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+        </style></head><body bgcolor="#ffffff" text="#000000" link="#525D76" alink="#525D76" vlink="#525D76"><table border="0" width="100%" cellspacing="0"><!--PAGE HEADER--><tr><td><!--PROJECT LOGO--><a href="http://tomcat.apache.org/"><img src="./images/tomcat.gif" align="right" alt="

+      The Apache Tomcat Servlet/JSP Container

+    " border="0"></a></td><td><h1><font face="arial,helvetica,sanserif">Apache Tomcat 7</font></h1><font face="arial,helvetica,sanserif">Version 7.0.42, Jul 2 2013</font></td><td><!--APACHE LOGO--><a href="http://www.apache.org/"><img src="./images/asf-logo.gif" align="right" alt="Apache Logo" border="0"></a></td></tr></table><table border="0" width="100%" cellspacing="4"><!--HEADER SEPARATOR--><tr><td colspan="2"><hr noshade size="1"></td></tr><tr><!--LEFT SIDE NAVIGATION--><td width="20%" valign="top" nowrap class="noPrint"><p><strong>Links</strong></p><ul><li><a href="index.html">Docs Home</a></li><li><a href="http://wiki.apache.org/tomcat/FAQ">FAQ</a></li><li><a href="#comments_section">User Comments</a></li></ul><p><strong>User Guide</strong></p><ul><li><a href="introduction.html">1) Introduction</a></li><li><a href="setup.html">2) Setup</a></li><li><a href="appdev/index.html">3) First webapp</a></li><li><a href="deployer-howto.html">4) Deployer</a></li><li><a href="manager-howto.html">5) Manager</a></li><li><a href="realm-howto.html">6) Realms and AAA</a></li><li><a href="security-manager-howto.html">7) Security Manager</a></li><li><a href="jndi-resources-howto.html">8) JNDI Resources</a></li><li><a href="jndi-datasource-examples-howto.html">9) JDBC DataSources</a></li><li><a href="class-loader-howto.html">10) Classloading</a></li><li><a href="jasper-howto.html">11) JSPs</a></li><li><a href="ssl-howto.html">12) SSL</a></li><li><a href="ssi-howto.html">13) SSI</a></li><li><a href="cgi-howto.html">14) CGI</a></li><li><a href="proxy-howto.html">15) Proxy Support</a></li><li><a href="mbeans-descriptor-howto.html">16) MBean Descriptor</a></li><li><a href="default-servlet.html">17) Default Servlet</a></li><li><a href="cluster-howto.html">18) Clustering</a></li><li><a href="balancer-howto.html">19) Load Balancer</a></li><li><a href="connectors.html">20) Connectors</a></li><li><a href="monitoring.html">21) Monitoring and Management</a></li><li><a href="logging.html">22) Logging</a></li><li><a href="apr.html">23) APR/Native</a></li><li><a href="virtual-hosting-howto.html">24) Virtual Hosting</a></li><li><a href="aio.html">25) Advanced IO</a></li><li><a href="extras.html">26) Additional Components</a></li><li><a href="maven-jars.html">27) Mavenized</a></li><li><a href="security-howto.html">28) Security Considerations</a></li><li><a href="windows-service-howto.html">29) Windows Service</a></li><li><a href="windows-auth-howto.html">30) Windows Authentication</a></li><li><a href="jdbc-pool.html">31) Tomcat's JDBC Pool</a></li><li><a href="web-socket-howto.html">32) WebSocket</a></li></ul><p><strong>Reference</strong></p><ul><li><a href="RELEASE-NOTES.txt">Release Notes</a></li><li><a href="config/index.html">Configuration</a></li><li><a href="api/index.html">Tomcat Javadocs</a></li><li><a href="servletapi/index.html">Servlet Javadocs</a></li><li><a href="jspapi/index.html">JSP 2.2 Javadocs</a></li><li><a href="elapi/index.html">EL 2.2 Javadocs</a></li><li><a href="http://tomcat.apache.org/connectors-doc/">JK 1.2 Documentation</a></li></ul><p><strong>Apache Tomcat Development</strong></p><ul><li><a href="building.html">Building</a></li><li><a href="changelog.html">Changelog</a></li><li><a href="http://wiki.apache.org/tomcat/TomcatVersions">Status</a></li><li><a href="developers.html">Developers</a></li><li><a href="architecture/index.html">Architecture</a></li><li><a href="funcspecs/index.html">Functional Specs.</a></li><li><a href="tribes/introduction.html">Tribes</a></li></ul></td><!--RIGHT SIDE MAIN BODY--><td width="80%" valign="top" align="left" id="mainBody"><h1>Jasper 2 JSP Engine How To</h1><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Table of Contents"><!--()--></a><a name="Table_of_Contents"><strong>Table of Contents</strong></a></font></td></tr><tr><td><blockquote>

