1. /*

  2.  * @(#)NamingEvent.java	1.9 03/01/23

  3.  *

  4.  * Copyright 2003 Sun Microsystems, Inc. All rights reserved.

  5.  * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.

  6.  */

  7. 

  8. package javax.naming.event;

  9. 

  10. import javax.naming.Binding;

  11. 

  12. /**

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

  14.   *<p>

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

  16.   * <ul>

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

  18.   * <li>The event type.

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

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

  21.   * <li>Change information: information about the change

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

  23.   * information.

  24.   * </ul>

  25.   * <p>

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

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

  28.   * Furthermore, the names of the bindings in

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

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

  31.   *<blockquote><pre>

  32.   *	NamespaceChangeListener listener = ...;

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

  34.   *</pre></blockquote>

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

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

  37.   *<blockquote><pre>

  38.   *	evt.getEventContext() == src

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

  40.   *</pre></blockquote>

  41.   *

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

  43.   * <tt>EventContext</tt> concurrently.

  44.   * See the

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

  46.   * for more information on threading issues.

  47.   * 

  48.   * @author Rosanna Lee

  49.   * @author Scott Seligman

  50.   * @version 1.9 03/01/23

  51.   *

  52.   * @see NamingListener

  53.   * @see EventContext

  54.   * @since 1.3

  55.   */

  56. public class NamingEvent extends java.util.EventObject {

  57.     /**

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

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

  60.      */

  61.     public static final int OBJECT_ADDED = 0;

  62. 

  63.     /**

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

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

  66.      */

  67.     public static final int OBJECT_REMOVED = 1;

  68. 

  69.     /**

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

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

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

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

  74.      * the old binding.

  75.      *<p>

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

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

  78.      * has registered.

  79.      *<p>

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

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

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

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

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

  85.      * corresponding provider might not be able to prevent those

  86.      * notifications from being propagated to the listeners.

  87.      *<p>

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

  89.      */

  90.     public static final int OBJECT_RENAMED = 2;

  91. 

  92.     /**

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

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

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

  96.      * modification. For example, the modification might

  97.      * be implemented by first removing the old binding and adding

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

  99.      *<p>

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

  101.      */

  102.     public static final int OBJECT_CHANGED = 3;

  103.     

  104.     /**

  105.      * Contains information about the change that generated this event.

  106.      * @serial

  107.      */

  108.     protected Object changeInfo;

  109.     

  110.     /**

  111.      * Contains the type of this event.

  112.      * @see #OBJECT_ADDED

  113.      * @see #OBJECT_REMOVED

  114.      * @see #OBJECT_RENAMED

  115.      * @see #OBJECT_CHANGED

  116.      * @serial

  117.      */

  118.     protected int type;

  119. 

  120.     /**

  121.      * Contains information about the object before the change.

  122.      * @serial

  123.      */

  124.     protected Binding oldBinding;

  125.     

  126.     /**

  127.      * Contains information about the object after the change.

  128.      * @serial

  129.      */

  130.     protected Binding newBinding;

  131. 

  132.     /**

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

  134.      *<p>

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

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

  137.      *

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

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

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

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

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

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

  144.      *

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

  146.      * @param type The type of the event.

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

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

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

  150.      * @see #OBJECT_ADDED

  151.      * @see #OBJECT_REMOVED

  152.      * @see #OBJECT_RENAMED

  153.      * @see #OBJECT_CHANGED

  154.      */

  155.     public NamingEvent(EventContext source, int type,

  156. 	Binding newBd, Binding oldBd, Object changeInfo) {

  157. 	super(source);

  158. 	this.type = type;

  159. 	oldBinding = oldBd;

  160. 	newBinding = newBd;

  161. 	this.changeInfo = changeInfo;

  162.     }

  163. 

  164.     /**

  165.      * Returns the type of this event.

  166.      * @return The type of this event.

  167.      * @see #OBJECT_ADDED

  168.      * @see #OBJECT_REMOVED

  169.      * @see #OBJECT_RENAMED

  170.      * @see #OBJECT_CHANGED

  171.      */

  172.     public int getType() {

  173. 	return type;

  174.     }

  175. 

  176.     /**

  177.      * Retrieves the event source that fired this event.

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

  179.      *<p>

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

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

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

  183.      * are not guaranteed to be thread-safe

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

  185.      * See the

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

  187.      * for more information on threading issues.

  188.      *

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

  190.      */

  191.     public EventContext getEventContext() {

  192. 	return (EventContext)getSource();

  193.     }

  194. 

  195.     /**

  196.      * Retrieves the binding of the object before the change.

  197.      *<p>

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

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

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

  201.      * <tt>OBJECT_CHANGED</tt>.

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

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

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

  205.      *<p>

  206.      * The name in the binding is to be resolved relative

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

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

  209.      * such information is unavailable.

  210.      *

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

  212.      */

  213.     public Binding getOldBinding() {

  214. 	return oldBinding;

  215.     }

  216. 

  217.     /**

  218.      * Retrieves the binding of the object after the change.

  219.      *<p>

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

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

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

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

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

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

  226.      * is inside the scope after the rename.

  227.      *<p>

  228.      * The name in the binding is to be resolved relative

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

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

  231.      * such information is unavailable.

  232.      *

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

  234.      */

  235.     public Binding getNewBinding() {

  236. 	return newBinding;

  237.     }

  238. 

  239.     /**

  240.      * Retrieves the change information for this event.

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

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

  243.      *

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

  245.      */

  246.     public Object getChangeInfo() {

  247. 	return changeInfo;

  248.     }

  249. 

  250.     /**

  251.      * Invokes the appropriate listener method on this event.

  252.      * The default implementation of

  253.      * this method handles the following event types:

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

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

  256.      *<p>

  257.      * The listener method is executed in the same thread

  258.      * as this method.  See the

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

  260.      * for more information on threading issues.

  261.      * @param listener The nonnull listener.

  262.      */

  263.     public void dispatch(NamingListener listener) {

  264. 	switch (type) {

  265. 	case OBJECT_ADDED:

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

  267. 	    break;

  268. 

  269. 	case OBJECT_REMOVED:

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

  271. 	    break;

  272. 

  273. 	case OBJECT_RENAMED:

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

  275. 	    break;

  276. 

  277. 	case OBJECT_CHANGED:

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

  279. 	    break;

  280. 	}

  281.     }

  282.     private static final long serialVersionUID = -7126752885365133499L;

  283. }