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276 lines
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<!DOCTYPE html SYSTEM "about:legacy-compat">
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<html lang="en"><head><META http-equiv="Content-Type" content="text/html; charset=UTF-8"><link href="../images/docs-stylesheet.css" rel="stylesheet" type="text/css"><title>Apache Tomcat 9 Configuration Reference (9.0.76) - The Cluster Membership object</title><meta name="author" content="Filip Hanik"></head><body><div id="wrapper"><header><div id="header"><div><div><div class="logo noPrint"><a href="https://tomcat.apache.org/"><img alt="Tomcat Home" src="../images/tomcat.png"></a></div><div style="height: 1px;"></div><div class="asfLogo noPrint"><a href="https://www.apache.org/" target="_blank"><img src="../images/asf-logo.svg" alt="The Apache Software Foundation" style="width: 266px; height: 83px;"></a></div><h1>Apache Tomcat 9 Configuration Reference</h1><div class="versionInfo">
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Version 9.0.76,
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<time datetime="2023-06-05">Jun 5 2023</time></div><div style="height: 1px;"></div><div style="clear: left;"></div></div></div></div></header><div id="middle"><div><div id="mainLeft" class="noprint"><div><nav><div><h2>Links</h2><ul><li><a href="../index.html">Docs Home</a></li><li><a href="index.html">Config Ref. Home</a></li><li><a href="https://cwiki.apache.org/confluence/display/TOMCAT/FAQ">FAQ</a></li><li><a href="#comments_section">User Comments</a></li></ul></div><div><h2>Top Level Elements</h2><ul><li><a href="server.html">Server</a></li><li><a href="service.html">Service</a></li></ul></div><div><h2>Executors</h2><ul><li><a href="executor.html">Executor</a></li></ul></div><div><h2>Connectors</h2><ul><li><a href="http.html">HTTP/1.1</a></li><li><a href="http2.html">HTTP/2</a></li><li><a href="ajp.html">AJP</a></li></ul></div><div><h2>Containers</h2><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></div><div><h2>Nested Components</h2><ul><li><a href="cookie-processor.html">CookieProcessor</a></li><li><a href="credentialhandler.html">CredentialHandler</a></li><li><a href="globalresources.html">Global Resources</a></li><li><a href="jar-scanner.html">JarScanner</a></li><li><a href="jar-scan-filter.html">JarScanFilter</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="sessionidgenerator.html">SessionIdGenerator</a></li><li><a href="valve.html">Valve</a></li></ul></div><div><h2>Cluster Elements</h2><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></div><div><h2>web.xml</h2><ul><li><a href="filter.html">Filter</a></li></ul></div><div><h2>Other</h2><ul><li><a href="systemprops.html">System properties</a></li><li><a href="jaspic.html">JASPIC</a></li></ul></div></nav></div></div><div id="mainRight"><div id="content"><h2>The Cluster Membership object</h2><h3 id="Table_of_Contents">Table of Contents</h3><div class="text">
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<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="#Common_Attributes">Common Attributes</a></li><li><a href="#Multicast_Attributes">Multicast Attributes</a></li><li><a href="#Static_Membership_Attributes">Static Membership Attributes</a></li></ol></li><li><a href="#Nested_Components">Nested Components</a><ol><li><a href="#StaticMember_Attributes">StaticMember Attributes</a></li><li><a href="#Setting">Setting</a></li></ol></li></ul>
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</div><h3 id="Introduction">Introduction</h3><div class="text">
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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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There are currently two different membership service, the <code>org.apache.catalina.tribes.membership.McastService</code>
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and the <code>org.apache.catalina.tribes.membership.StaticMembershipService</code>.
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The <code>McastService</code> builds a multicast based membership service
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that sends UDP packets to multicast IP addresses.
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The <code>StaticMembershipService</code> builds a unicast based membership
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service that sends TCP packets to predefined member address.
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</p>
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</div><h3 id="Default_Implementation">Default Implementation</h3><div class="text">
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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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</div><h3 id="Attributes">Attributes</h3><div class="text">
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<div class="subsection"><h4 id="Common_Attributes">Common Attributes</h4><div class="text">
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<table class="defaultTable"><tr><th style="width: 15%;">
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Attribute
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</th><th style="width: 85%;">
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Description
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</th></tr><tr><td><strong><code class="attributeName">className</code></strong></td><td>
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<p>
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The implementation of the membership component.
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Two implementations available, <code>org.apache.catalina.tribes.membership.McastService</code>
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and <code>org.apache.catalina.tribes.membership.StaticMembershipService</code>.
