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06/09/2009

Tomcat Management: Use the JMXProxy to Change Configuration

After a short break to cover some interesting news over the past couple weeks and to switch templates in Blogger, this series returns with setting configuration values using the JMXProxy. Also, breaking with tradition in this series using Groovy and HTTPBuilder for the 'getting' script examples, the 'setting' portion of this series will use Ruby with the HTTParty gem. There is a fairly good reason why I'm not using Groovy and HTTPBuilder for this next batch of posts--it doesn't work! However, I do not believe that this is the fault of Groovy, HTTPBuilder, or Tomcat. Blame can solidly be placed on my limited programming skills.

One important thing to keep in mind when setting configuration values with the JMXProxy: It ain't permanent! Like the JMX-Console in JBoss, the JMXProxy allows you to Get or Set configuration details at run-time and if one were to restart tomcat, any changes that were made would be reverted back to values stored in your web.xml, server.xml, or other configuration files. So what good is it? Well, you can set logging levels at run-time to better debug a production issue or you could, in theory, create a run-time configuration that is built dynamically after startup without ever having to modify a configuration file outside of tomcat-users.xml.

The example below provides (hopefully!) a useful example meant to illustrate some basic changes that can be made to tomcat. It prints the current configuration of the http connector, then it enables HTTP compression and raises MaxThreads to 400, then reverts everything back pausing after each step so that you can witness the changes. For simplicity, I've set a basic tomcat manager UID and Password to "tomcat".

#!/usr/bin/env ruby

require 'rubygems'
require 'httparty'

class JMXProxy
 include HTTParty
 format :html
 basic_auth 'tomcat', 'tomcat'
end

puts JMXProxy.get('http://localhost:8080/manager/jmxproxy/?qry=Catalina:type=Connector,port=8080')
puts
puts 'Pausing 10 seconds - Changing Settings'
sleep(10)

puts JMXProxy.get('http://localhost:8080/manager/jmxproxy/?set=Catalina:type=Connector,port=8080&att=compression&val=on')
puts JMXProxy.get('http://localhost:8080/manager/jmxproxy/?set=Catalina:type=Connector,port=8080&att=maxThreads&val=400')
puts JMXProxy.get('http://localhost:8080/manager/jmxproxy/?qry=Catalina:type=Connector,port=8080')
puts
puts "Check it out! Resetting changes in 10 seconds..."
sleep(10)

puts JMXProxy.get('http://localhost:8080/manager/jmxproxy/?set=Catalina:type=Connector,port=8080&att=compression&val=off')
puts JMXProxy.get('http://localhost:8080/manager/jmxproxy/?set=Catalina:type=Connector,port=8080&att=maxThreads&val=40')
puts JMXProxy.get('http://localhost:8080/manager/jmxproxy/?qry=Catalina:type=Connector,port=8080')

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