craigmcc 01/10/03 15:00:41
Modified: webapps/tomcat-docs class-loader-howto.xml
Log:
Update the Class Loader doc for the HEAD branch to reflect the revised
state of the world.
Revision Changes Path
1.2 +36 -93 jakarta-tomcat-4.0/webapps/tomcat-docs/class-loader-howto.xml
Index: class-loader-howto.xml
===================================================================
RCS file: /home/cvs/jakarta-tomcat-4.0/webapps/tomcat-docs/class-loader-howto.xml,v
retrieving revision 1.1
retrieving revision 1.2
diff -u -r1.1 -r1.2
--- class-loader-howto.xml 2001/09/04 04:39:04 1.1
+++ class-loader-howto.xml 2001/10/03 22:00:41 1.2
@@ -8,7 +8,7 @@
<properties>
<author email="[EMAIL PROTECTED]">Craig R. McClanahan</author>
- <title>Class Loader INFO</title>
+ <title>Class Loader HOW-TO</title>
</properties>
<body>
@@ -27,15 +27,11 @@
application archive.</li>
<li>For classes and resources that must be shared across all web applications,
place unpacked classes and resources under
- <code>$CATALINA_HOME/classes</code>, or place JAR files containing those
- classes and resources under <code>$CATALINA_HOME/lib</code>.</li>
+ <code>$CATALINA_HOME/shared/classes</code>, or place JAR files
+ containing those classes and resources under
+ <code>$CATALINA_HOME/shared/lib</code>.</li>
</ul>
-<p><strong>WARNING</strong> - Unlike Tomcat 3.x, Tomcat 4 does
-<strong>NOT</strong> make an XML parser visible to web applications by default.
-If you need to do this, see <a href="#Tomcat 4 and XML Parsers">Tomcat 4 and
-XML Parsers</a>, below.</p>
-
</section>
@@ -70,8 +66,6 @@
Catalina Shared
/ \
Webapp1 Webapp2 ...
- / /
- Jasper1 Jasper2 ...
</source>
<p>The characteristics of each of these class loaders, including the source
@@ -118,13 +112,16 @@
<li><em>jndi.jar</em> - The Java Naming and Directory Interface API
classes (loaded <strong>ONLY</strong> on a JDK 1.2 system, because they
are included automatically on JDK 1.3 and later).</li>
- <li><em>naming.jar</em> - The JNDI implementation used by Tomcat 4 to
- represent the default JNDI naming context provided to web
- applications.</li>
- <li><em>resources.jar</em> - Resource factory classes for the JNDI naming
- context that is used internally to represent the static resources of
- a web application.</li>
+ <li><em>naming-common.jar</em> - The JNDI implementation used by Tomcat 4
+ to represent in-memory naming contexts.</li>
+ <li><em>naming-resources.jar</em> - The specialized JNDI naming context
+ implementation used to represent the static resources of a web
+ application.</li>
<li><em>servlet.jar</em> - The Servlet and JSP API classes.</li>
+ <li><em>xerces.jar</em> - The XML parser that is visible by default to
+ Tomcat internal classes and to web applications. This can be
+ overridden, for a particular web application, by including your
+ desired parser in <code>/WEB-INF/lib</code>.</li>
</ul></li>
<li><strong>Catalina</strong> - This class loader is initialized to include
all classes and resources required to implement Tomcat 4 itself. These
@@ -137,34 +134,41 @@
<ul>
<li><em>catalina.jar</em> - Implementation of the Catalina servlet
container portion of Tomcat 4.</li>
- <li><em>crimson.jar</em> - Parser portion of the JAXP/1.1 reference
- implementation, used to parse web application deployment descriptor
- (<code>web.xml</code>) files, as well as the server configuration file
- (<code>$CATALINA_HOME/conf/server.xml</code>).</li>
<li><em>jakarta-regexp-X.Y.jar</em> - The binary distribution of the
<a href="http://jakarta.apache.org/regexp/";>Jakarta Regexp</a>
regular expression processing library, used in the implementation of
request filters.</li>
- <li><em>jaxp.jar</em> - JAXP API portion of the JAXP/1.1 reference
- implementation, used to parse web application deployment descriptor
- (<code>web.xml</code>) files, as well as the server configuration file
- (<code>$CATALINA_HOME/conf/server.xml</code>).</li>
+ <li><em>servlets-xxxxx.jar</em> - The classes associated with each
+ internal servlet that provides part of Tomcat's functionality.