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</p>
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</td></tr></table>
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</div></div>
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<div class="subsection"><h4 id="Multicast_Attributes">Multicast Attributes</h4><div class="text">
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<table class="defaultTable"><tr><th style="width: 15%;">
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Attribute
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</th><th style="width: 85%;">
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Description
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</th></tr><tr><td><strong><code class="attributeName">className</code></strong></td><td>
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<p>
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The value is <code>org.apache.catalina.tribes.membership.McastService</code>.
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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><code class="attributeName">address</code></td><td>
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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><code class="attributeName">port</code></td><td>
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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><code class="attributeName">frequency</code></td><td>
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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><code class="attributeName">dropTime</code></td><td>
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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#org.apache.catalina.tribes.group.interceptors.TcpFailureDetector_Attributes"><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><code class="attributeName">bind</code></td><td>
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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><code class="attributeName">ttl</code></td><td>
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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><code class="attributeName">domain</code></td><td>
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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><code class="attributeName">soTimeout</code></td><td>
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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><tr><td><code class="attributeName">recoveryEnabled</code></td><td>
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<p>
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In case of a network failure, Java multicast socket don't transparently fail over, instead the socket will continuously
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throw IOException upon each receive request. When recoveryEnabled is set to true, this will close the multicast socket
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and open a new socket with the same properties as defined above.<br>
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The default is <code>true</code>. <br>
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</p>
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</td></tr><tr><td><code class="attributeName">recoveryCounter</code></td><td>
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<p>
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When <code>recoveryEnabled==true</code> this value indicates how many
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times an error has to occur before recovery is attempted. The default is
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<code>10</code>. <br>
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</p>
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</td></tr><tr><td><code class="attributeName">recoverySleepTime</code></td><td>
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<p>
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When <code>recoveryEnabled==true</code> this value indicates how long time (in milliseconds)
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the system will sleep in between recovery attempts, until it recovers successfully.
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The default is <code>5000</code> (5 seconds). <br>
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</p>
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</td></tr><tr><td><code class="attributeName">localLoopbackDisabled</code></td><td>
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<p>
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Membership uses multicast, it will call <code>java.net.MulticastSocket.setLoopbackMode(localLoopbackDisabled)</code>.
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When <code>localLoopbackDisabled==true</code> multicast messages will not reach other nodes on the same local machine.
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The default is <code>false</code>. <br>
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</p>
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</td></tr></table>
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</div></div>
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<div class="subsection"><h4 id="Static_Membership_Attributes">Static Membership Attributes</h4><div class="text">
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<p>When using the static membership service you must ensure that the
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<code>channelStartOptions</code> attribute of the <code>Cluster</code>
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element is set to the default value of <code>15</code>.</p>
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<table class="defaultTable"><tr><th style="width: 15%;">
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Attribute
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</th><th style="width: 85%;">
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Description
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</th></tr><tr><td><strong><code class="attributeName">className</code></strong></td><td>
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<p>
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The value is <code>org.apache.catalina.tribes.membership.StaticMembershipService</code>.
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</p>
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</td></tr><tr><td><code class="attributeName">connectTimeout</code></td><td>
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<p>
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Timeout for attempting a TCP connection to address of predefined static member.
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Default is <code>500</code> ms.
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</p>
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</td></tr><tr><td><code class="attributeName">expirationTime</code></td><td>
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<p>
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If members have failed to update their alive time within the given time,
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this membership will notify the memberDisappeared event to cluster.
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Default is <code>5000</code> ms.
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</p>
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</td></tr><tr><td><code class="attributeName">rpcTimeout</code></td><td>
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<p>
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Timeout for messages that used for member notification to/from othee nodes.
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Default is <code>3000</code> ms.
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</p>
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</td></tr><tr><td><code class="attributeName">useThread</code></td><td>
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<p>
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If set to true, this membership service will start a local thread for
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sending a ping message. if set to <code>false</code>, channel heartbeat
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will send a ping message. Default is <code>false</code>.
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</p>
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</td></tr><tr><td><code class="attributeName">pingInterval</code></td><td>
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<p>
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If <code>useThread</code> == <code>true</code>, defines the interval of
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sending a ping message. Default is <code>1000</code> ms.
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</p>
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</td></tr></table>
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</div></div>
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</div><h3 id="Nested_Components">Nested Components</h3><div class="text">
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<p>
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Static Membership Service allows nesting of a <strong><LocalMember></strong>
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and <strong><Member></strong> element.
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</p>
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<div class="subsection"><h4 id="StaticMember_Attributes">StaticMember Attributes</h4><div class="text">
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<p><b>LocalMember:</b> <br>
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Static member that is the local member of the static cluster group.
