Jmx4perl Mule Agent

In its standalone mode, Mule provides a simple to use interface for custom agents to plug in. This blog post is about the new jmx4perl mule agent which can be used with jmx4perl and the Nagios check check_jmx4perl.

Mule is one of the leading ESBs which can be used either as a web application or in standalone mode. For monitoring purposes it exposes its management interfaces via JMX, so jmx4perl can be used for a lightweight JMX remote access here as well. When used as a JEE web application the usual jmx4perl agent can be deployed in parallel as a servlet, so no special setup is required here.

When Mule is operating in standalone mode things are a bit different. Mule is not a servlet container so deploying a vanilla j4p.war is not possible. Mule itself is able to export JMX interfaces via regular JSR-160 remoting by the use of so called agents. Since version 0.50 jmx4perl has a proxy mode for accessing Mule JMX MBeans remotely. However a more direct connection would be preferable to avoid the somewhat evolved proxy setup.

Luckily Mule 2.1 provides a nice interface for custom agent where jmx4perl can plug into. The current jmx4perl 0.50 contains such an agent which can be integrated into a Mule installation. Actually, the agent needs to be build separately by calling mvn install in the agent/ subdirectory. You will find the final agent in agent/modules/j4p-mule/target. You can also download the agent directly from our maven repository.

The following steps are required for installing the agent:

• Save the agent jar within your Mule installation in lib/opt/
• Adapt your Mule configuration to contain the following section:

<management:custom-agent name="j4p-agent" class="org.jmx4perl.mule.J4pAgent">
  <spring:property name="port" value="8899"/>
</management:custom-agent>
<management:jmx-server/>

• Startup Mule

The startup message should contain something like

*********************************************************
* Mule ESB and Integration Platform                     *
* Version: 2.2.1 Build: 14422                           *
* MuleSource, Inc.                                      *
* For more information go to http://mule.mulesource.org *
*                                                       *
* Server started: 12/9/09 3:36 PM                       *
* Server ID: myMule                                     *
* JDK: 1.6.0_15 (mixed mode)                            *
* OS encoding: MacRoman, Mule encoding: UTF-8           *
* OS: Mac OS X (10.6.2, x86_64)                         *
* Host: localhost (127.0.0.1)                           *
*                                                       *
* Agents Running:                                       *
*   Wrapper Manager: Mule PID #0, Wrapper PID #861      *
*   j4p Agent: http://localhost:8899/j4p                *
*   JMX Agent                                           *
*********************************************************

Note the URL for the j4p agent which can be used with jmx4perl or check_jmx4perl like

jmx4perl http://localhost:8899/j4p list

which will result in an output similar to

Mule.myMule:
    Mule.myMule:name=AllStatistics,type=org.mule.Statistics
        Attributes:
            Enabled                             boolean
        Operations:
            void logSummary()
            java.lang.String printXmlSummary()
            java.lang.String printHtmlSummary()
            void clear()
            java.lang.String printCSVSummary()

....
java.lang:
    java.lang:type=Memory
        Attributes:
            NonHeapMemoryUsage                  CompositeData [ro]
            ObjectPendingFinalizationCount      int [ro]
            Verbose                             boolean
            HeapMemoryUsage                     CompositeData [ro]
        Operations:
            void gc()

Note that Mule was started here with a server id myMule (startup option: -M-Dmule.serverId=myMule). As you can see you have access to the Mule specific MBeans and the Java platform MXBeans (which BTW is not easy achievable using Mules JSR-160 agents directly).

For enabling basic security the properties user and password can be set:

<management:custom-agent name="j4p-agent" class="org.jmx4perl.mule.J4pAgent">
  <spring:property name="user" value="roland"/>
  <spring:property name="password" value="wtf"/>
</management:custom-agent>
<management:jmx-server/>

On the client side the options –user and –password can be used with jmx4perl and check_jmx4perl for specifying the credentials.

Finally, all other options as specified as init parameters in j4p.war’s web.xml can be used as properties here as well.