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| 771 | blopes | 1 | <!DOCTYPE html SYSTEM "about:legacy-compat"> |
| 2 | <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 (9.0.112) - The Cluster Channel object</title></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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| 3 | Version 9.0.112, |
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| 4 | <time datetime="2025-11-06">Nov 6 2025</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="runtime-attributes.html">Runtime attributes</a></li><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 Channel object</h2><h3 id="Table_of_Contents">Table of Contents</h3><div class="text"> |
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| 5 | <ul><li><a href="#Introduction">Introduction</a></li><li><a href="#Nested_Components">Nested Components</a></li><li><a href="#Attributes">Attributes</a><ol><li><a href="#Common_Attributes">Common Attributes</a></li><li><a href="#org.apache.catalina.tribes.group.GroupChannel_Attributes">org.apache.catalina.tribes.group.GroupChannel Attributes</a></li></ol></li></ul> |
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| 6 | </div><h3 id="Introduction">Introduction</h3><div class="text"> |
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| 7 | The cluster channel is the main component of a small framework we've nicknamed Apache Tribes.<br> |
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| 8 | The channel manages a set of sub components and together they create a group communication framework.<br> |
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| 9 | This framework is then used internally by the components that need to send messages between different Tomcat instances. |
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| 10 | <br> |
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| 11 | A few examples of these components would be the SimpleTcpCluster that does the messaging for the DeltaManager, |
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| 12 | or the BackupManager that uses a different replication strategy. The ReplicatedContext object does also |
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| 13 | use the channel object to communicate context attribute changes. |
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| 14 | </div><h3 id="Nested_Components">Nested Components</h3><div class="text"> |
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| 15 | <p><b><a href="cluster-membership.html">Channel/Membership</a>:</b> <br> |
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| 16 | The Membership component is responsible for auto discovering new nodes in the cluster |
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| 17 | and also to provide for notifications for any nodes that have not responded with a heartbeat. |
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| 18 | The default implementation uses multicast.<br> |
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| 19 | In the membership component you configure how your nodes, aka. members, are to be discovered and/or |
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| 20 | divided up. |
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| 21 | You can always find out more about <a href="../tribes/introduction.html">Apache Tribes</a> |
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| 22 | </p> |
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| 23 | <p><b><a href="cluster-sender.html">Channel/Sender</a>:</b> <br> |
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| 24 | The Sender component manages all outbound connections and data messages that are sent |
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| 25 | over the network from one node to another. |
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| 26 | This component allows messages to be sent in parallel. |
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| 27 | The default implementation uses TCP client sockets, and socket tuning for outgoing messages are |
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| 28 | configured here.<br> |
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| 29 | You can always find out more about <a href="../tribes/introduction.html">Apache Tribes</a> |
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| 30 | </p> |
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| 31 | <p><b><a href="cluster-sender.html#transport">Channel/Sender/Transport</a>:</b> <br> |
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| 32 | The Transport component is the bottom IO layer for the sender component. |
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| 33 | The default implementation uses non-blocking TCP client sockets.<br> |
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| 34 | You can always find out more about <a href="../tribes/introduction.html">Apache Tribes</a> |
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| 35 | </p> |
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| 36 | <p><b><a href="cluster-receiver.html">Channel/Receiver</a>:</b> <br> |
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| 37 | The receiver component listens for messages from other nodes. |
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| 38 | Here you will configure the cluster thread pool, as it will dispatch incoming |
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| 39 | messages to a thread pool for faster processing. |
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| 40 | The default implementation uses non-blocking TCP server sockets.<br> |
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| 41 | You can always find out more about <a href="../tribes/introduction.html">Apache Tribes</a> |
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| 42 | </p> |
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| 43 | <p><b><a href="cluster-interceptor.html">Channel/Interceptor</a>:</b> <br> |
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| 44 | The channel will send messages through an interceptor stack. Because of this, you have the ability to |
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| 45 | customize the way messages are sent and received, and even how membership is handled.<br> |
