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<!DOCTYPE document [
<!ENTITY project SYSTEM "project.xml">
]>
<document url="listeners.html">
&project;
<properties>
<title>The LifeCycle Listener Component</title>
</properties>
<body>
<section name="Table of Contents">
<toc/>
</section>
<section name="Introduction">
<p>A <strong>Listener</strong> element defines a component that performs
actions when specific events occur, usually Tomcat starting or Tomcat
stopping.</p>
<p>Listeners may be nested inside a <a href="server.html">Server</a>,
<a href="engine.html">Engine</a>, <a href="host.html">Host</a> or
<a href="context.html">Context</a>. Some Listeners are only intended to be
nested inside specific elements. These constraints are noted in the
documentation below.</p>
</section>
<section name="Attributes">
<subsection name="Common Attributes">
<p>All implementations of <strong>Listener</strong>
support the following attributes:</p>
<attributes>
<attribute name="className" required="true">
<p>Java class name of the implementation to use. This class must
implement the <code>org.apache.catalina.LifecycleListener</code>
interface.</p>
</attribute>
</attributes>
</subsection>
</section>
<section name="Nested Components">
<p>No element may be nested inside a <strong>Listener</strong>.</p>
</section>
<section name="Standard Implementation">
<p>Unlike most Catalina components, there are several standard
<strong>Listener</strong> implementations available. As a result,
the <code>className</code> attribute MUST be used to select the
implementation you wish to use.</p>
<subsection name="APR Lifecycle Listener - org.apache.catalina.core.AprLifecycleListener">
<p>The <strong>APR Lifecycle Listener</strong> checks for the presence of
the APR/native library and loads the library if it is present. For more
information see the <a href="../apr.html">APR/native guide</a>.</p>
<p>This listener must only be nested within <a href="server.html">Server</a>
elements.</p>
<p>The following additional attributes are supported by the <strong>APR
Lifecycle Listener</strong>:</p>
<attributes>
<attribute name="SSLEngine" required="false">
<p>Name of the SSLEngine to use. <code>off</code>: do not use SSL,
<code>on</code>: use SSL but no specific ENGINE.</p>
<p>The default value is <b>on</b>. This initializes the
native SSL engine, which must be enabled in the APR/native connector by
the use of the <code>SSLEnabled</code> attribute.</p>
<p>See the <a href="http://www.openssl.org/">Official OpenSSL website</a>
for more details on supported SSL hardware engines and manufacturers.
</p>
</attribute>
<attribute name="SSLRandomSeed" required="false">
<p>Entropy source used to seed the SSLEngine's PRNG. The default value
is <code>builtin</code>. On development systems, you may want to set
this to <code>/dev/urandom</code> to allow quicker start times.</p>
</attribute>
<attribute name="FIPSMode" required="false">
<p>Set to <code>on</code> to instruct OpenSSL to go into FIPS mode.
FIPS mode <em>requires you to have a FIPS-capable OpenSSL library which
you must build yourself</em>.
FIPS mode also requires Tomcat native library version 1.1.23 or later,
which <em>must be built against the FIPS-compatible OpenSSL</em> library.
If this attribute is "on", <b>SSLEngine</b> must be enabled as well.
The default value is <code>off</code>.</p>
</attribute>
</attributes>
</subsection>
<subsection name="Jasper Listener - org.apache.catalina.core.JasperListener">
<p>The <strong>Jasper Listener</strong> initializes the Jasper 2 JSP engine
before any web applications that may use it are loaded. For more
information on the Jasper 2 JSP engine see the
<a href="../jasper-howto.html">Jasper How To</a>.</p>
<p>This listener must only be nested within <a href="server.html">Server</a>
elements.</p>
<p>No additional attributes are supported by the <strong>Jasper Listener
</strong>.</p>
</subsection>
<subsection name="Server Lifecycle Listener - org.apache.catalina.mbeans.ServerLifecycleListener">
<p>The <strong>Server Lifecycle Listener</strong> initializes the
MBeanServer for the MBeans that may be used to manage Tomcat via JMX.
