| <html><head><META http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><title>Apache Tomcat Configuration Reference (6.0.39) - The Cluster Membership object</title><meta name="author" content="Filip Hanik"><style type="text/css" media="print"> | |
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| " border="0"></a></td><td><h1><font face="arial,helvetica,sanserif">Apache Tomcat 6.0</font></h1><font face="arial,helvetica,sanserif">Version 6.0.39, Jan 27 2014</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="nowrap" class="noPrint"><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="listeners.html">Listeners</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><p><strong>Other</strong></p><ul><li><a href="filter.html">Filter</a></li><li><a href="systemprops.html">System properties</a></li></ul></td><!--RIGHT SIDE MAIN BODY--><td width="80%" valign="top" align="left" id="mainBody"><h1>Apache Tomcat Configuration Reference</h1><h2>The Cluster Membership object</h2><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Table of Contents"><!--()--></a><a name="Table_of_Contents"><strong>Table of Contents</strong></a></font></td></tr><tr><td><blockquote> | |
| <ul><li><a href="#Introduction">Introduction</a></li><li><a href="#Default_Implementation">Default Implementation</a></li><li><a href="#Attributes">Attributes</a><ol><li><a href="#Multicast_Attributes">Multicast Attributes</a></li></ol></li></ul> | |
| </blockquote></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> | |
| <p> | |
| The membership component in the Apache Tribes <a href="cluster-channel.html">Channel</a> is responsible | |
| for dynamic discovery of other members(nodes) in the cluster. | |
| </p> | |
| </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"><!--()--></a><a name="Default_Implementation"><strong>Default Implementation</strong></a></font></td></tr><tr><td><blockquote> | |
| <p> | |
| The default implementation of the cluster group notification is built on top of multicast heartbeats | |
| sent using UDP packets to a multicast IP address. | |
| Cluster members are grouped together by using the same multicast address/port combination. | |
| Each member sends out a heartbeat with a given interval (<code>frequency</code>), and this | |
| heartbeat is used for dynamic discovery. | |
| In a similar fashion, if a heartbeat has not been received in a timeframe specified by <code>dropTime</code> | |
| ms. a member is considered suspect and the channel and any membership listener will be notified. | |
| </p> | |
| </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> | |
| <table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Multicast Attributes"><!--()--></a><a name="Multicast_Attributes"><strong>Multicast Attributes</strong></a></font></td></tr><tr><td><blockquote> | |
| <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"> | |
| <p> | |
| The default value is <code>org.apache.catalina.tribes.membership.McastService</code> | |
| and is currently the only implementation. | |
| This implementation uses multicast heartbeats for member discovery. | |
| </p> | |
| </td></tr><tr><td align="left" valign="center"><code>address</code></td><td align="left" valign="center"> | |
| <p> | |
| The multicast address that the membership will broadcast its presence and listen | |
| for other heartbeats on. The default value is <code>228.0.0.4</code> | |
| Make sure your network is enabled for multicast traffic.<br> | |
| The multicast address, in conjunction with the <code>port</code> is what | |
| creates a cluster group. To divide up your farm into several different group, or to | |
| split up QA from production, change the <code>port</code> or the <code>address</code> | |
| <br>Previously known as mcastAddr. | |
| </p> | |
| </td></tr><tr><td align="left" valign="center"><code>port</code></td><td align="left" valign="center"> | |
| <p> | |
| The multicast port, the default value is <code>45564</code><br> | |
| The multicast port, in conjunction with the <code>address</code> is what | |
| creates a cluster group. To divide up your farm into several different group, or to | |
| split up QA from production, change the <code>port</code> or the <code>address</code> | |
| </p> | |
| </td></tr><tr><td align="left" valign="center"><code>frequency</code></td><td align="left" valign="center"> | |
| <p> | |
| The frequency in milliseconds in which heartbeats are sent out. The default value is <code>500</code> ms.<br> | |
| In most cases the default value is sufficient. Changing this value, simply changes the interval in between heartbeats. | |
| </p> | |
| </td></tr><tr><td align="left" valign="center"><code>dropTime</code></td><td align="left" valign="center"> | |
| <p> | |
| The membership component will time out members and notify the Channel if a member fails to send a heartbeat within | |
| a give time. The default value is <code>3000</code> ms. This means, that if a heartbeat is not received from a | |
| member in that timeframe, the membership component will notify the cluster of this.<br> | |
| On a high latency network you may wish to increase this value, to protect against false positives.<br> | |
| Apache Tribes also provides a <a href="cluster-interceptor.html#tcpfailuredetector"><code>TcpFailureDetector</code></a> that will | |
| verify a timeout using a TCP connection when a heartbeat timeout has occurred. This protects against false positives. | |
| </p> | |
| </td></tr><tr><td align="left" valign="center"><code>bind</code></td><td align="left" valign="center"> | |
| <p> | |
| Use this attribute if you wish to bind your multicast traffic to a specific network interface. | |
| By default, or when this attribute is unset, it tries to bind to <code>0.0.0.0</code> and sometimes on multihomed hosts | |
| this becomes a problem. | |
| </p> | |
| </td></tr><tr><td align="left" valign="center"><code>ttl</code></td><td align="left" valign="center"> | |
| <p> | |
| The time-to-live setting for the multicast heartbeats. | |
| This setting should be a value between 0 and 255. The default value is VM implementation specific. | |
| </p> | |
| </td></tr><tr><td align="left" valign="center"><code>domain</code></td><td align="left" valign="center"> | |
| <p> | |
| Apache Tribes has the ability to logically group members into domains, by using this domain attribute. | |
| The <code>org.apache.catalina.tribes.Member.getDomain()</code> method returns the value specified here. | |
| </p> | |
| </td></tr><tr><td align="left" valign="center"><code>soTimeout</code></td><td align="left" valign="center"> | |
| <p> | |
| The sending and receiving of heartbeats is done on a single thread, hence to avoid blocking this thread forever, | |
| you can control the <code>SO_TIMEOUT</code> value on this socket.<br> | |
| If a value smaller or equal to 0 is presented, the code will default this value to frequency | |
| </p> | |
| </td></tr><tr><td align="left" valign="center"><code>recoveryEnabled</code></td><td align="left" valign="center"> | |
| <p> | |
| In case of a network failure, Java multicast socket don't transparently fail over, instead the socket will continuously | |
| throw IOException upon each receive request. When recoveryEnabled is set to true, this will close the multicast socket | |
| and open a new socket with the same properties as defined above.<br> | |
| The default is <code>true</code>. <br> | |
| </p> | |
| </td></tr><tr><td align="left" valign="center"><code>recoveryCounter</code></td><td align="left" valign="center"> | |
| <p> | |
| When <code>recoveryEnabled==true</code> this value indicates how many times we will try recovery. | |
| The default is <code>10</code>. <br> | |
| </p> | |
| </td></tr><tr><td align="left" valign="center"><code>recoverySleepTime</code></td><td align="left" valign="center"> | |
| <p> | |
| When <code>recoveryEnabled==true</code> this value indicates how long time (in milliseconds) | |
| the system will sleep in between recovery attempts, until we either recovered successfully or we have reached the | |
| recoveryCounter limit. | |
| The default is <code>5000</code> (5 seconds). <br> | |
| </p> | |
| </td></tr></table> | |
| </blockquote></td></tr></table> | |
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