/*

 * Copyright 1999-2008 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package javax.management;

/**

 * <p>Can be implemented by an MBean in order to

 * carry out operations before and after being registered or unregistered from

 * the MBean Server.  An MBean can also implement this interface in order

 * to get a reference to the MBean Server and/or its name within that

 * MBean Server.</p>

 *

 * <h4 id="injection">Resource injection</h4>

 *

 * <p>As an alternative to implementing {@code MBeanRegistration}, if all that

 * is needed is the MBean Server or ObjectName then an MBean can use

 * <em>resource injection</em>.</p>

 *

 * <p>If a field in the MBean object has type {@link ObjectName} and has

 * the {@link javax.annotation.Resource @Resource} annotation,

 * then the {@code ObjectName} under which the MBean is registered is

 * assigned to that field during registration.  Likewise, if a field has type

 * {@link MBeanServer} and the <code>&#64;Resource</code> annotation, then it will

 * be set to the {@code MBeanServer} in which the MBean is registered.</p>

 *

 * <p>For example:</p>

 *

 * <pre>

 * public Configuration implements ConfigurationMBean {

 *     @Resource

 *     private volatile MBeanServer mbeanServer;

 *     @Resource

 *     private volatile ObjectName objectName;

 *     ...

 *     void unregisterSelf() throws Exception {

 *         mbeanServer.unregisterMBean(objectName);

 *     }

 * }

 * </pre>

 *

 * <p>Resource injection can also be used on fields of type

 * {@link SendNotification} to simplify notification sending.  Such a field

 * will get a reference to an object of type {@code SendNotification} when

 * the MBean is registered, and it can use this reference to send notifications.

 * For example:</p>

 *

 * <pre>

 * public Configuration implements ConfigurationMBean {

 *     @Resource

 *     private volatile SendNotification sender;

 *     ...

 *     private void updated() {

 *         Notification n = new Notification(...);

 *         sender.sendNotification(n);

 *     }

 * }

 * </pre>

 *

 * <p>A field to be injected must not be static.  It is recommended that

 * such fields be declared {@code volatile}.</p>

 *

 * <p>It is also possible to use the <code>&#64;Resource</code> annotation on

 * methods. Such a method must have a {@code void} return type and a single

 * argument of the appropriate type, for example {@code ObjectName}.</p>

 *

 * <p>Any number of fields and methods may have the <code>&#64;Resource</code>

 * annotation.  All fields and methods with type {@code ObjectName}

 * (for example) will receive the same {@code ObjectName} value.</p>

 *

 * <p>Resource injection is available for all types of MBeans, not just

 * Standard MBeans.</p>

 *

 * <p>If an MBean implements the {@link DynamicWrapperMBean} interface then

 * resource injection happens on the object returned by that interface's

 * {@link DynamicWrapperMBean#getWrappedObject() getWrappedObject()} method

 * rather than on the MBean object itself.

 *

 * <p>Resource injection happens after the {@link #preRegister preRegister}

 * method is called (if any), and before the MBean is actually registered

 * in the MBean Server. If a <code>&#64;Resource</code> method throws

 * an exception, the effect is the same as if {@code preRegister} had

 * thrown the exception. In particular it will prevent the MBean from being

 * registered.</p>

 *

 * <p>Resource injection can be used on a field or method where the type

 * is a parent of the injected type, if the injected type is explicitly

 * specified in the <code>&#64;Resource</code> annotation.  For example:</p>

 *

 * <pre>

 *     @Resource(type = MBeanServer.class)

 *     private volatile MBeanServerConnection mbsc;

 * </pre>

 *

 * <p>Formally, suppose <em>R</em> is the type in the <code>&#64;Resource</code>

 * annotation and <em>T</em> is the type of the method parameter or field.

 * Then one of <em>R</em> and <em>T</em> must be a subtype of the other

 * (or they must be the same type).  Injection happens if this subtype

 * is {@code MBeanServer}, {@code ObjectName}, or {@code SendNotification}.

 * Otherwise the <code>&#64;Resource</code> annotation is ignored.</p>

 *

 * <p>Resource injection in MBeans is new in version 2.0 of the JMX API.</p>

 *

 * @since 1.5

 */

public interface MBeanRegistration   {

    /**

     * Allows the MBean to perform any operations it needs before

     * being registered in the MBean Server.  If the name of the MBean

     * is not specified, the MBean can provide a name for its

     * registration.  If any exception is raised, the MBean will not be

     * registered in the MBean Server.

     *

     * @param server The MBean Server in which the MBean will be registered.

     *

     * @param name The object name of the MBean.  This name is null if

     * the name parameter to one of the <code>createMBean</code> or

     * <code>registerMBean</code> methods in the {@link MBeanServer}

     * interface is null.  In that case, this method must return a

     * non-null ObjectName for the new MBean.

     *

     * @return The name under which the MBean is to be registered.

     * This value must not be null.  If the <code>name</code>

     * parameter is not null, it will usually but not necessarily be

     * the returned value.

     *

     * @exception java.lang.Exception This exception will be caught by

     * the MBean Server and re-thrown as an {@link

     * MBeanRegistrationException}.

     */

    public ObjectName preRegister(MBeanServer server,

                                  ObjectName name) throws java.lang.Exception;

    /**

     * Allows the MBean to perform any operations needed after having been

     * registered in the MBean server or after the registration has failed.

     * <p>If the implementation of this method throws a {@link RuntimeException}

     * or an {@link Error}, the MBean Server will rethrow those inside

     * a {@link RuntimeMBeanException} or {@link RuntimeErrorException},

     * respectively. However, throwing an exception in {@code postRegister}

     * will not change the state of the MBean:

     * if the MBean was already registered ({@code registrationDone} is

     * {@code true}), the MBean will remain registered. </p>

     * <p>This might be confusing for the code calling {@code createMBean()}

     * or {@code registerMBean()}, as such code might assume that MBean

     * registration has failed when such an exception is raised.

     * Therefore it is recommended that implementations of

     * {@code postRegister} do not throw Runtime Exceptions or Errors if it

     * can be avoided.</p>

     * @param registrationDone Indicates whether or not the MBean has

     * been successfully registered in the MBean server. The value

     * false means that the registration phase has failed.

     */

    public void postRegister(Boolean registrationDone);

    /**

     * Allows the MBean to perform any operations it needs before

     * being unregistered by the MBean server.

     *

     * @exception java.lang.Exception This exception will be caught by

     * the MBean server and re-thrown as an {@link

     * MBeanRegistrationException}.

     */

    public void preDeregister() throws java.lang.Exception ;

    /**

     * Allows the MBean to perform any operations needed after having been

     * unregistered in the MBean server.

     * <p>If the implementation of this method throws a {@link RuntimeException}

     * or an {@link Error}, the MBean Server will rethrow those inside

     * a {@link RuntimeMBeanException} or {@link RuntimeErrorException},

     * respectively. However, throwing an excepption in {@code postDeregister}

     * will not change the state of the MBean:

     * the MBean was already successfully deregistered and will remain so. </p>

     * <p>This might be confusing for the code calling

     * {@code unregisterMBean()}, as it might assume that MBean deregistration

     * has failed. Therefore it is recommended that implementations of

     * {@code postDeregister} do not throw Runtime Exceptions or Errors if it

     * can be avoided.</p>

     */

    public void postDeregister();

 }