webapps/docs/config/loader.xml - tomcat80 - Git at Google

 <?xml version="1.0" encoding="UTF-8"?>
 <!--
   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
   the License.  You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
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 <!DOCTYPE document [
   <!ENTITY project SYSTEM "project.xml">
 ]>
 <document url="loader.html">

   &project;

   <properties>
     <author email="craigmcc@apache.org">Craig R. McClanahan</author>
     <title>The Loader Component</title>
   </properties>

 <body>

 <section name="Table of Contents">
 <toc/>
 </section>

 <section name="Introduction">

   <p>The <strong>Loader</strong> element represents the <em>web
   application class loader</em> that will be used to load Java
   classes and resources for your web application.  Such
   a class loader must follow the requirements of the Servlet
   Specification, and load classes from the following locations:</p>
   <ul>
   <li>From the <code>/WEB-INF/classes</code> directory inside your
       web application.</li>
   <li>From JAR files in the <code>/WEB-INF/lib</code> directory
       inside your web application.</li>
   <li>From resources made available by Catalina to all web
       applications globally.</li>
   </ul>

   <p>A Loader element MAY be nested inside a <a href="context.html">Context</a>
   component.  If it is not included, a default Loader configuration will be
   created automatically, which is sufficient for most requirements.</p>

   <p>For a more in-depth description of the class loader hierarchy
   that is implemented by Catalina, see <a href="../class-loader-howto.html">the ClassLoader HowTo</a>.</p>

     <p><em>The description below uses the variable name $CATALINA_BASE to refer the
     base directory against which most relative paths are resolved. If you have
     not configured Tomcat for multiple instances by setting a CATALINA_BASE
     directory, then $CATALINA_BASE will be set to the value of $CATALINA_HOME,
     the directory into which you have installed Tomcat.</em></p>

 </section>


 <section name="Attributes">

   <subsection name="Common Attributes">

     <p>All implementations of <strong>Loader</strong>
     support the following attributes:</p>

     <attributes>

       <attribute name="className" required="false">
         <p>Java class name of the implementation to use.  This class must
         implement the <code>org.apache.catalina.Loader</code> interface.
         If not specified, the standard value (defined below) will be used.</p>
       </attribute>

       <attribute name="delegate" required="false">
         <p>Set to <code>true</code> if you want the class loader to follow
         the standard Java2 delegation model, and attempt to load classes from
         parent class loaders <strong>before</strong> looking inside the web
         application.  Set to <code>false</code> (the default) to have the
         class loader look inside the web application first, before asking
         parent class loaders to find requested classes or resources.</p>
       </attribute>

       <attribute name="reloadable" required="false">
         <p>Set to <code>true</code> if you want Catalina to monitor classes in
         <code>/WEB-INF/classes/</code> and <code>/WEB-INF/lib</code> for
         changes, and automatically reload the web application if a change
         is detected.  This feature is very useful during application
         development, but it requires significant runtime overhead and is
         not recommended for use on deployed production applications.  You
         can use the <a href="../manager-howto.html">Manager</a> web
         application, however, to trigger reloads of deployed applications
         on demand.</p>

         <p><strong>NOTE</strong> - The value for this property will be
         inherited from the <code>reloadable</code> attribute you set on
         the surrounding <a href="context.html">Context</a> component,
         and any value you explicitly set here will be replaced.</p>
       </attribute>

     </attributes>

   </subsection>


   <subsection name="Standard Implementation">

     <p>The standard implementation of <strong>Loader</strong> is
     <strong>org.apache.catalina.loader.WebappLoader</strong>.
     It supports the following additional attributes (in addition to the
     common attributes listed above):</p>

     <attributes>

       <attribute name="loaderClass" required="false">
         <p>Java class name of the <code>java.lang.ClassLoader</code>
         implementation class to use. Custom implementations must extend
         <code>org.apache.catalina.loader.WebappClassLoaderBase</code>.
         </p>

         <p>If not specified, the default value is
         <code>org.apache.catalina.loader.WebappClassLoader</code>.  The
         default <strong>loaderClass</strong> is not parallel capable, which
         means that loading a class from this classloader is performed by one
         thread at a time. A parallel capable <strong>loaderClass</strong> is
         available and can be used by specifying
         <code>org.apache.catalina.loader.ParallelWebappClassLoader</code>.</p>
       </attribute>

     </attributes>

   </subsection>

 </section>


 <section name="Nested Components">

   <p>No components may be nested inside a <strong>Loader</strong> element.</p>

 </section>


 <section name="Special Features">

   <subsection name="Logging">

     <p>A loader is associated with the log category based on its classname.</p>

   </subsection>

 </section>


 </body>


 </document>
	<?xml version="1.0" encoding="UTF-8"?>
	<!--
	Licensed to the Apache Software Foundation (ASF) under one or more
	contributor license agreements. See the NOTICE file distributed with
	this work for additional information regarding copyright ownership.
	The ASF licenses this file to You under the Apache License, Version 2.0
	(the "License"); you may not use this file except in compliance with
	the License. You may obtain a copy of the License at

	http://www.apache.org/licenses/LICENSE-2.0

	Unless required by applicable law or agreed to in writing, software
	distributed under the License is distributed on an "AS IS" BASIS,
	WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	See the License for the specific language governing permissions and
	limitations under the License.
	-->
	<!DOCTYPE document [
	<!ENTITY project SYSTEM "project.xml">
	]>
	<document url="loader.html">

