| author | ohair |
| Wed, 26 May 2010 20:28:04 -0700 | |
| changeset 5551 | 327690766109 |
| parent 5506 | 202f599c92aa |
| child 23712 | d46a902c1aed |
| permissions | -rw-r--r-- |
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Copyright (c) 1999, 2006, Oracle and/or its affiliates. All rights reserved. |
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DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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This code is free software; you can redistribute it and/or modify it |
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under the terms of the GNU General Public License version 2 only, as |
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published by the Free Software Foundation. Oracle designates this |
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particular file as subject to the "Classpath" exception as provided |
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by Oracle in the LICENSE file that accompanied this code. |
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This code is distributed in the hope that it will be useful, but WITHOUT |
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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version 2 for more details (a copy is included in the LICENSE file that |
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accompanied this code). |
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327690766109
6956202: Fix a few missed rebranding issues, please contact lines etc.
ohair
parents:
5506
diff
changeset
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Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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327690766109
6956202: Fix a few missed rebranding issues, please contact lines etc.
ohair
parents:
5506
diff
changeset
|
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or visit www.oracle.com if you need additional information or have any |
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327690766109
6956202: Fix a few missed rebranding issues, please contact lines etc.
ohair
parents:
5506
diff
changeset
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questions. |
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--> |
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</head> |
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<body bgcolor="white"> |
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Provides support for event notification when accessing naming and |
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directory services. |
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<p> |
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This package defines the event notification operations of the Java Naming |
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and Directory Interface<font size=-2><sup>TM</sup></font> (JNDI). |
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JNDI provides naming and directory functionality to applications |
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written in the Java programming language. It is designed to be |
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independent of any specific naming or directory service |
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implementation. Thus a variety of services--new, emerging, and |
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already deployed ones--can be accessed in a common way. |
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<h4>Naming Events</h4> |
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<p> |
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This package defines a <tt>NamingEvent</tt> class to represent an event |
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that is generated by a naming/directory service. |
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It also defines subinterfaces of <tt>Context</tt> and <tt>DirContext</tt>, |
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called <tt>EventContext</tt> and <tt>EventDirContext</tt>, |
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through which applications can register their interest in events |
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fired by the context. |
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<p> |
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<tt>NamingEvent</tt> represents an event that occurs in a |
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naming or directory service. There are two categories of naming events: |
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<ul> |
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<li>Those that affect the namespace (add/remove/rename an object) |
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<li>Those that affect the objects' contents. |
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</ul> |
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Each category of events is handled by a corresponding listener: |
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<tt>NamespaceChangeListener</tt>, <tt>ObjectChangeListener</tt>. |
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<p> |
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An application, for example, can register its interest in changes to |
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objects in a context as follows: |
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<blockquote> |
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<pre> |
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EventContext src = |
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(EventContext)(new InitialContext()).lookup("o=wiz,c=us");
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src.addNamingListener("ou=users", EventContext.ONELEVEL_SCOPE,
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new ChangeHandler()); |
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... |
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class ChangeHandler implements ObjectChangeListener {
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public void objectChanged(NamingEvent evt) {
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System.out.println(evt.getNewBinding()); |
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} |
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public void namingExceptionThrown(NamingExceptionEvent evt) {
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System.out.println(evt.getException()); |
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} |
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} |
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</pre> |
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</blockquote> |
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<a name=THREADING></a> |
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<h4>Threading Issues</h4> |
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When an event is dispatched to a listener, the listener method (such |
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as <tt>objectChanged()</tt>) may be executed in a thread other than the |
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one in which the call to <tt>addNamingListener()</tt> was executed. |
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The choice of which thread to use is made by the service provider. |
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When an event is dispatched to multiple listeners, the service provider |
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may choose (and is generally encouraged) to execute the listener methods |
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concurrently in separate threads. |
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<p> |
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When a listener instance invokes <tt>NamingEvent.getEventContext()</tt>, |
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it must take into account the possibility that other threads will be |
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working with that context concurrently. Likewise, when a listener is |
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registered via <tt>addNamingListener()</tt>, the registering thread |
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must take into account the likely possibility that the service provider |
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will later invoke the listeners in newly-created threads. As <tt>Context</tt> |
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instances are not guaranteed to be thread-safe in general, all context |
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operations must be synchronized as needed. |
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<h4>Exception Handling</h4> |
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When a listener registers for events with a context, the context might |
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need to do some internal processing in order to collect information |
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required to generate the events. The context, for example, might need |
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to make a request to the server to register interest in changes |
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on the server that will eventually be translated into events. |
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If an exception occurs that prevents information about the events from |
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being collected, the listener will never be notified of the events. |
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When such an exception occurs, a <tt>NamingExceptionEvent</tt> is |
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fired to notify the listener. The listener's |
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<tt>namingExceptionThrown()</tt> method is invoked, as shown in the |
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sample code above, |
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and the listener is automatically deregistered. |
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<p> |
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<h2>Package Specification</h2> |
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The JNDI API Specification and related documents can be found in the |
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<a href="../../../../technotes/guides/jndi/index.html">JNDI documentation</a>. |
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@since 1.3 |
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</body> |
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</html> |