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</p>
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<p><strong>Note:</strong> In Tomcat 9.0.17 and later, The setting of local member is not required.
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It is possible to set up a list of all cluster members including local member instead of setting this components.
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</p>
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<table class="defaultTable"><tr><th style="width: 15%;">
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Attribute
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</th><th style="width: 85%;">
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Description
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</th></tr><tr><td><strong><code class="attributeName">className</code></strong></td><td>
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Only one implementation available:<code>org.apache.catalina.tribes.membership.StaticMember</code>
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</td></tr><tr><td><code class="attributeName">port</code></td><td>
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There is no need to set.
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The value of this attribute inherits from the cluster receiver setting.
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</td></tr><tr><td><code class="attributeName">securePort</code></td><td>
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There is no need to set.
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The value of this attribute inherits from the cluster receiver setting.
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</td></tr><tr><td><code class="attributeName">host</code></td><td>
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There is no need to set.
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The value of this attribute inherits from the cluster receiver setting.
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</td></tr><tr><td><code class="attributeName">domain</code></td><td>
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The logical cluster domain for that this static member listens for cluster messages.
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Two different type of values are possible:<br>
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1. Regular string values like "staging-domain" or "tomcat-cluster" will be converted into bytes
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using ISO-8859-1 encoding.
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2. byte array in string form, for example {216,123,12,3}<br>
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</td></tr><tr><td><strong><code class="attributeName">uniqueId</code></strong></td><td>
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A universally uniqueId for this static member.
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The values must be 16 bytes in the following form:<br>
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1. byte array in string form, for example {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15}<br>
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</td></tr></table>
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<p><b>Member:</b> <br>
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Static member that add to the static cluster group.
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</p>
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<table class="defaultTable"><tr><th style="width: 15%;">
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Attribute
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</th><th style="width: 85%;">
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Description
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</th></tr><tr><td><strong><code class="attributeName">className</code></strong></td><td>
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Only one implementation available:<code>org.apache.catalina.tribes.membership.StaticMember</code>
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</td></tr><tr><td><strong><code class="attributeName">port</code></strong></td><td>
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The port that this static member listens to for cluster messages
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</td></tr><tr><td><code class="attributeName">securePort</code></td><td>
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The secure port this static member listens to for encrypted cluster messages
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default value is <code>-1</code>, this value means the member is not listening on a secure port
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</td></tr><tr><td><strong><code class="attributeName">host</code></strong></td><td>
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The host (or network interface) that this static member listens for cluster messages.
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Three different type of values are possible:<br>
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1. IP address in the form of "216.123.1.23"<br>
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2. Hostnames like "tomcat01.mydomain.com" or "tomcat01" as long as they resolve correctly<br>
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3. byte array in string form, for example {216,123,12,3}<br>
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</td></tr><tr><td><code class="attributeName">domain</code></td><td>
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The logical cluster domain for that this static member listens for cluster messages.
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Two different type of values are possible:<br>
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1. Regular string values like "staging-domain" or "tomcat-cluster" will be converted into bytes
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using ISO-8859-1 encoding.<br>
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2. byte array in string form, for example {216,123,12,3}<br>
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</td></tr><tr><td><strong><code class="attributeName">uniqueId</code></strong></td><td>
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A universally uniqueId for this static member.
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The values must be 16 bytes in the following form:<br>
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1. byte array in string form, for example {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15}<br>
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</td></tr></table>
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</div></div>
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<div class="subsection"><h4 id="Setting">Setting</h4><div class="text">
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<p><b>Before Tomcat 9.0.16</b> <br>
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<div class="codeBox"><pre><code> <Membership className="org.apache.catalina.tribes.membership.StaticMembershipService">
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<LocalMember className="org.apache.catalina.tribes.membership.StaticMember"
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uniqueId="{0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15}"/>
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<Member className="org.apache.catalina.tribes.membership.StaticMember"
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port="4004"
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host="tomcat02.mydomain.com"
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uniqueId="{1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,1}"/>
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</Membership></code></pre></div>
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</p>
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<p><b>Tomcat9.0.17 and later</b> <br>
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<div class="codeBox"><pre><code> <Membership className="org.apache.catalina.tribes.membership.StaticMembershipService">
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<Member className="org.apache.catalina.tribes.membership.StaticMember"
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port="4004"
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host="tomcat01.mydomain.com"
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uniqueId="{0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15}"/>
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<Member className="org.apache.catalina.tribes.membership.StaticMember"
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port="4004"
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host="tomcat02.mydomain.com"
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uniqueId="{1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,1}"/>
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</Membership></code></pre></div>
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</p>
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</div></div>
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</div></div></div></div></div><footer><div id="footer">
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