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<html><head><META http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><title>Apache Tomcat Configuration Reference - The Cluster Membership object</title><meta name="author" value="Filip Hanik"><meta name="email" value="fhanik@apache.org"></head><body bgcolor="#ffffff" text="#000000" link="#525D76" alink="#525D76" vlink="#525D76"><table border="0" width="100%" cellspacing="0"><!--PAGE HEADER--><tr><td><!--PROJECT LOGO--><a href="http://tomcat.apache.org/"><img src="../images/tomcat.gif" align="right" alt="
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The Apache Tomcat Servlet/JSP Container
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" border="0"></a></td><td><font face="arial,helvetica,sanserif"><h1>Apache Tomcat 6.0</h1></font></td><td><!--APACHE LOGO--><a href="http://www.apache.org/"><img src="../images/asf-logo.gif" align="right" alt="Apache Logo" border="0"></a></td></tr></table><table border="0" width="100%" cellspacing="4"><!--HEADER SEPARATOR--><tr><td colspan="2"><hr noshade="noshade" size="1"></td></tr><tr><!--LEFT SIDE NAVIGATION--><td width="20%" valign="top" nowrap="true"><p><strong>Links</strong></p><ul><li><a href="../index.html">Docs Home</a></li><li><a href="index.html">Config Ref. Home</a></li></ul><p><strong>Top Level Elements</strong></p><ul><li><a href="server.html">Server</a></li><li><a href="service.html">Service</a></li></ul><p><strong>Executors</strong></p><ul><li><a href="executor.html">Executor</a></li></ul><p><strong>Connectors</strong></p><ul><li><a href="http.html">HTTP</a></li><li><a href="ajp.html">AJP</a></li></ul><p><strong>Containers</strong></p><ul><li><a href="context.html">Context</a></li><li><a href="engine.html">Engine</a></li><li><a href="host.html">Host</a></li><li><a href="cluster.html">Cluster</a></li></ul><p><strong>Nested Components</strong></p><ul><li><a href="globalresources.html">Global Resources</a></li><li><a href="loader.html">Loader</a></li><li><a href="manager.html">Manager</a></li><li><a href="realm.html">Realm</a></li><li><a href="resources.html">Resources</a></li><li><a href="valve.html">Valve</a></li></ul><p><strong>Cluster Elements</strong></p><ul><li><a href="cluster.html">Cluster</a></li><li><a href="cluster-manager.html">Manager</a></li><li><a href="cluster-channel.html">Channel</a></li><li><a href="cluster-membership.html">Channel/Membership</a></li><li><a href="cluster-sender.html">Channel/Sender</a></li><li><a href="cluster-receiver.html">Channel/Receiver</a></li><li><a href="cluster-interceptor.html">Channel/Interceptor</a></li><li><a href="cluster-valve.html">Valve</a></li><li><a href="cluster-deployer.html">Deployer</a></li><li><a href="cluster-listener.html">ClusterListener</a></li></ul></td><!--RIGHT SIDE MAIN BODY--><td width="80%" valign="top" align="left"><table border="0" width="100%" cellspacing="4"><tr><td align="left" valign="top"><h1>Apache Tomcat Configuration Reference</h1><h2>The Cluster Membership object</h2></td><td align="right" valign="top" nowrap="true"><small><a href="printer/cluster-membership.html"><img src="../images/printer.gif" border="0" alt="Printer Friendly Version"><br>print-friendly<br>version
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</a></small></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Introduction"><strong>Introduction</strong></a></font></td></tr><tr><td><blockquote>
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<p>
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The membership component in the Apache Tribes <a href="cluster-channel.html">Channel</a> is responsible
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for dynamic discovery of other members(nodes) in the cluster.
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</p>
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</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Default Implementation"><strong>Default Implementation</strong></a></font></td></tr><tr><td><blockquote>
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<p>
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The default implementation of the cluster group notification is built on top of multicast heartbeats
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sent using UDP packets to a multicast IP address.
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Cluster members are grouped together by using the same multicast address/port combination.
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Each member sends out a heartbeat with a given interval (<code>frequency</code>), and this
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heartbeat is used for dynamic discovery.
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In a similar fashion, if a heartbeat has not been received in a timeframe specified by <code>dropTime</code>
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ms. a member is considered suspect and the channel and any membership listener will be notified.