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| 46 | You can always find out more about <a href="../tribes/introduction.html">Apache Tribes</a> |
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| 47 | </p> |
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| 48 | </div><h3 id="Attributes">Attributes</h3><div class="text"> |
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| 49 | |||
| 50 | <div class="subsection"><h4 id="Common_Attributes">Common Attributes</h4><div class="text"> |
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| 51 | |||
| 52 | <table class="defaultTable"><tr><th style="width: 15%;"> |
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| 53 | Attribute |
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| 54 | </th><th style="width: 85%;"> |
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| 55 | Description |
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| 56 | </th></tr><tr id="Attributes_Common Attributes_className"><td><strong><code class="attributeName">className</code></strong></td><td> |
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| 57 | The default value here is <code>org.apache.catalina.tribes.group.GroupChannel</code> and is |
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| 58 | currently the only implementation available. |
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| 59 | </td></tr></table> |
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| 60 | |||
| 61 | |||
| 62 | </div></div> |
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| 63 | |||
| 64 | <div class="subsection"><h4 id="org.apache.catalina.tribes.group.GroupChannel_Attributes">org.apache.catalina.tribes.group.GroupChannel Attributes</h4><div class="text"> |
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| 65 | |||
| 66 | <table class="defaultTable"><tr><th style="width: 15%;"> |
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| 67 | Attribute |
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| 68 | </th><th style="width: 85%;"> |
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| 69 | Description |
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| 70 | </th></tr><tr id="Attributes_org.apache.catalina.tribes.group.GroupChannel Attributes_heartbeat"><td><code class="attributeName">heartbeat</code></td><td> |
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| 71 | Flag whether the channel manages its own heartbeat. |
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| 72 | If set to true, the channel start a local thread for the heart beat. |
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| 73 | If set this flag to false, you must set SimpleTcpCluster#heartbeatBackgroundEnabled |
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| 74 | to true. default value is true. |
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| 75 | </td></tr><tr id="Attributes_org.apache.catalina.tribes.group.GroupChannel Attributes_heartbeatSleeptime"><td><code class="attributeName">heartbeatSleeptime</code></td><td> |
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| 76 | If heartbeat == true, specifies the interval of heartbeat thread in milliseconds. |
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| 77 | The default is 5000 (5 seconds). |
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| 78 | </td></tr><tr id="Attributes_org.apache.catalina.tribes.group.GroupChannel Attributes_optionCheck"><td><code class="attributeName">optionCheck</code></td><td> |
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| 79 | If set to true, the GroupChannel will check the option flags that each |
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| 80 | interceptor is using. Reports an error if two interceptor share the same |
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| 81 | flag. The default is false. |
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| 82 | </td></tr><tr id="Attributes_org.apache.catalina.tribes.group.GroupChannel Attributes_jmxEnabled"><td><code class="attributeName">jmxEnabled</code></td><td> |
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| 83 | Flag whether the channel components register with JMX or not. |
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| 84 | The default value is true. |
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| 85 | </td></tr><tr id="Attributes_org.apache.catalina.tribes.group.GroupChannel Attributes_jmxDomain"><td><code class="attributeName">jmxDomain</code></td><td> |
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| 86 | if <code>jmxEnabled</code> set to true, specifies the jmx domain which |
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| 87 | this channel should be registered. The ClusterChannel is used as the |
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| 88 | default value. |
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| 89 | </td></tr><tr id="Attributes_org.apache.catalina.tribes.group.GroupChannel Attributes_jmxPrefix"><td><code class="attributeName">jmxPrefix</code></td><td> |
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| 90 | if <code>jmxEnabled</code> set to true, specifies the jmx prefix which |
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| 91 | will be used with channel ObjectName. |
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| 92 | </td></tr></table> |
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| 93 | |||
| 94 | </div></div> |
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| 95 | |||
| 96 | </div></div></div></div></div><footer><div id="footer"> |
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| 97 | Copyright © 1999-2025, The Apache Software Foundation |
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| 98 | <br> |
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| 99 | Apache Tomcat, Tomcat, Apache, the Apache Tomcat logo and the Apache logo |
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| 100 | are either registered trademarks or trademarks of the Apache Software |
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| 101 | Foundation. |
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| 102 | </div></footer></div></body></html> |