Without this listener, none of the Tomcat MBeans will be available.</p>
<p>This listener must only be nested within <a href="server.html">Server</a>
elements.</p>
<p>No additional attributes are supported by the <strong>Server Lifecycle
Listener</strong>.</p>
</subsection>
<subsection name="Global Resources Lifecycle Listener - org.apache.catalina.mbeans.GlobalResourcesLifecycleListener">
<p>The <strong>Global Resources Lifecycle Listener</strong> initializes the
Global JNDI resources defined in server.xml as part of the <a
href="globalresources.html">Global Resources</a> element. Without this
listener, none of the Global Resources will be available.</p>
<p>This listener must only be nested within <a href="server.html">Server</a>
elements.</p>
<p>No additional attributes are supported by the <strong>Global Resources
Lifecycle Listener</strong>.</p>
</subsection>
<subsection name="JMX Remote Lifecycle Listener - org.apache.catalina.mbeans.JmxRemoteLifecycleListener">
<p>This listener requires <code>catalina-jmx-remote.jar</code> to be placed
in <code>$CATALINA_HOME/lib</code>. This jar may be found in the extras
directory of the binary download area.</p>
<p>The <strong>JMX Remote Lifecycle Listener</strong> fixes the ports used by
the JMX/RMI Server making things much simpler if you need to connect
jconsole or a similar tool to a remote Tomcat instance that is running
behind a firewall. Only these ports are configured via the listener. The
remainder of the configuration is via the standard system properties for
configuring JMX. For further information on configuring JMX see
<a href="http://docs.oracle.com/javase/6/docs/technotes/guides/management/agent.html">
Monitoring and Management Using JMX</a> included with the Java SDK
documentation.</p>
<p>If this listener was configured in server.xml as:
<source>
<Listener className="org.apache.catalina.mbeans.JmxRemoteLifecycleListener"
rmiRegistryPortPlatform="10001" rmiServerPortPlatform="10002" />
</source>
with the following system properties set (e.g. in setenv.sh):
<source>
-Dcom.sun.management.jmxremote.password.file=$CATALINA_BASE/conf/jmxremote.password
-Dcom.sun.management.jmxremote.access.file=$CATALINA_BASE/conf/jmxremote.access
-Dcom.sun.management.jmxremote.ssl=false
</source>
$CATALINA_BASE/conf/jmxremote.password containing:
<source>
admin letmein
</source>
$CATALINA_BASE/conf/jmxremote.access containing:
<source>
admin readwrite
</source>
then opening ports 10001 (RMI Registry) and 10002 (JMX/RMI Server) in your
firewall would enable jconsole to connect to a Tomcat instance running
behind a firewall using a connection string of the form:
<source>
service:jmx:rmi://<hostname>:10002/jndi/rmi://<hostname>:10001/jmxrmi
</source>
with a user name of <code>admin</code> and a password of
<code>letmein</code>.
</p>
<p><strong>Note that the example above does not use SSL. JMX access should
be considered equivalent to administrative access and secured accordingly.
</strong></p>
<p>This listener must only be nested within a <a href="server.html">Server</a>
element.</p>
<p>The following additional attributes are supported by the <strong>JMX Remote
Lifecycle Listener</strong>:</p>
<attributes>
<attribute name="rmiRegistryPortPlatform" required="true">
<p>The port to be used by the JMX/RMI registry for the Platform MBeans.
The replaces the use of the
<code>com.sun.management.jmxremote.port</code> system property that
should not be set when using this valve.</p>
</attribute>
<attribute name="rmiServerPortPlatform" required="true">
<p>The port to be used by the Platform JMX/RMI server.</p>
</attribute>
<attribute name="useLocalPorts" required="false">
<p>Should any clients using these ports be forced to use local ports to
connect to the the JMX/RMI server. This is useful when tunnelling
connections over SSH or similar. Defaults to <code>false</code>.</p>
</attribute>
</attributes>
</subsection>
<subsection name="JRE Memory Leak Prevention Listener - org.apache.catalina.core.JreMemoryLeakPreventionListener">
<p>The <strong>JRE Memory Leak Prevention Listener</strong> provides
work-arounds for known places where the Java Runtime environment uses
the context class loader to load a singleton as this will cause a memory
leak if a web application class loader happens to be the context class
loader at the time. The work-around is to initialise these singletons when
this listener starts as Tomcat's common class loader is the context class
loader at that time. It also provides work-arounds for known issues that
can result in locked JAR files.</p>
<p>This listener must only be nested within <a href="server.html">Server</a>
elements.</p>
<p>The following additional attributes are supported by the <strong>JRE
Memory Leak Prevention Listener</strong>:</p>
<attributes>
<attribute name="appContextProtection" required="false">
<p>Enables protection so that calls to
<code>sun.awt.AppContext.getAppContext()</code> triggered by a web
application do not result in a memory leak. Note that a call to this
method will be triggered as part of the web application stop process so
it is strongly recommended that this protection is enabled. The default
is <code>true</code>.</p>
</attribute>
<attribute name="AWTThreadProtection" required="false">
<p>Enables protection so that calls to
<code>java.awt.Toolkit.getDefaultToolkit()</code> triggered by a web
application do not result in a memory leak.