	&project;

	<properties>
	<author email="craigmcc@apache.org">Craig R. McClanahan</author>
	<title>The Loader Component</title>
	</properties>

	<body>

	<section name="Table of Contents">
	<toc/>
	</section>

	<section name="Introduction">

	<p>The <strong>Loader</strong> element represents the <em>web
	application class loader</em> that will be used to load Java
	classes and resources for your web application. Such
	a class loader must follow the requirements of the Servlet
	Specification, and load classes from the following locations:</p>
	<ul>
	<li>From the <code>/WEB-INF/classes</code> directory inside your
	web application.</li>
	<li>From JAR files in the <code>/WEB-INF/lib</code> directory
	inside your web application.</li>
	<li>From resources made available by Catalina to all web
	applications globally.</li>
	</ul>

	<p>A Loader element MAY be nested inside a <a href="context.html">Context</a>
	component. If it is not included, a default Loader configuration will be
	created automatically, which is sufficient for most requirements.</p>

	<p>For a more in-depth description of the class loader hierarchy
	that is implemented by Catalina, see <a href="../class-loader-howto.html">the ClassLoader HowTo</a>.</p>

	<p><em>The description below uses the variable name $CATALINA_BASE to refer the
	base directory against which most relative paths are resolved. If you have
	not configured Tomcat for multiple instances by setting a CATALINA_BASE
	directory, then $CATALINA_BASE will be set to the value of $CATALINA_HOME,
	the directory into which you have installed Tomcat.</em></p>

	</section>


	<section name="Attributes">

	<subsection name="Common Attributes">

	<p>All implementations of <strong>Loader</strong>
	support the following attributes:</p>

	<attributes>

	<attribute name="className" required="false">
	<p>Java class name of the implementation to use. This class must
	implement the <code>org.apache.catalina.Loader</code> interface.
	If not specified, the standard value (defined below) will be used.</p>
	</attribute>

	<attribute name="delegate" required="false">
	<p>Set to <code>true</code> if you want the class loader to follow
	the standard Java2 delegation model, and attempt to load classes from
	parent class loaders <strong>before</strong> looking inside the web
	application. Set to <code>false</code> (the default) to have the
	class loader look inside the web application first, before asking
	parent class loaders to find requested classes or resources.</p>
	</attribute>

	<attribute name="reloadable" required="false">
	<p>Set to <code>true</code> if you want Catalina to monitor classes in
	<code>/WEB-INF/classes/</code> and <code>/WEB-INF/lib</code> for
	changes, and automatically reload the web application if a change
	is detected. This feature is very useful during application
	development, but it requires significant runtime overhead and is
	not recommended for use on deployed production applications. You
	can use the <a href="../manager-howto.html">Manager</a> web
	application, however, to trigger reloads of deployed applications
	on demand.</p>

	<p><strong>NOTE</strong> - The value for this property will be
	inherited from the <code>reloadable</code> attribute you set on
	the surrounding <a href="context.html">Context</a> component,
	and any value you explicitly set here will be replaced.</p>
	</attribute>

	</attributes>

	</subsection>


	<subsection name="Standard Implementation">

	<p>The standard implementation of <strong>Loader</strong> is
	<strong>org.apache.catalina.loader.WebappLoader</strong>.
	It supports the following additional attributes (in addition to the
	common attributes listed above):</p>

	<attributes>

	<attribute name="loaderClass" required="false">
	<p>Java class name of the <code>java.lang.ClassLoader</code>
	implementation class to use. Custom implementations must extend
	<code>org.apache.catalina.loader.WebappClassLoaderBase</code>.
	</p>

	<p>If not specified, the default value is
	<code>org.apache.catalina.loader.WebappClassLoader</code>. The
	default <strong>loaderClass</strong> is not parallel capable, which
	means that loading a class from this classloader is performed by one
	thread at a time. A parallel capable <strong>loaderClass</strong> is
	available and can be used by specifying
	<code>org.apache.catalina.loader.ParallelWebappClassLoader</code>.</p>
	</attribute>

	</attributes>

	</subsection>

	</section>


	<section name="Nested Components">

	<p>No components may be nested inside a <strong>Loader</strong> element.</p>

	</section>


	<section name="Special Features">

	<subsection name="Logging">

	<p>A loader is associated with the log category based on its classname.</p>

	</subsection>

	</section>


	</body>


	</document>