+<ul><li><a href="#Introduction">Introduction</a></li><li><a href="#Configuration">Configuration</a></li><li><a href="#Known_issues">Known issues</a></li><li><a href="#Production_Configuration">Production Configuration</a></li><li><a href="#Web_Application_Compilation">Web Application Compilation</a></li><li><a href="#Optimisation">Optimisation</a></li></ul>

+</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Introduction"><strong>Introduction</strong></a></font></td></tr><tr><td><blockquote>

+

+<p>Tomcat 7.0 uses the Jasper 2 JSP Engine to implement

+the <a href="http://wiki.apache.org/tomcat/Specifications">JavaServer Pages 2.2</a>

+specification.</p>

+

+<p>Jasper 2 has been redesigned to significantly improve performance over

+the original Jasper.  In addition to general code improvements the following

+changes were made:

+<ul>

+<li><strong>JSP Custom Tag Pooling</strong> - The java objects instantiated

+for JSP Custom Tags can now be pooled and reused.  This significantly boosts

+the performance of JSP pages which use custom tags.</li>

+<li><strong>Background JSP compilation</strong> - If you make a change to

+a JSP page which had already been compiled Jasper 2 can recompile that

+page in the background.  The previously compiled JSP page will still be

+available to serve requests.  Once the new page has been compiled

+successfully it will replace the old page.  This helps improve availability

+of your JSP pages on a production server.</li>

+<li><strong>Recompile JSP when included page changes</strong> - Jasper 2

+can now detect when a page included at compile time from a JSP has changed

+and then recompile the parent JSP.</li>

+<li><strong>JDT used to compile JSP pages</strong> - The

+Eclipse JDT Java compiler is now used to perform JSP java source code

+compilation. This compiler loads source dependencies from the container

+classloader. Ant and javac can still be used.</li>

+</ul>

+</p>

+

+<p>Jasper is implemented using the servlet class

+<code>org.apache.jasper.servlet.JspServlet</code>.</p>

+

+</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Configuration"><strong>Configuration</strong></a></font></td></tr><tr><td><blockquote>

+

+<p>By default Jasper is configured for use when doing web application

+development.  See the section <a href="#Production Configuration">

+Production Configuration</a> for information on configuring Jasper

+for use on a production Tomcat server.</p>

+

+<p>The servlet which implements Jasper is configured using init parameters

+in your global <code>$CATALINA_BASE/conf/web.xml</code>.

+

+<ul>

+<li><strong>checkInterval</strong> - If development is false and checkInterval

+is greater than zero, background compiles are enabled. checkInterval is the time

+in seconds between checks to see if a JSP page (and its dependent files) needs

+to be recompiled. Default <code>0</code> seconds.</li>

+

+<li><strong>classdebuginfo</strong> - Should the class file be compiled with

+debugging information?  <code>true</code> or <code>false</code>, default

+<code>true</code>.

+</li>

+

+<li><strong>classpath</strong> - Defines the class path to be used to compile

+the generated servlets. This parameter only has an effect if the ServletContext

+attribute org.apache.jasper.Constants.SERVLET_CLASSPATH is not set. This

+attribute is always set when Jasper is used within Tomcat. By default the

+classpath is created dynamically based on the current web application.</li>

+

+<li><strong>compiler</strong> - Which compiler Ant should use to compile JSP

+pages. The valid values for this are the same as for the compiler attribute of

+Ant's

+<a href="http://ant.apache.org/manual/Tasks/javac.html#compilervalues">javac</a>

+task. If the value is not set, then the default Eclipse JDT Java compiler will

+be used instead of using Ant. There is no default value. If this attribute is

+set then <code>setenv.[sh|bat]</code> should be used to add

+<code>ant.jar</code>, <code>ant-launcher.jar</code> and <code>tools.jar</code>

+to the <code>CLASSPATH</code> environment variable.</li>

+

+<li><strong>compilerSourceVM</strong> - What JDK version are the source files

+compatible with? (Default value: <code>1.6</code>)</li>

+

+<li><strong>compilerTargetVM</strong> - What JDK version are the generated files

