SimpleStandard.java

/*
 * Copyright (c) 2003, 2008, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/**
 * Simple definition of a standard MBean, named "SimpleStandard".
 *
 * The "SimpleStandard" standard MBean shows how to expose attributes and
 * operations for management by implementing its corresponding
 * "SimpleStandardMBean" management interface.
 *
 * This MBean has two attributes and one operation exposed
 * for management by a JMX agent:
 *      - the read/write "State" attribute,
 *      - the read only "NbChanges" attribute,
 *      - the "reset()" operation.
 *
 * This object also has one property and one method not exposed
 * for management by a JMX agent:
 *      - the "NbResets" property,
 *      - the "getNbResets()" method.
 */

import java.security.AccessControlContext;
import java.security.AccessController;
import java.security.Principal;
import java.util.Set;
import javax.management.AttributeChangeNotification;
import javax.management.NotificationBroadcasterSupport;
import javax.management.remote.JMXPrincipal;
import javax.security.auth.Subject;

public class SimpleStandard
    extends NotificationBroadcasterSupport
    implements SimpleStandardMBean {

    /*
     * -----------------------------------------------------
     * CONSTRUCTORS
     * -----------------------------------------------------
     */

    public SimpleStandard(String principalName) {
        this.principalName = principalName;
    }

    /*
     * -----------------------------------------------------
     * IMPLEMENTATION OF THE SimpleStandardMBean INTERFACE
     * -----------------------------------------------------
     */

    /**
     * Getter: get the "State" attribute of the "SimpleStandard" standard MBean.
     *
     * @return the current value of the "State" attribute.
     */
    public String getState() {
        checkSubject("getState");
        return state;
    }

    /**
     * Setter: set the "State" attribute of the "SimpleStandard" standard MBean.
     *
     * @param <VAR>s</VAR> the new value of the "State" attribute.
     */
    public void setState(String s) {
        checkSubject("setState");
        state = s;
        nbChanges++;
    }

    /**
     * Getter: get the "NbChanges" attribute of the "SimpleStandard" standard
     * MBean.
     *
     * @return the current value of the "NbChanges" attribute.
     */
    public int getNbChanges() {
        checkSubject("getNbChanges");
        return nbChanges;
    }

    /**
     * Operation: reset to their initial values the "State" and "NbChanges"
     * attributes of the "SimpleStandard" standard MBean.
     */
    public void reset() {
        checkSubject("reset");
        AttributeChangeNotification acn =
            new AttributeChangeNotification(this,
                                            0,
                                            0,
                                            "NbChanges reset",
                                            "NbChanges",
                                            "Integer",
                                            new Integer(nbChanges),
                                            new Integer(0));
        state = "initial state";
        nbChanges = 0;
        nbResets++;
        sendNotification(acn);
    }

    /*
     * -----------------------------------------------------
     * METHOD NOT EXPOSED FOR MANAGEMENT BY A JMX AGENT
     * -----------------------------------------------------
     */

    /**
     * Return the "NbResets" property.
     * This method is not a Getter in the JMX sense because
     * it is not exposed in the "SimpleStandardMBean" interface.
     *
     * @return the current value of the "NbResets" property.
     */
    public int getNbResets() {
        return nbResets;
    }

    /*
     * ---------------
     * PRIVATE METHODS
     * ---------------
     */

    /**
     * Check that the principal contained in the Subject is of
     * type JMXPrincipal and refers to the principalName identity.
     */
    private void checkSubject(String op) {
        AccessControlContext acc = AccessController.getContext();
        Subject subject = Subject.getSubject(acc);
        Set principals = subject.getPrincipals();
        Principal principal = (Principal) principals.iterator().next();
        if (!(principal instanceof JMXPrincipal))
            throw new SecurityException(op+": Authenticated subject contains " +
                                        "invalid principal type = " +
                                        principal.getClass().getName());
        String identity = principal.getName();
        if (!identity.equals(principalName))
            throw new SecurityException(op+": Authenticated subject contains " +
                                        "invalid principal name = " + identity);
    }

    /*
     * -----------------------------------------------------
     * ATTRIBUTES ACCESSIBLE FOR MANAGEMENT BY A JMX AGENT
     * -----------------------------------------------------
     */

    private String state = "initial state";
    private int nbChanges = 0;

    /*
     * -----------------------------------------------------
     * PROPERTY NOT ACCESSIBLE FOR MANAGEMENT BY A JMX AGENT
     * -----------------------------------------------------
     */

    private int nbResets = 0;
    private String principalName;
}