+ These are separated so that they can be completely removed if the
+ corresponding service is not required, or they can be subject to
+ specialized security manager permissions.</li>
+ <li><em>tomcat-ajp.jar</em> - Classes for the Java portion of the
+ <code>mod_jk</code> web server connector, which allows Tomcat to
+ run behind web servers such as Apache and iPlanet iAS and iWS.</li>
+ <li><em>tomcat-util.jar</em> - Utility classes required by
+ <em>tomcat-ajp.jar</em>.</li>
<li><em>warp.jar</em> - Classes for the Java portion of the
<code>mod_webapp</code> web server connector, which allows Tomcat to
run behind web servers such as Apache and iPlanet iAS and iWS.</li>
</ul></li>
<li><strong>Shared</strong> - This class loader is the place to put classes
and resources that you wish to share across <strong>ALL</strong>
- web applications (unless Tomcat internal classes also need access, which
- is an unusual case). All unpacked classes and resources in
- <code>$CATALINA_HOME/classes</code>, as well as classes and resources
- in JAR files under <code>$CATALINA_HOME/lib</code>, are made visible
- through this class loader. By default, that includes the following:
+ web applications (unless Tomcat internal classes also need access,
+ in which case you should put them in the <strong>Common</strong>
+ class loader instead). All unpacked classes and resources in
+ <code>$CATALINA_HOME/shared/classes</code>, as well as classes and
+ resources in JAR files under <code>$CATALINA_HOME/lib</code>, are
+ made visible through this class loader. By default, that includes
+ the following:
<ul>
+ <li><em>jasper-compiler.jar</em> - The page compiler classes required
+ to convert JSP source pages into executable servlets and compile
+ them.</li>
<li><em>jasper-runtime.jar</em> - The runtime support classes required
to execute JSP pages that have already been translated into Java
servlets and then compiled.</li>
- <li><em>namingfactory.jar</em> - JNDI object factories for resources
+ <li><em>naming-factory.jar</em> - JNDI object factories for resources
supported by the default JNDI naming context provided to web
applications.</li>
</ul></li>
@@ -175,14 +179,6 @@
under the <code>/WEB-INF/lib</code> directory of your web application
archive, are made visible to the containing web application, but to
no others.</li>
-<li><strong>JasperX</strong> - If your web application uses JSP pages, Tomcat
- also creates an additional class loader for the web application,
- containing the JSP compiler and classes it depends on. It is initialized
- to include all JAR files found in <code>$CATALINA_HOME/jasper</code>.
- Because this is a child class loader of the web application class loader,
- the Jasper compiler (and the pages that it compiles) can see all of the
- application bean classes visible in the <code>Webapp</code> class loader.
- </li>
</ul>
<p>As mentioned above, the web application class loader diverges from the
@@ -202,62 +198,9 @@
<li>System class loader classses (described above)</li>
<li><em>$CATALINA_HOME/common/classes</em></li>
<li><em>$CATALINA_HOME/common/*.jar</em></li>
-<li><em>$CATALINA_HOME/classes</em></li>
-<li><em>$CATALINA_HOME/lib/*.jar</em></li>
+<li><em>$CATALINA_HOME/shared/classes</em></li>
+<li><em>$CATALINA_HOME/shared/lib/*.jar</em></li>
</ul>
-
-</section>
-
-
-<section name="Tomcat 4 and XML Parsers">
-
-<p>Tomcat 4 itself utilizes XML parsing for three processing activities:</p>
-<ul>
-<li>Parsing the <code>server.xml</code> configuration file</li>
-<li>Parsing <code>web.xml</code> deployment descriptors</li>
-<li>Parsing JSP pages in XML syntax</li>
-</ul>
-
-<p>By default, the Java API for XML Processing (Version 1.1) reference
-implementation is utilized for all of these purposes. However, this parser
-is <strong>not</strong> visible to web applications -- instead, the XML
-parser stored in <code>$CATALINA_HOME/server/lib</code> is used for parsing
-<code>web.xml</code> and <code>server.xml</code> files, while the parser
-stored in <code>$CATALINA_HOME/jasper</code> is used for parsing JSP pages
-in XML syntax.</p>
-
-<p>To make an XML parser available to your web applications, you have several
-options:</p>
-<ul>
-<li>To utilize an XML parser in a single web application, simply include the
- parser's JAR files in the <code>/WEB-INF/web.xml</code> directory of that
- web application. This will work, no matter what parser might be used by
- Tomcat 4 internally, or by other web applications running in the same
- instance of Tomcat 4.</li>
-<li>If you wish to make the JAXP/1.1 reference implementation parser available
- to all web applications, simply move the "jaxp.jar" and "crimson.jar" files
- from the <code>$CATALINA_HOME/jasper</code> directory into the
- <code>$CATALINA_HOME/lib</code> directory. Jasper will continue to use
- this parser for processing JSP pages in XML syntax.</li>
-<li>If you wish to make another XML parser that is JAXP/1.1 compatible
- (such as Xerces 1.3.1 or later), install that parser's JAR files into the
- <code>$CATALINA_HOME/lib</code> directory, and remove "jaxp.jar" and
- "crimson.jar" from the <code>$CATALINA_HOME/jasper</code> directory.
- Jasper will then utilize the new XML parser as well.</li>
-</ul>
-
-<p><strong>WARNING</strong> - Do not attempt to use a JAXP/1.0 (rather than
-JAXP/1.1) compliant parser with Tomcat 4. Tomcat relies on the extra features
-that were added in JAXP/1.1 to perform its parsing activities.</p>
-
-<p><strong>WARNING</strong> - The final release of the JAXP/1.1 reference
-implementation includes JAR files with the <code>sealed</code> attribute.
-This causes class loading problems (most commonly visible through "package
-sealing violation" exceptions) on JDK 1.3 and later platforms. To avoid
-these problems, <em>modified</em> versions of "jaxp.jar" and "crimson.jar"
-are shipped with Tomcat 4. You must <strong>NOT</strong> replace these files
-with standard JAXP/1.1 JAR files, until a subsequent JAXP release occurs that
-has the "sealed" attribute removed.</p>
</section>