+compatible with? (Default value: <code>1.6</code>)</li>

+

+<li><strong>development</strong> - Is Jasper used in development mode? If true,

+the frequency at which JSPs are checked for modification may be specified via

+the modificationTestInterval parameter.<code>true</code> or <code>false</code>,

+default <code>true</code>.</li>

+

+<li><strong>displaySourceFragment</strong> - Should a source fragment be

+included in exception messages? <code>true</code> or <code>false</code>,

+default <code>true</code>.</li>

+

+<li><strong>dumpSmap</strong> - Should the SMAP info for JSR45 debugging be

+dumped to a file? <code>true</code> or <code>false</code>, default

+<code>false</code>. <code>false</code> if suppressSmap is true.</li>

+

+<li><strong>enablePooling</strong> - Determines whether tag handler pooling is

+enabled. This is a compilation option. It will not alter the behaviour of JSPs

+that have already been compiled. <code>true</code> or <code>false</code>,

+default <code>true</code>.

+</li>

+

+<li><strong>engineOptionsClass</strong> - Allows specifying the Options class

+used to configure Jasper. If not present, the default EmbeddedServletOptions

+will be used.

+</li>

+

+<li><strong>errorOnUseBeanInvalidClassAttribute</strong> - Should Jasper issue

+an error when the value of the class attribute in an useBean action is not a

+valid bean class? <code>true</code> or <code>false</code>, default

+<code>true</code>.</li>

+

+<li><strong>fork</strong> - Have Ant fork JSP page compiles so they are

+performed in a separate JVM from Tomcat? <code>true</code> or

+<code>false</code>, default <code>true</code>.</li>

+

+<li><strong>genStringAsCharArray</strong> - Should text strings be generated as char

+arrays, to improve performance in some cases? Default <code>false</code>.</li>

+

+<li><strong>ieClassId</strong> - The class-id value to be sent to Internet

+Explorer when using &lt;jsp:plugin&gt; tags.   Default

+<code>clsid:8AD9C840-044E-11D1-B3E9-00805F499D93</code>.</li>

+

+<li><strong>javaEncoding</strong> - Java file encoding to use for generating

+java source files. Default <code>UTF8</code>.</li>

+

+<li><strong>keepgenerated</strong> - Should we keep the generated Java source

+code for each page instead of deleting it? <code>true</code> or

+<code>false</code>, default <code>true</code>.</li>

+

+<li><strong>mappedfile</strong> - Should we generate static content with one

+print statement per input line, to ease debugging?

+<code>true</code> or <code>false</code>, default <code>true</code>.</li>

+

+<li><strong>maxLoadedJsps</strong> - The maximum number of JSPs that will be

+loaded for a web application. If more than this number of JSPs are loaded, the

+least recently used JSPs will be unloaded so that the number of JSPs loaded at

+any one time does not exceed this limit. A value of zero or less indicates no

+limit. Default <code>-1</code></li>

+

+<li><strong>jspIdleTimeout</strong> - The amount of time in seconds a JSP can be

+idle before it is unloaded. A value of zero or less indicates never unload.

+Default <code>-1</code></li>

+

+<li><strong>modificationTestInterval</strong> - Causes a JSP (and its dependent

+files) to not be checked for modification during the specified time interval

+(in seconds) from the last time the JSP was checked for modification. A value of

+0 will cause the JSP to be checked on every access. Used in development mode

+only. Default is <code>4</code> seconds.</li>

+

+<li><strong>recompileOnFail</strong> - If a JSP compilation fails should the

+modificationTestInterval be ignored and the next access trigger a re-compilation

+attempt? Used in development mode only and is disabled by default as compilation

+may be expensive and could lead to excessive resource usage.</li>

+

+<li><strong>scratchdir</strong> - What scratch directory should we use when

+compiling JSP pages? Default is the work directory for the current web

+application.</li>

+

+<li><strong>suppressSmap</strong> - Should the generation of SMAP info for JSR45

+debugging be suppressed? <code>true</code> or <code>false</code>, default

+<code>false</code>.</li>

+

+<li><strong>trimSpaces</strong> - Should white spaces in template text between

+actions or directives be trimmed ?, default <code>false</code>.</li>

+

+<li><strong>xpoweredBy</strong> - Determines whether X-Powered-By response

+header is added by generated servlet. <code>true</code> or <code>false</code>,

+default <code>false</code>.</li>

+</ul>

+</p>

+

+<p>The Java compiler from Eclipse JDT in included as the default compiler. It is

+an advanced Java compiler which will load all dependencies from the Tomcat class

+loader, which will help tremendously when compiling on large installations with

+tens of JARs. On fast servers, this will allow sub-second recompilation cycles

+for even large JSP  pages.</p>

+

+<p>Apache Ant, which was used in previous Tomcat releases, can be used instead

+of the new compiler by configuring the compiler attribute as explained above.

