It’s Only Software

I recently augmented a Spring-based project to expose some of the Spring-managed beans via JMX. Spring makes this very easy, and even if you’ve never used JMX before, this quick tutorial will let you set up your Spring beans to be viewed (and edited!) through a JMX console.

Prerequisites

Cook-Along

Add the following to your Spring XML configuration file:

<bean id="exporter"
 class="org.springframework.jmx.export.MBeanExporter"
 lazy-init="false">
  <property name="autodetect" value="true"></property>
  <property name="namingStrategy" ref="namingStrategy"></property>
  <property name="assembler" ref="assembler"></property>
</bean>
<bean id="attributeSource"
 class="org.springframework.jmx.export.annotation.AnnotationJmxAttributeSource"/>
<bean id="assembler"
 class="org.springframework.jmx.export.assembler.MetadataMBeanInfoAssembler">
  <property name="attributeSource" ref="attributeSource"/>
</bean>
<bean id="namingStrategy"
 class="org.springframework.jmx.export.naming.MetadataNamingStrategy">
  <property name="attributeSource" ref="attributeSource"/>
</bean>

This will set up a Spring-managed JMX configuration with the following attributes:

For a Java 5 deployment of Spring, these seem reasonable, and I’m surprised that they aren’t the default configuration for Spring 2.5.

Next, we’ll need to annotate our spring-managed bean with the @ManagedResource annotation. The simplest possible usage is as follows:

@ManagedResource(objectName = “bean:name=simpleBean”, description = “A sample JMX-managed bean”)

This annotation is done at the class level - Spring will auto-detect beans with this annotation and register them as MBeans with the MBean server. The next (and final) step in the tutorial is to select which attributes of our MBean that we’ll expose. We do this by annotating members (or getters and setters) with the @ManagedAttribute annotation. So our final Java code for a simple bean looks like this:

package com.mularien.jmx;
 
import org.springframework.jmx.export.annotation.ManagedAttribute;
import org.springframework.jmx.export.annotation.ManagedResource;
 
@ManagedResource(objectName = "spring:name=simpleBean", description = "A
sample JMX-managed bean")
public class SimpleBean {
 public String url;
 
 @ManagedAttribute
 public String getUrl() {
  return url;
 }
 public void setUrl(String url) {
  this.url = url;
 }
}

And now you’re done! Fire up jconsole and connect to the Tomcat server. You’ll see a JMX namespace called “spring” with the simpleBean MBean in it.

Hopefully this was a helpful introduction on how to use JMX with your Spring beans. Spring provides a whole lot of flexibility in this area, but I wanted to write this simple tutorial, as I didn’t see one that I liked already online. Enjoy (and please comment if you found this helpful/not helpful)!

Further Reading

Rob Harrop covers Spring and JMX integration well with a series of slides in his blog (warning: many spammy comments!).

The Spring documentation is a great resource (as always) with its extensive coverage of JMX and Spring.

Sun provides Essentials of the JMX API, which is a good, brief overview of JMX and MBeans.