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</p>
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</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Attributes"><strong>Attributes</strong></a></font></td></tr><tr><td><blockquote>
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<table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Multicast Attributes"><strong>Multicast Attributes</strong></a></font></td></tr><tr><td><blockquote>
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<table border="1" cellpadding="5"><tr><th width="15%" bgcolor="#023264"><font color="#ffffff">Attribute</font></th><th width="85%" bgcolor="#023264"><font color="#ffffff">Description</font></th></tr><tr><td align="left" valign="center"><strong><code>className</code></strong></td><td align="left" valign="center">
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<p>
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The default value is <code>org.apache.catalina.tribes.membership.McastService</code>
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and is currently the only implementation.
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This implementation uses multicast heartbeats for member discovery.
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</p>
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</td></tr><tr><td align="left" valign="center"><code>address</code></td><td align="left" valign="center">
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<p>
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The multicast address that the membership will broadcast its presence and listen
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for other heartbeats on. The default value is <code>228.0.0.4</code>
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Make sure your network is enabled for multicast traffic.<br>
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The multicast address, in conjunction with the <code>port</code> is what
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creates a cluster group. To divide up your farm into several different group, or to
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split up QA from production, change the <code>port</code> or the <code>address</code>
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<br>Previously known as mcastAddr.
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</p>
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</td></tr><tr><td align="left" valign="center"><code>port</code></td><td align="left" valign="center">
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<p>
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The multicast port, the default value is <code>45564</code><br>
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The multicast port, in conjunction with the <code>address</code> is what
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creates a cluster group. To divide up your farm into several different group, or to
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split up QA from production, change the <code>port</code> or the <code>address</code>
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</p>
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</td></tr><tr><td align="left" valign="center"><code>frequency</code></td><td align="left" valign="center">
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<p>
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The frequency in milliseconds in which heartbeats are sent out. The default value is <code>500</code> ms.<br>
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In most cases the default value is sufficient. Changing this value, simply changes the interval in between heartbeats.
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</p>
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</td></tr><tr><td align="left" valign="center"><code>dropTime</code></td><td align="left" valign="center">
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<p>
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The membership component will time out members and notify the Channel if a member fails to send a heartbeat within
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a give time. The default value is <code>3000</code> ms. This means, that if a heartbeat is not received from a
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member in that timeframe, the membership component will notify the cluster of this.<br>
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On a high latency network you may wish to increase this value, to protect against false positives.<br>
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Apache Tribes also provides a <a href="cluster-interceptor.html#tcpfailuredetector"><code>TcpFailureDetector</code></a> that will
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verify a timeout using a TCP connection when a heartbeat timeout has occurred. This protects against false positives.
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</p>
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</td></tr><tr><td align="left" valign="center"><code>bind</code></td><td align="left" valign="center">
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<p>
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Use this attribute if you wish to bind your multicast traffic to a specific network interface.
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By default, or when this attribute is unset, it tries to bind to <code>0.0.0.0</code> and sometimes on multihomed hosts
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this becomes a problem.
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</p>
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</td></tr><tr><td align="left" valign="center"><code>ttl</code></td><td align="left" valign="center">
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<p>
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The time-to-live setting for the multicast heartbeats.
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This setting should be a value between 0 and 255. The default value is VM implementation specific.
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</p>
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</td></tr><tr><td align="left" valign="center"><code>domain</code></td><td align="left" valign="center">
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<p>
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Apache Tribes has the ability to logically group members into domains, by using this domain attribute.
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The <code>org.apache.catalina.tribes.Member.getDomain()</code> method returns the value specified here.
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</p>
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</td></tr><tr><td align="left" valign="center"><code>soTimeout</code></td><td align="left" valign="center">
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<p>
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The sending and receiving of heartbeats is done on a single thread, hence to avoid blocking this thread forever,
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you can control the <code>SO_TIMEOUT</code> value on this socket.<br>
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If a value smaller or equal to 0 is presented, the code will default this value to frequency
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</p>
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</td></tr></table>
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</blockquote></td></tr></table>
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</blockquote></td></tr></table></td></tr><!--FOOTER SEPARATOR--><tr><td colspan="2"><hr noshade="noshade" size="1"></td></tr><!--PAGE FOOTER--><tr><td colspan="2"><div align="center"><font color="#525D76" size="-1"><em>
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Copyright © 1999-2006, Apache Software Foundation
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</em></font></div></td></tr></table></body></html>
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