+</p>

+

+</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Known issues"><!--()--></a><a name="Known_issues"><strong>Known issues</strong></a></font></td></tr><tr><td><blockquote>

+

+<p>As described in

+<a href="https://issues.apache.org/bugzilla/show_bug.cgi?id=39089">

+bug 39089</a>, a known JVM issue,

+<a href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6294277">

+bug 6294277</a>, may cause a

+<code>java.lang.InternalError: name is too long to represent</code> exception

+when compiling very large JSPs. If this is observed then it may be worked around

+by using one of the following:

+<ul>

+<li>reduce the size of the JSP</li>

+<li>disable SMAP generation and JSR-045 support by setting

+<code>suppressSmap</code> to <code>true</code>.</li>

+</ul>

+</p>

+

+</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Production Configuration"><!--()--></a><a name="Production_Configuration"><strong>Production Configuration</strong></a></font></td></tr><tr><td><blockquote>

+

+<p>The main JSP optimization which can be done is precompilation of JSPs.

+However, this might not be possible (for example, when using the

+jsp-property-group feature) or practical, in which case the configuration of the

+Jasper servlet becomes critical.</p>

+

+<p>When using Jasper 2 in a production Tomcat server you should consider making

+the following changes from the default configuration.

+<ul>

+<li><strong>development</strong> - To disable on access checks for JSP

+pages compilation set this to <code>false</code>.</li>

+<li><strong>genStringAsCharArray</strong> - To generate slightly more efficient

+char arrays, set this to <code>true</code>.</li>

+<li><strong>modificationTestInterval</strong> - If development has to be set to

+<code>true</code> for any reason (such as dynamic generation of JSPs), setting

+this to a high value will improve performance a lot.</li>

+<li><strong>trimSpaces</strong> - To remove useless bytes from the response,

+set this to <code>true</code>.</li>

+</ul>

+</p>

+

+</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Web Application Compilation"><!--()--></a><a name="Web_Application_Compilation"><strong>Web Application Compilation</strong></a></font></td></tr><tr><td><blockquote>

+

+<p>Using Ant is the preferred way to compile web applications using JSPC. Note

+that when pre-compiling JSPs, SMAP information will only be included in the

+final classes if suppressSmap is false and compile is true.

+Use the script given below (a similar script is included in the "deployer"

+download) to precompile a webapp:

+</p>

+

+<p>

+<div align="left"><table cellspacing="4" cellpadding="0" border="0"><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#ffffff" height="1"><pre>

+&lt;project name="Webapp Precompilation" default="all" basedir="."&gt;

+

+   &lt;import file="${tomcat.home}/bin/catalina-tasks.xml"/&gt;

+

+   &lt;target name="jspc"&gt;

+

+    &lt;jasper

+             validateXml="false"

+             uriroot="${webapp.path}"

+             webXmlFragment="${webapp.path}/WEB-INF/generated_web.xml"

+             outputDir="${webapp.path}/WEB-INF/src" /&gt;

+

+  &lt;/target&gt;

+

+  &lt;target name="compile"&gt;

+

+    &lt;mkdir dir="${webapp.path}/WEB-INF/classes"/&gt;

+    &lt;mkdir dir="${webapp.path}/WEB-INF/lib"/&gt;

+

+    &lt;javac destdir="${webapp.path}/WEB-INF/classes"

+           optimize="off"

+           debug="on" failonerror="false"

+           srcdir="${webapp.path}/WEB-INF/src"

+           excludes="**/*.smap"&gt;

+      &lt;classpath&gt;

+        &lt;pathelement location="${webapp.path}/WEB-INF/classes"/&gt;

+        &lt;fileset dir="${webapp.path}/WEB-INF/lib"&gt;

+          &lt;include name="*.jar"/&gt;

+        &lt;/fileset&gt;

+        &lt;pathelement location="${tomcat.home}/lib"/&gt;

+        &lt;fileset dir="${tomcat.home}/lib"&gt;

+          &lt;include name="*.jar"/&gt;

+        &lt;/fileset&gt;

+        &lt;fileset dir="${tomcat.home}/bin"&gt;

+          &lt;include name="*.jar"/&gt;

+        &lt;/fileset&gt;

+      &lt;/classpath&gt;

+      &lt;include name="**" /&gt;

