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diff --git a/content/xdocs/Reliability Requirements.html b/content/xdocs/Reliability Requirements.html deleted file mode 100755 index 9cdf026009..0000000000 --- a/content/xdocs/Reliability Requirements.html +++ /dev/null @@ -1,96 +0,0 @@ -<html> - <head> - <title>Apache Qpid : Reliability Requirements</title> - <link rel="stylesheet" href="styles/site.css" type="text/css" /> - <META http-equiv="Content-Type" content="text/html; charset=UTF-8"> - </head> - - <body> - <table class="pagecontent" border="0" cellpadding="0" cellspacing="0" width="100%" bgcolor="#ffffff"> - <tr> - <td valign="top" class="pagebody"> - <div class="pageheader"> - <span class="pagetitle"> - Apache Qpid : Reliability Requirements - </span> - </div> - <div class="pagesubheading"> - This page last changed on Jun 11, 2007 by <font color="#0050B2">aconway</font>. - </div> - - <h1><a name="ReliabilityRequirements-ReliabilityRequirements"></a>Reliability Requirements</h1> - - -<h2><a name="ReliabilityRequirements-Failover%28sessionstate%29"></a>Fail-over (session state)</h2> - -<p>A cluster member informs its clients of backup candidates for each session. It can update the list periodically.</p> - -<p>After an unexpected disconnect the client can connect to one of the candidates and resume its session transparently. All session state is preserved including:</p> -<ul> - <li>Open references</li> - <li>Active consumers</li> - <li>Commands-in-flight</li> - <li>Open transactions (question: Is there any value in fail-over that aborts TX and/or DTX transactions?)</li> -</ul> - - -<p>Sessions <em>do not</em> survive</p> -<ul> - <li>multiple failures that include the current node and all back-up nodes for that session.</li> - <li>shutdown/restart of the cluster.</li> -</ul> - - -<h2><a name="ReliabilityRequirements-ClusterRestart%28durableresources%29"></a>Cluster Restart (durable resources)</h2> - -<p>The AMQP entities that survive a restart are those defined by AMQP to survive broker restart. AMQP defines <em>durable</em> exchanges and queues and <em>persistent</em> messages. Some further definitions:</p> -<ul> - <li><em>durable</em> message: persistent messages on a durable queues.</li> - <li><em>durable</em> enque: act of enqueuing a persistent message on a durable queue.</li> - <li><em>durable</em> binding: binding between durable exchange and durable queue.</li> -</ul> - - -<p>The following are preserved if the entire cluster shuts down/crashes and is re-started:</p> -<ul> - <li><em>Durable</em> wiring: durable exchanges, queues and bindings.</li> - <li><em>Durable</em> messages</li> - <li><em>Prepared</em> DTX transactions</li> -</ul> - - -<p>The following do not survive a restart:</p> -<ul> - <li>Session state</li> - <li>Non-durable wiring</li> - <li>TX transactions are aborted.</li> - <li>Unprepared DTX transactions are aborted.</li> - <li>Non-durable effects of prepared DTX transactions are lost.</li> -</ul> - - -<h3><a name="ReliabilityRequirements-RestartingDTXTransactions"></a>Restarting DTX Transactions</h3> - -<p>On restart, prepared DTX transactions may commit or rollback. In either case the outcome is <em>as if</em> the transaction had comitted or rolled back just <em>before</em> the restart: All durable transaction effects survive the restart, all non-durable effects are lost.</p> - -<p>In particular</p> -<ul> - <li>On <b><em>commit</em></b><b>:</b> <em>non durable</em> messages enqueued in the transaction are <em>lost</em>, as if they had been enqueued before the restart and were lost in the restart.</li> - <li>On <b><em>rollback:</em></b> <em>non durable</em> messages dequeued in the transaction are <em>lost</em>, as if they had been put back on the queue before restart and then lost in the restart.</li> -</ul> - - - - </td> - </tr> - </table> - <table border="0" cellpadding="0" cellspacing="0" width="100%"> - <tr> - <td height="12" background="border/border_bottom.gif"><img src="border/spacer.gif" width="1" height="1" border="0"/></td> - </tr> - <tr> - <td align="center"><font color="grey">Document generated by Confluence on Apr 22, 2008 02:47</font></td> - </tr> - </table> - </body> -</html>
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