Last night, I setup Tomcat monitoring for a Railo application deployed on Tomcat 6. Of course, Tomcat is just a servlet container so these instructions will work for any web-app deployed on Tomcat including Adobe ColdFusion, Spring, Groovy or your custom Web application.

This brief tutorial guides you on setting up JavaMelody which monitors a wealth of data–I've summarized a list at the end of this post.

Setup JavaMelody on your Tomcat Server: Step One

Download the JavaMelody zip file (v. 1.25.0 as of this writing) and copy the "jira-javamelody.jar" and "jrobin-1.5.9.1.jar" files to your web application's /WEB-INF/lib directory.

Setup JavaMelody on your Tomcat Server: Step Two

Edit your /WEB-INF/web.xml file and add the highlighted lines (10 through 21) directly below your title and description.

<?xml version="1.0" encoding="ISO-8859-1"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
   version="2.5">
   
	<display-name>Your Application</display-name>
	<description>Your Application</description>
	
	<!-- Monitor -->
	<filter>
		<filter-name>monitoring</filter-name>
		<filter-class>net.bull.javamelody.MonitoringFilter</filter-class>
	</filter>
	<filter-mapping>
		<filter-name>monitoring</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>
	<listener>
		<listener-class>net.bull.javamelody.SessionListener</listener-class>
	</listener>
  
	<!-- URL Rewrite -->
	<filter>
		<filter-name>UrlRewriteFilter</filter-name>
		<filter-class>org.tuckey.web.filters.urlrewrite.UrlRewriteFilter</filter-class>
	</filter>
	<filter-mapping>
		<filter-name>UrlRewriteFilter</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>
</web-app>

Setup JavaMelody on your Tomcat Server: Step Three (Optional)

This step is optional and only needed if you are using Tuckey for URL Rewriting. Edit your /WEB-INF/urlrewrite.xml file to exclude the /monitoring directory for rewriting.

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE urlrewrite PUBLIC "-//tuckey.org//DTD UrlRewrite 3.2//EN" "http://tuckey.org/res/dtds/urlrewrite3.2.dtd">
 <!--
 
    Configuration file for UrlRewriteFilter
    http://tuckey.org/urlrewrite/
 
-->
<urlrewrite>
	<rule>
		<note>
			Enable TomCat to have SES links.
		</note>
		<condition type="request-uri" operator="notequal">\.(bmp|gif|jpe?g|png|css|js|txt|pdf|doc|xls|xml|cfc|ico|php|asp)$</condition>
		<!-- Notice the last entry of "monitoring" -->
		<from>^/(?!cdn|src|railo-context|test|mxunit|remote|monitoring)(.*)$</from>
		<to>/index.cfm/$1</to>
	</rule>
</urlrewrite>

Setup JavaMelody on your Tomcat Server: Last Step

Restart your tomcat instance and visit http://yoursite/monitoring–which, for my development machine is http://localhost:8888/monitoring

Some features of JavaMelody

• Used Memory
• CPU Usage as a percent
• HTTP Sessions
• Active Threads
• Active JDBC Connections
• Used JDBC Connections
• HTTP hits per minuite
• HTTP mean response times
• % of requests that resulted in an HTTP error
• SQL hits per minuite
• SQL mean response time
• % of SQL requests resulting in an error
• % Garbade Collector Time
• Threads Count
• Loaded classes count (in kilobytes)
• Used non-heap memory
• Used physical memory for the machine
• Used swap space on the machine
• Mean age of http sessions in minutes
• Tomcat busy ghreads
• Bytes received per minute
• Bytes sent per minute
• JSP/CFM hits per minute
• JSP mean response time
• % of JSP errors