Files in this tutorial

JMX Resource

The Basic resource

The Basic bean is the example resource implementation. It exposes its managed interface by implementing a BasicMBean interface. The xxxMBean naming convention lets JMX determine which interface to use for management. The MBean interface will expose the Data attribute to JMX.

package example;

public class Basic implements BasicMBean {
  private String _data = "default";

  public void setData(String data)
  {
    _data = data;
  }

  public String getData()
  {
    return _data;
  }
}

BasicMBean is the bean's management interface. It exposes a single attribute, Data, as a getter/setter pair. The name of the interface is important. Since the resource is named Basic, the MBean interface will be named BasicMBean.

package example;

public interface BasicMBean {
  public void setData(String data);

  public String getData();
}

MBean names

MBeans are stored in the MBean server using an ObjectName as its key. Essentially, the MBean server stores the managed beans in a map using the mbean name as a key.

The mbean name consists of a set of <name,value> properties and a "domain" used like a namespace. The properties allow for querying related mbeans. For example, you could request for all mbeans with "J2EEType=Servlet", which would return all the managed servlets.

The example uses the name "example:name=basic". "example" is the domain and the bean's single property is "name" with a value of "basic". By convention, an mbean would normally also have a "type" property, but this example is using a name as simple as possible.

web.xml configuration

The web.xml (or resin.conf) configures the resource with the <resource> tag just as with other resources. The resources is registered as an MBean by specifying an mbean-name.

<web-app xmlns="http://caucho.com/ns/resin">
  <resource mbean-name="example:name=basic" type="example.Basic">
    <init>
      <data>An Example Resource</data>
    </init>
  </resource>
</web-app>

Using the resource proxy

Resin's JMX implementation provides a proxy to managed object using the interface for an API. You can, of course, use the standard JMX interface, the proxy interface is much easier to use.

<%@ page import='com.caucho.jmx.Jmx, example.BasicMBean' %>
<%
BasicMBean basic = (BasicMBean) Jmx.find("example:name=basic");

out.println("data: " + basic.getData());
%>

data: An example resource

Compatibility