8.2. A Standard MBean Example

This section develops two sample MBean services packaged together in a service archive (.sar).
ConfigServiceMBean interface declares specific methods like the start, getTimeout and stop methods to start, hold and stop the MBean correctly without using any JBoss specific classes. ConfigService class implements ConfigServiceMBean interface and consequently implements the methods used within that interface.
PlainThread class extends ServiceMBeanSupport class and implements PlainThreadMBean interface. PlainThread starts a thread and uses ConfigServiceMBean.getTimeout() to determine how long the thread should sleep.

Example 8.1. Sample MBean services

package org.jboss.example.mbean.support;

public interface ConfigServiceMBean {

    int getTimeout();

    void start();

    void stop();

}

package org.jboss.example.mbean.support;

public class ConfigService implements ConfigServiceMBean {
    int timeout;


    @Override
    public int getTimeout() {
        return timeout;
    }

    @Override
    public void start() {
        //Create a random number between 3000 and 6000 milliseconds
        timeout = (int)Math.round(Math.random() * 3000) + 3000;
        System.out.println("Random timeout set to " + timeout + " seconds");
    }

    @Override
    public void stop() {
        timeout = 0;
    }

}
  
package org.jboss.example.mbean.support;

import org.jboss.system.ServiceMBean;

public interface PlainThreadMBean extends ServiceMBean {
    void setConfigService(ConfigServiceMBean configServiceMBean);
}

package org.jboss.example.mbean.support;

import org.jboss.system.ServiceMBeanSupport;

public class PlainThread extends ServiceMBeanSupport implements PlainThreadMBean {

    private ConfigServiceMBean configService;
    private Thread thread;
    private volatile boolean done;

    @Override
    public void setConfigService(ConfigServiceMBean configService) {
        this.configService = configService;
    }

    @Override
    protected void startService() throws Exception {
        System.out.println("Starting Plain Thread MBean");
        done = false;
        thread = new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    while (!done) {
                        System.out.println("Sleeping....");
                        Thread.sleep(configService.getTimeout());
                        System.out.println("Slept!");
                    }
                } catch (InterruptedException e) {
                    Thread.currentThread().interrupt();
                }
            }
        });
        thread.start();
    }

    @Override
    protected void stopService() throws Exception {
        System.out.println("Stopping Plain Thread MBean");
        done = true;
    }


}
The jboss-service.xml descriptor shows how ConfigService class is injected into PlainThread class using inject tag. The inject tag establishes a dependency between PlainThreadMBean and ConfigServiceMBean and thus allows PlainThreadMBean use ConfigServiceMBean easily.

Example 8.2. JBoss-service.xml Service Descriptor

<server xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="urn:jboss:service:7.0 jboss-service_7_0.xsd"
        xmlns="urn:jboss:service:7.0">
 <mbean code="org.jboss.example.mbean.support.ConfigService" name="jboss.support:name=ConfigBean"/>
 <mbean code="org.jboss.example.mbean.support.PlainThread" name="jboss.support:name=ThreadBean">
  <attribute name="configService">
   <inject bean="jboss.support:name=ConfigBean"/>
  </attribute>
 </mbean>
</server>
After writing the sample MBeans you can package the classes and the jboss-service.xml descriptor in the META-INF folder of a service archive (.sar).
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