Defaults to <code>false</code> because an AWT thread is launched.</p>
</attribute>
<attribute name="classesToInitialize" required="false">
<p>List of comma-separated fully qualified class names to load and initialize
during the startup of this Listener. This allows to pre-load classes that are
known to provoke classloader leaks if they are loaded during a request
processing. Non-JRE classes may be referenced, like
<code>oracle.jdbc.driver.OracleTimeoutThreadPerVM</code>.
The default value is empty, but specific JRE classes are loaded by other leak
protection features managed by other attributes of this Listener.</p>
</attribute>
<attribute name="driverManagerProtection" required="false">
<p>The first use of <code>java.sql.DriverManager</code> will trigger the
loading of JDBC Driver in the the current class loader. The web
application level memory leak protection can take care of this in most
cases but triggering the loading here has fewer side-effects. The
default is <code>true</code>.</p>
</attribute>
<attribute name="gcDaemonProtection" required="false">
<p>Enables protection so that calls to
<code>sun.misc.GC.requestLatency(long)</code> triggered by a web
application do not result in a memory leak. Use of RMI is likely to
trigger a call to this method. A side effect of enabling this protection
is the creation of a thread named "GC Daemon". The protection uses
reflection to access internal Sun classes and may generate errors on
startup on non-Sun JVMs. The default is <code>true</code>.</p>
</attribute>
<attribute name="ldapPoolProtection" required="false">
<p>Enables protection so that the PoolCleaner thread started by
<code>com.sun.jndi.ldap.LdapPoolManager</code> does not result in a
memory leak. The thread is started the first time the
<code>LdapPoolManager</code> class is used if the system property
<code>com.sun.jndi.ldap.connect.pool.timeout</code> is set to a value
greater than 0. Without this protection, if a web application uses this
class the PoolCleaner thread will be configured with the thread's
context class loader set to the web application class loader which in
turn will trigger a memory leak on reload. Defaults to
<code>true</code>.</p>
</attribute>
<attribute name="securityLoginConfigurationProtection" required="false">
<p>Enables protection so that usage of the
<code>javax.security.auth.login.Configuration</code> class by a web
application does not provoke a memory leak. The first access of this
class will trigger the initializer that will retain a static reference
to the context class loader. The protection loads the class with the
system class loader to ensure that the static initializer is not
triggered by a web application. Defaults to <code>true</code>.</p>
</attribute>
<attribute name="securityPolicyProtection" required="false">
<p>Enables protection so that usage of the deprecated
<code>javax.security.auth.Policy</code> class by a web application does not
result in a memory leak. The first access of this class will trigger the
static initializer that will retain a static reference to the context
class loader. The protection calls the <code>getPolicy()</code> method
of this class to ensure that the static initializer is not triggered by
a web application. Defaults to <code>true</code>.</p>
</attribute>
<attribute name="tokenPollerProtection" required="false">
<p>Enables protection so that any token poller thread initialized by
<code>sun.security.pkcs11.SunPKCS11.initToken()</code> does not
result in a memory leak. The thread is started depending on various
conditions as part of the initialization of the Java Cryptography
Architecture. Without the protection this can happen during Webapp
deployment when the MessageDigest for generating session IDs is
initialized. As a result the thread has the Webapp class loader as its
thread context class loader. Enabling the protection initializes JCA
early during Tomcat startup. Defaults to <code>true</code>.</p>
</attribute>
<attribute name="urlCacheProtection" required="false">
<p>Enables protection so that reading resources from JAR files using
<code>java.net.URLConnection</code>s does not result in the JAR file
being locked. Note that enabling this protection disables caching by
default for all resources obtained via
<code>java.net.URLConnection</code>s. Caching may be re-enabled on a
case by case basis as required. Defaults to <code>true</code>.</p>
</attribute>
<attribute name="xmlParsingProtection" required="false">
<p>Enables protection so that parsing XML files within a web application
does not result in a memory leak. Note that memory profilers may not
display the GC root associated with this leak making it particularly
hard to diagnose. Defaults to <code>true</code>.</p>
</attribute>
</attributes>
</subsection>
</section>
</body>
</document>