TAFJ Sessions and Technical Monitoring

To disable monitoring, you need to set javamelody.disabled=true.

<!-- turn off javamelody -->
<context-param>
<param-name>javamelody.disabled</param-name>
<param-value>false</param-value>
</context-param>

You can use the javamelody.displayed-counters parameter to override the counters displayed by default. As TAFJJEE does not make use of http session, we remove some of them.

<!-- counters - we don't want to display the default one "http,sql,error,log"
as we don't need http monitoring -->
<context-param>
<param-name>javamelody.displayed-counters</param-name>
<param-value>sql,log,ejb</param-value>
</context-param>

By default, a jndi lookup is issued to retrieve all data sources declared at application level. The optional parameter javamelody.datasources allows declaring the data sources to monitor if there is a need to exclude the locking data source or websphere internal EJB timer derby data source.

<!-- datasources to be monitored -->
	<!-- they could be retrieved dynamically through jndi lookup but we might want to exclude some -->
	<!-- i.e. WAS internal derby DS for EJBTimer or locking DS -->
	<context-param>
		<param-name>javamelody.datasources</param-name>
		<param-value>java:comp/env/jdbc/t24DataSource,java </param-value>
	</context-param>	

The multiple data sources (if any) need to be coma separated. The first data source is displayed in the Database Information screen. They also need to be defined at TAFJEE.war level to have the jndi lookup resolved (optional if the property is not used).

By default, JavaMelody stores graphs in .rrd files for and statistics in .gz files on disk in the temporary directory of the application server or in the temporary directory of the host, defined by the java.io.tmpdir system property. This is the directory to clear to clean up all statistics and graphs.

The javamelody.storage-directory property is used to override the default temporary directory.

<!-- statistic storage directory -->
<context-param>
<param-name>javamelody.storage-directory</param-name>
<param-value>C:\javamelody-storage-dir</param-value>
</context-param>

If the name of the directory starts with /, with drive specifier followed by \ or if its prefix is \\, it is considered as an absolute path. If not, it is considered as relative to the temporary directory. If this parameter is changed it is recommended to rename the physical directory as well.

The javamelody.no-database property disables all SQL and JDBC monitoring when set to true. In that case, SQL counters are not displayed.

<!-- turn off sql monitoring when set to true -->
<context-param>
<param-name>javamelody.no-database</param-name>
<param-value>false</param-value>
</context-param>

The log-threshold-level property is specific to the patched TAFJJEE JavaMelody version.

By default, JavaMelody reports warning and error messages from different application logging systems (java util logging, log4j, logback).

This parameter allows refining this setup. By default we want to report only ERROR messages. It could also be used to turn off this functionality.

It is not recommended to use the lowest logger level value because of its verbosity and the intended purpose of this functionality is to report only the last 100 log messages received.

The valid values of this parameter are:

• ERROR
• WARNING
• INFO
• DEBUG
• OFF

When set to OFF, the log counter is not displayed.

<context-param>
<param-name>javamelody.log-threshold-level</param-name>
<param-value>ERROR</param-value>
</context-param>

This parameter d should be used only during development phase and not production.

By adding javamelody.sampling-seconds property, the hotspot detection will be enabled and stack-trace sampling will be executed every x seconds according the property value. The recommended value for the lowest overhead is 10 seconds, but could be lower (1, 0.1) in case of expected faster test results.

<!-- hotspot detection -->
<context-param>
<param-name>javamelody.sampling-seconds</param-name>
<param-value>10</param-value>
</context-param>

The javamelody.sampling-excluded-packages property refines the default list of package excluded during hotspot detection.

<context-param>
<param-name>javamelody.sampling-excluded-packages</param-name>
<param-value>java,sun,com.sun,javax,org.apache,org.hibernate,oracle,org.postgresql,org.eclipse,org.jboss,com.arjuna,org.jnp</param-value>
</context-param>

When deploying JavaMelody in websphere (till version 8.5), the monitoring filter is not automatically initialised at application startup as it is according to the servlet specification.

You need to add the com.ibm.ws.webcontainer.invokeFilterInitAtStartup = true custom property to the webcontainer of the server. Otherwise the monitoring filter will not start until the TAFJEE servlet gets invoked.

By default, JavaMelody core does not provide rewrapping to monitor websphere data source. It produces the following error.

FFDC Exception:javax.naming.NamingException SourceId:com.ibm.ws.naming.util.Helpers.processJavaObjectForBinding ProbeId:682 Reporter:java.lang.Class@a18ab83c

javax.naming.NamingException: com.sun.proxy.$Proxy43.getReference() returned null in violation of the JNDI API
at com.ibm.ws.naming.util.Helpers.processJavaObjectForBinding(Helpers.java:670)
at com.ibm.ws.naming.jndicos.CNContextImpl.doRebind(CNContextImpl.java:2076)
at com.ibm.ws.naming.jndicos.CNContextImpl.rebind(CNContextImpl.java:697)
at com.ibm.ws.naming.util.WsnInitCtx.rebind(WsnInitCtx.java:233)
at com.ibm.ws.naming.util.WsnInitCtx.rebind(WsnInitCtx.java:245)
at org.apache.aries.jndi.DelegateContext.rebind(DelegateContext.java:177)
at javax.naming.InitialContext.rebind(InitialContext.java:452)
at net.bull.javamelody.JdbcWrapperHelper.rebindDataSource(JdbcWrapperHelper.java:119)
at net.bull.javamelody.JdbcWrapper.rebindDataSources(JdbcWrapper.java:452)