">RouterDrivenStockQuotes</a> and <a class="ulink" href="../examples/je/rep/quote/HARouter.html" target="_top">HARouter</a>: Illustrates
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how a software load balancer might be integrated with
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JE HA, where <a class="ulink" href="../examples/je/rep/quote/HARouter.html" target="_top">HARouter</a> plays the role of the load
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balancer for purposes of the example. It does this by
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using the <a class="ulink" href="../java/com/sleepycat/je/rep/monitor/Monitor.html" target="_top">Monitor</a> class to direct application
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requests to the appropriate node. Read-only requests
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are sent to Replicas, while read-write requests are sent
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to the replication group's Master.
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</p>
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</li>
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<li>
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<p>
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<a class="ulink" href="../examples/je/rep/quote/UpdateForwardingStockQuotes.html" target="_top">UpdateForwardingStockQuotes</a> and <a class="ulink" href="../examples/je/rep/quote/SimpleRouter.html" target="_top">SimpleRouter</a>:
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Illustrates the use of an HA unaware router that load
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balances read and write requests across the nodes in a
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replication group. The router is implemented in
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<a class="ulink" href="../examples/je/rep/quote/SimpleRouter.html" target="_top">SimpleRouter</a>, and is meant to illustrate how a load
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balancer appliance might fit into the JE HA
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architecture.
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</p>
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<p>
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This example is based on <a class="ulink" href="../examples/je/rep/quote/RouterDrivenStockQuotes.html" target="_top">RouterDrivenStockQuotes</a>.
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</p>
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</li>
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</ul>
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</div>
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<p>
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Usage of each of these examples is described in the Javadoc page
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for each example.
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</p>
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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="events.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="administration.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">Listening for Events </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"> Chapter 7. Administration</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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