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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 (9.0.112) - Overview
</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">
Version 9.0.112,
<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>Overview
</h2><h3 id="Overview">Overview
</h3><div class="text">
<p>This manual contains reference information about all of the configuration
directives that can be included in a
<code>conf/server.xml
</code> file to
configure the behavior of the Tomcat Servlet/JSP container. It does not
attempt to describe which configuration directives should be used to perform
specific tasks - for that, see the various
<em>How-To
</em> documents on the
main index page.
</p>
<p>Tomcat configuration files are formatted as schemaless XML; elements and
attributes are case-sensitive. Apache Ant-style variable substitution
is supported; a system property with the name
<code>propname
</code> may be
used in a configuration file using the syntax
<code>${propname}
</code>. All
system properties are available including those set using the
<code>-D
</code>
syntax, those automatically made available by the JVM and those configured in
the
<code>$CATALINA_BASE/conf/catalina.properties
</code> file.
</p>
<p>The configuration element descriptions are organized into the following
major categories:
</p>
<ul>
<li><strong>Top Level Elements
</strong> -
<code><Server
></code> is the
root element of the entire configuration file, while
<code><Service
></code> represents a group of Connectors that is
associated with an Engine.
</li>
<li><strong>Connectors
</strong> - Represent the interface between external
clients sending requests to (and receiving responses from) a particular
Service.
</li>
<li><strong>Containers
</strong> - Represent components whose function is to
process incoming requests, and create the corresponding responses.
An Engine handles all requests for a Service, a Host handles all requests
for a particular virtual host, and a Context handles all requests for a
specific web application.
</li>
<li><strong>Nested Components
</strong> - Represent elements that can be
nested inside the element for a Container. Some elements can be nested
inside any Container, while others can only be nested inside a
Context.
</li>
</ul>
<p>For each element, the corresponding documentation follows this general
outline:
</p>
<ul>
<li><strong>Introduction
</strong> - Overall description of this particular
component. There will be a corresponding Java
<em>interface
</em> (in
the
<code>org.apache.catalina
</code> package) that is implemented by one
or more standard implementations.
</li>
<li><strong>Attributes
</strong> - The set of attributes that are legal for
this element. Generally, this will be subdivided into
<em>Common
</em>
attributes that are supported by all implementations of the corresponding
Java interface, and
<em>Standard Implementation
</em> attributes that are
specific to a particular Java class that implements this interface.
The names of required attributes are
<strong>bolded
</strong>.
</li>
<li><strong>Nested Components
</strong> - Enumerates which of the
<em>Nested
Components
</em> can be legally nested within this element.
</li>
<li><strong>Special Features
</strong> - Describes the configuration of a large
variety of special features (specific to each element type) that are
supported by the standard implementation of this interface.
</li>
</ul>
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