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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * under the terms of the GNU General Public License version 2 only, as

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

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 * 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,

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 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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package javax.naming.event;

import javax.naming.Binding;

/**

  * This class represents an event fired by a naming/directory service.

  *<p>

  * The <tt>NamingEvent</tt>'s state consists of

  * <ul>

  * <li>The event source: the <tt>EventContext</tt> which fired this event.

  * <li>The event type.

  * <li>The new binding: information about the object after the change.

  * <li>The old binding: information about the object before the change.

  * <li>Change information: information about the change

  * that triggered this event; usually service provider-specific or server-specific

  * information.

  * </ul>

  * <p>

  * Note that the event source is always the same <tt>EventContext</tt>

  * <em>instance</em>  that the listener has registered with.

  * Furthermore, the names of the bindings in

  * the <tt>NamingEvent</tt> are always relative to that instance.

  * For example, suppose a listener makes the following registration:

  *<blockquote><pre>

  *     NamespaceChangeListener listener = ...;

  *     src.addNamingListener("x", SUBTREE_SCOPE, listener);

  *</pre></blockquote>

  * When an object named "x/y" is subsequently deleted, the corresponding

  * <tt>NamingEvent</tt> (<tt>evt</tt>) must contain:

  *<blockquote><pre>

  *     evt.getEventContext() == src

  *     evt.getOldBinding().getName().equals("x/y")

  *</pre></blockquote>

  *

  * Care must be taken when multiple threads are accessing the same

  * <tt>EventContext</tt> concurrently.

  * See the

  * <a href=package-summary.html#THREADING>package description</a>

  * for more information on threading issues.

  *

  * @author Rosanna Lee

  * @author Scott Seligman

  *

  * @see NamingListener

  * @see EventContext

  * @since 1.3

  */

public class NamingEvent extends java.util.EventObject {

    /**

     * Naming event type for indicating that a new object has been added.

     * The value of this constant is <tt>0</tt>.

     */

    public static final int OBJECT_ADDED = 0;

    /**

     * Naming event type for indicating that an object has been removed.

     * The value of this constant is <tt>1</tt>.

     */

    public static final int OBJECT_REMOVED = 1;

    /**

     * Naming event type for indicating that an object has been renamed.

     * Note that some services might fire multiple events for a single

     * logical rename operation. For example, the rename operation might

     * be implemented by adding a binding with the new name and removing

     * the old binding.

     *<p>

     * The old/new binding in <tt>NamingEvent</tt> may be null if the old

     * name or new name is outside of the scope for which the listener

     * has registered.

     *<p>

     * When an interior node in the namespace tree has been renamed, the

     * topmost node which is part of the listener's scope should used to generate

     * a rename event. The extent to which this can be supported is

     * provider-specific. For example, a service might generate rename

     * notifications for all descendants of the changed interior node and the

     * corresponding provider might not be able to prevent those

     * notifications from being propagated to the listeners.

     *<p>

     * The value of this constant is <tt>2</tt>.

     */

    public static final int OBJECT_RENAMED = 2;

    /**

     * Naming event type for indicating that an object has been changed.

     * The changes might include the object's attributes, or the object itself.

     * Note that some services might fire multiple events for a single

     * modification. For example, the modification might

     * be implemented by first removing the old binding and adding

     * a new binding containing the same name but a different object.

     *<p>

     * The value of this constant is <tt>3</tt>.

     */

    public static final int OBJECT_CHANGED = 3;

    /**

     * Contains information about the change that generated this event.

     * @serial

     */

    protected Object changeInfo;

    /**

     * Contains the type of this event.

     * @see #OBJECT_ADDED

     * @see #OBJECT_REMOVED

     * @see #OBJECT_RENAMED

     * @see #OBJECT_CHANGED

     * @serial

     */

    protected int type;

    /**

     * Contains information about the object before the change.

     * @serial

     */

    protected Binding oldBinding;

    /**

     * Contains information about the object after the change.

     * @serial

     */

    protected Binding newBinding;

    /**

     * Constructs an instance of <tt>NamingEvent</tt>.

     *<p>

     * The names in <tt>newBd</tt> and <tt>oldBd</tt> are to be resolved relative

     * to the event source <tt>source</tt>.

     *

     * For an <tt>OBJECT_ADDED</tt> event type, <tt>newBd</tt> must not be null.

     * For an <tt>OBJECT_REMOVED</tt> event type, <tt>oldBd</tt> must not be null.

     * For an <tt>OBJECT_CHANGED</tt> event type,  <tt>newBd</tt> and

     * <tt>oldBd</tt> must not be null. For  an <tt>OBJECT_RENAMED</tt> event type,

     * one of <tt>newBd</tt> or <tt>oldBd</tt> may be null if the new or old

     * binding is outside of the scope for which the listener has registered.

