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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 SessionIdGenerator Component</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 SessionIdGenerator Component</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="#Attributes">Attributes</a><ol><li><a href="#Common_Attributes">Common Attributes</a></li><li><a href="#Standard_Implementation">Standard Implementation</a></li></ol></li></ul> |
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| 6 | </div><h3 id="Introduction">Introduction</h3><div class="text"> |
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| 7 | |||
| 8 | <p>The <strong>SessionIdGenerator</strong> element represents the <em>session |
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| 9 | id generator</em> that will be used to create session ids used by |
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| 10 | web application HTTP sessions.</p> |
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| 11 | |||
| 12 | <p>A SessionIdGenerator element MAY be nested inside a |
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| 13 | <a href="manager.html">Manager</a> component. If it is not included, |
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| 14 | a default SessionIdGenerator configuration will be created automatically, which |
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| 15 | is sufficient for most requirements, — see |
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| 16 | <em>Standard SessionIdGenerator Implementation</em> below for the details |
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| 17 | of this configuration.</p> |
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| 18 | |||
| 19 | </div><h3 id="Attributes">Attributes</h3><div class="text"> |
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| 20 | |||
| 21 | <div class="subsection"><h4 id="Common_Attributes">Common Attributes</h4><div class="text"> |
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| 22 | |||
| 23 | <p>All implementations of <strong>SessionIdGenerator</strong> |
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| 24 | support the following attributes:</p> |
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| 25 | |||
| 26 | <table class="defaultTable"><tr><th style="width: 15%;"> |
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| 27 | Attribute |
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| 28 | </th><th style="width: 85%;"> |
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| 29 | Description |
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| 30 | </th></tr><tr id="Attributes_Common Attributes_className"><td><code class="attributeName">className</code></td><td> |
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| 31 | <p>Java class name of the implementation to use. This class must |
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| 32 | implement the <code>org.apache.catalina.SessionIdGenerator</code> interface. |
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| 33 | If not specified, the standard value (defined below) will be used.</p> |
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| 34 | </td></tr><tr id="Attributes_Common Attributes_jvmRoute"><td><code class="attributeName">jvmRoute</code></td><td> |
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| 35 | <p>A routing identifier for this Tomcat instance. It will be added |
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| 36 | to the session id to allow for stateless stickiness routing by |
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| 37 | load balancers. The details on how the <code>jvmRoute</code> |
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| 38 | will be included in the id are implementation dependent. |
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| 39 | See <a href="#Standard_Implementation">Standard Implementation</a> |
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| 40 | for the default behavior.</p> |
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| 41 | |||
| 42 | <p><strong>NOTE</strong> - The value for this property is inherited |
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| 43 | automatically from the <code>jvmRoute</code> attribute of the |
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| 44 | <a href="engine.html">Engine</a> element.</p> |
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| 45 | </td></tr><tr id="Attributes_Common Attributes_sessionIdLength"><td><code class="attributeName">sessionIdLength</code></td><td> |
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| 46 | <p>The length of session ids created by this SessionIdGenerator. |
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| 47 | The details on how the <code>sessionIdLength</code> |
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| 48 | influences the session id length are implementation dependent. |
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| 49 | See <a href="#Standard_Implementation">Standard Implementation</a> |
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| 50 | for the default behavior.</p> |
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| 51 | </td></tr></table> |
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| 52 | |||
| 53 | </div></div> |
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| 54 | |||
| 55 | |||
| 56 | <div class="subsection"><h4 id="Standard_Implementation">Standard Implementation</h4><div class="text"> |
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| 57 | |||
| 58 | <p>Tomcat provides a standard implementations of <strong>SessionIdGenerator</strong> |
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| 59 | for use.</p> |
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| 60 | |||
| 61 | <h3>Standard SessionIdGenerator Implementation</h3> |
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| 62 | |||
| 63 | <p>The standard implementation of <strong>SessionIdGenerator</strong> is |
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| 64 | <strong>org.apache.catalina.util.StandardSessionIdGenerator</strong>. |
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| 65 | It supports the following attributes:</p> |
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| 66 | |||
| 67 | <table class="defaultTable"><tr><th style="width: 15%;"> |
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| 68 | Attribute |
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| 69 | </th><th style="width: 85%;"> |
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| 70 | Description |
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| 71 | </th></tr><tr id="Attributes_Standard Implementation_jvmRoute"><td><code class="attributeName">jvmRoute</code></td><td> |
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| 72 | <p>A routing identifier for this Tomcat instance. It will be added |
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| 73 | to the end of the session id separated by a ".".</p> |
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| 74 | </td></tr><tr id="Attributes_Standard Implementation_sessionIdLength"><td><code class="attributeName">sessionIdLength</code></td><td> |
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| 75 | <p>The length of session ids created by this SessionIdGenerator. |
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| 76 | More precisely the session id length is twice the value of |
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| 77 | <code>sessionIdLength</code> plus the length of the trailing |
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| 78 | <code>jvmRoute</code> if given. The factor 2 is because |
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| 79 | the session id is constructed using <code>sessionIdLength</code> |
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| 80 | random bytes, each byte being encoded in two hex characters |
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| 81 | in the actual id. The default value is 16.</p> |
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| 82 | </td></tr></table> |
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| 83 | |||
| 84 | </div></div> |
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| 85 | |||
| 86 | |||
| 87 | </div></div></div></div></div><footer><div id="footer"> |
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| 88 | Copyright © 1999-2025, The Apache Software Foundation |
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| 89 | <br> |
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| 90 | Apache Tomcat, Tomcat, Apache, the Apache Tomcat logo and the Apache logo |
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| 91 | are either registered trademarks or trademarks of the Apache Software |
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| 92 | Foundation. |
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| 93 | </div></footer></div></body></html> |