+      &lt;exclude name="tags/**" /&gt;

+    &lt;/javac&gt;

+

+  &lt;/target&gt;

+

+  &lt;target name="all" depends="jspc,compile"&gt;

+  &lt;/target&gt;

+

+  &lt;target name="cleanup"&gt;

+    &lt;delete&gt;

+        &lt;fileset dir="${webapp.path}/WEB-INF/src"/&gt;

+        &lt;fileset dir="${webapp.path}/WEB-INF/classes/org/apache/jsp"/&gt;

+    &lt;/delete&gt;

+  &lt;/target&gt;

+

+&lt;/project&gt;

+</pre></td><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr></table></div>

+</p>

+

+<p>

+The following command line can be used to run the script

+(replacing the tokens with the Tomcat base path and the path to the webapp

+which should be precompiled):<br>

+<div align="left"><table cellspacing="4" cellpadding="0" border="0"><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#ffffff" height="1"><pre>

+$ANT_HOME/bin/ant -Dtomcat.home=&lt;$TOMCAT_HOME&gt; -Dwebapp.path=&lt;$WEBAPP_PATH&gt;

+</pre></td><td bgcolor="#023264" width="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr><tr><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td><td bgcolor="#023264" width="1" height="1"><img src="./images/void.gif" alt="" width="1" height="1" vspace="0" hspace="0" border="0"></td></tr></table></div>

+</p>

+

+<p>

+Then, the declarations and mappings for the servlets which were generated

+during the precompilation must be added to the web application deployment

+descriptor. Insert the <code>${webapp.path}/WEB-INF/generated_web.xml</code>

+at the right place inside the <code>${webapp.path}/WEB-INF/web.xml</code> file.

+Restart the web application (using the manager) and test it to verify it is

+running fine with precompiled servlets. An appropriate token placed in the

+web application deployment descriptor may also be used to automatically

+insert the generated servlet declarations and mappings using Ant filtering

+capabilities. This is actually how all the webapps distributed with Tomcat

+are automatically compiled as part of the build process.

+</p>

+

+<p>

+At the jasper task you can use the option <code>addWebXmlMappings</code> for

+automatic merge the <code>${webapp.path}/WEB-INF/generated_web.xml</code>

+with the current web application deployment descriptor at

+<code>${webapp.path}/WEB-INF/web.xml</code>. When you want to use Java 6

+features inside your jsp's, add the following javac compiler task attributes:

+<code>source="1.6" target="1.6"</code>. For live

+applications you can also compile with <code>optimize="on"</code> and

+without debug info <code>debug="off"</code>.

+</p>

+

+<p>

+When you don't want to stop the jsp generation at first jsp syntax error, use

+<code>failOnError="false"</code>and with

+<code>showSuccess="true"</code> all successfull <i>jsp to java</i>

+generation are printed out. Sometimes it is very helpfull, when you cleanup the

+generate java source files at <code>${webapp.path}/WEB-INF/src</code>

+and the compile jsp servlet classes at

+<code>${webapp.path}/WEB-INF/classes/org/apache/jsp</code>.

+</p>

+

+<p><strong>Hints:</strong>

+<ul>

+<li> When you switch to another Tomcat release, then regenerate and recompile

+your jsp's with the new Tomcat version.</li>

+<li>Use java system property at server runtime to disable PageContext pooling

+<code>org.apache.jasper.runtime.JspFactoryImpl.USE_POOL=false</code>.

+and limit the buffering with

+<code>org.apache.jasper.runtime.BodyContentImpl.LIMIT_BUFFER=true</code>. Note

+that changing from the defaults may affect performance, but it will vary

+depending on the application.</li>

+</ul>

+</p>

+</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Optimisation"><strong>Optimisation</strong></a></font></td></tr><tr><td><blockquote>

+<p>

+There are a number of extension points provided within Jasper that enable the

+user to optimise the behaviour for their environment.

+</p>

+

+<p>

+The first of these extension points is the tag plug-in mechanism. This allows

+alternative implementations of tag handlers to be provided for a web application

+to use. Tag plug-ins are registered via a <code>tagPlugins.xml</code> file

+located under <code>WEB-INF</code>. A sample plug-in for the JSTL is included

+with Jasper. 

+</p>

+

+<p>

+The second extension point is the Expression Language interpreter. Alternative

+interpreters may be configured through the <code>ServletContext</code>. See the

+<code>ELInterpreterFactory</code> javadoc for details of how to configure an

+alternative EL interpreter. 

+</p>

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