     *

     * @param source The non-null context that fired this event.

     * @param type The type of the event.

     * @param newBd A possibly null binding before the change. See method description.

     * @param oldBd A possibly null binding after the change. See method description.

     * @param changeInfo A possibly null object containing information about the change.

     * @see #OBJECT_ADDED

     * @see #OBJECT_REMOVED

     * @see #OBJECT_RENAMED

     * @see #OBJECT_CHANGED

     */

    public NamingEvent(EventContext source, int type,

        Binding newBd, Binding oldBd, Object changeInfo) {

        super(source);

        this.type = type;

        oldBinding = oldBd;

        newBinding = newBd;

        this.changeInfo = changeInfo;

    }

    /**

     * Returns the type of this event.

     * @return The type of this event.

     * @see #OBJECT_ADDED

     * @see #OBJECT_REMOVED

     * @see #OBJECT_RENAMED

     * @see #OBJECT_CHANGED

     */

    public int getType() {

        return type;

    }

    /**

     * Retrieves the event source that fired this event.

     * This returns the same object as <tt>EventObject.getSource()</tt>.

     *<p>

     * If the result of this method is used to access the

     * event source, for example, to look up the object or get its attributes,

     * then it needs to be locked  because implementations of <tt>Context</tt>

     * are not guaranteed to be thread-safe

     * (and <tt>EventContext</tt> is a subinterface of <tt>Context</tt>).

     * See the

     * <a href=package-summary.html#THREADING>package description</a>

     * for more information on threading issues.

     *

     * @return The non-null context that fired this event.

     */

    public EventContext getEventContext() {

        return (EventContext)getSource();

    }

    /**

     * Retrieves the binding of the object before the change.

     *<p>

     * The binding must be nonnull if the object existed before the change

     * relative to the source context (<tt>getEventContext()</tt>).

     * That is, it must be nonnull for <tt>OBJECT_REMOVED</tt> and

     * <tt>OBJECT_CHANGED</tt>.

     * For <tt>OBJECT_RENAMED</tt>, it is null if the object before the rename

     * is outside of the scope for which the listener has registered interest;

     * it is nonnull if the object is inside the scope before the rename.

     *<p>

     * The name in the binding is to be resolved relative

     * to the event source <tt>getEventContext()</tt>.

     * The object returned by <tt>Binding.getObject()</tt> may be null if

     * such information is unavailable.

     *

     * @return The possibly null binding of the object before the change.

     */

    public Binding getOldBinding() {

        return oldBinding;

    }

    /**

     * Retrieves the binding of the object after the change.

     *<p>

     * The binding must be nonnull if the object existed after the change

     * relative to the source context (<tt>getEventContext()</tt>).

     * That is, it must be nonnull for <tt>OBJECT_ADDED</tt> and

     * <tt>OBJECT_CHANGED</tt>. For <tt>OBJECT_RENAMED</tt>,

     * it is null if the object after the rename is outside the scope for

     * which the listener registered interest; it is nonnull if the object

     * is inside the scope after the rename.

     *<p>

     * The name in the binding is to be resolved relative

     * to the event source <tt>getEventContext()</tt>.

     * The object returned by <tt>Binding.getObject()</tt> may be null if

     * such information is unavailable.

     *

     * @return The possibly null binding of the object after the change.

     */

    public Binding getNewBinding() {

        return newBinding;

    }

    /**

     * Retrieves the change information for this event.

     * The value of the change information is service-specific. For example,

     * it could be an ID that identifies the change in a change log on the server.

     *

     * @return The possibly null change information of this event.

     */

    public Object getChangeInfo() {

        return changeInfo;

    }

    /**

     * Invokes the appropriate listener method on this event.

     * The default implementation of

     * this method handles the following event types:

     * <tt>OBJECT_ADDED</TT>, <TT>OBJECT_REMOVED</TT>,

     * <TT>OBJECT_RENAMED</TT>, <TT>OBJECT_CHANGED</TT>.

     *<p>

     * The listener method is executed in the same thread

     * as this method.  See the

     * <a href=package-summary.html#THREADING>package description</a>

     * for more information on threading issues.

     * @param listener The nonnull listener.

     */

    public void dispatch(NamingListener listener) {

        switch (type) {

        case OBJECT_ADDED:

            ((NamespaceChangeListener)listener).objectAdded(this);

            break;

        case OBJECT_REMOVED:

            ((NamespaceChangeListener)listener).objectRemoved(this);

            break;

        case OBJECT_RENAMED:

            ((NamespaceChangeListener)listener).objectRenamed(this);

            break;

        case OBJECT_CHANGED:

            ((ObjectChangeListener)listener).objectChanged(this);

            break;

        }

    }

    private static final long serialVersionUID = -7126752885365133499L;

}