src/java.management/share/classes/javax/management/modelmbean/package.html - master - githubmirror/jdk22

src/java.management/share/classes/javax/management/modelmbean/package.html
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Erik Joelsson
8187443: Forest Consolidation: Move files to unified layout
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<title>javax.management.modelmbean package</title>
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    <p>Provides the definition of the ModelMBean classes.  A Model
      MBean is an MBean that acts as a bridge between the management
      interface and the underlying managed resource.  Both the
      management interface and the managed resource are specified as
      Java objects.  The same Model MBean implementation can be
      reused many times with different management interfaces and
      managed resources, and it can provide common functionality
      such as persistence and caching.</p>

    <p>A Model MBean implements the {@link
      javax.management.modelmbean.ModelMBean ModelMBean} interface.
      It is a {@link javax.management.DynamicMBean DynamicMBean}
      whose {@link javax.management.DynamicMBean#getMBeanInfo()
      getMBeanInfo} method returns an object implementing {@link
      javax.management.modelmbean.ModelMBeanInfo
      ModelMBeanInfo}.</p>

    <p>Every MBean has an {@link javax.management.MBeanInfo
      MBeanInfo} with information about the MBean itself, and its
      attributes, operations, constructors, and notifications.  A
      Model MBean augments this <code>MBeanInfo</code> with {@link
      javax.management.Descriptor Descriptor}s that encode
      additional information in the form of (key,value) pairs.
      Usually, <code>Descriptor</code>s are instances of {@link
      javax.management.modelmbean.DescriptorSupport
      DescriptorSupport}.</p>

    <p>The class {@link
      javax.management.modelmbean.RequiredModelMBean
      RequiredModelMBean} provides a standard Model MBean
      implementation.</p>

    <p>The following example shows a Model MBean being used to make
      the <code>get</code> method of a <code>HashMap</code>
      available for management through an MBean server.  No other
      methods are available through the MBean server.  There is
      nothing special about <code>HashMap</code> here.  Public
      methods from any public class can be exposed for management in
      the same way.</p>

    <pre>
import java.lang.reflect.Method;
import java.util.HashMap;
import javax.management.*;
import javax.management.modelmbean.*;

// ...

MBeanServer mbs = MBeanServerFactory.createMBeanServer();
// The MBean Server

HashMap map = new HashMap();
// The resource that will be managed

// Construct the management interface for the Model MBean
Method getMethod = HashMap.class.getMethod("get", new Class[] {Object.class});
ModelMBeanOperationInfo getInfo =
    new ModelMBeanOperationInfo("Get value for key", getMethod);
ModelMBeanInfo mmbi =
    new ModelMBeanInfoSupport(HashMap.class.getName(),
			      "Map of keys and values",
			      null,  // no attributes
			      null,  // no constructors
			      new ModelMBeanOperationInfo[] {getInfo},
			      null); // no notifications

// Make the Model MBean and link it to the resource
ModelMBean mmb = new RequiredModelMBean(mmbi);
mmb.setManagedResource(map, "ObjectReference");

// Register the Model MBean in the MBean Server
ObjectName mapName = new ObjectName(":type=Map,name=whatever");
mbs.registerMBean(mmb, mapName);

// Resource can evolve independently of the MBean
map.put("key", "value");

// Can access the "get" method through the MBean Server
mbs.invoke(mapName, "get", new Object[] {"key"}, new String[] {Object.class.getName()});
// returns "value"
    </pre>

    <h2><a id="spec">Package Specification</a></h2>

    <ul>
	  <li>See the <i>JMX 1.4 Specification</i>
	     <a href="https://jcp.org/aboutJava/communityprocess/mrel/jsr160/index2.html">
             JMX Specification, version 1.4</a>
    </ul>

    @since 1.5

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