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| */ | |
| /** | |
| * | |
| * Provides support for event notification when accessing naming and | |
| * directory services. | |
| * | |
| * <p> | |
| * This package defines the event notification operations of the Java Naming | |
| * and Directory Interface (JNDI). | |
| * JNDI provides naming and directory functionality to applications | |
| * written in the Java programming language. It is designed to be | |
| * independent of any specific naming or directory service | |
| * implementation. Thus a variety of services--new, emerging, and | |
| * already deployed ones--can be accessed in a common way. | |
| * | |
| * <h2>Naming Events</h2> | |
| * <p> | |
| * This package defines a {@code NamingEvent} class to represent an event | |
| * that is generated by a naming/directory service. | |
| * It also defines subinterfaces of {@code Context} and {@code DirContext}, | |
| * called {@code EventContext} and {@code EventDirContext}, | |
| * through which applications can register their interest in events | |
| * fired by the context. | |
| * <p> | |
| * {@code NamingEvent} represents an event that occurs in a | |
| * naming or directory service. There are two categories of naming events: | |
| * <ul> | |
| * <li>Those that affect the namespace (add/remove/rename an object) | |
| * <li>Those that affect the objects' contents. | |
| * </ul> | |
| * Each category of events is handled by a corresponding listener: | |
| * {@code NamespaceChangeListener}, {@code ObjectChangeListener}. | |
| * <p> | |
| * An application, for example, can register its interest in changes to | |
| * objects in a context as follows: | |
| * {@snippet : | |
| * EventContext src = | |
| * (EventContext)(new InitialContext()).lookup("o=wiz,c=us"); | |
| * src.addNamingListener("ou=users", EventContext.ONELEVEL_SCOPE, | |
| * new ChangeHandler()); | |
| * ... | |
| * class ChangeHandler implements ObjectChangeListener { | |
| * public void objectChanged(NamingEvent evt) { | |
| * System.out.println(evt.getNewBinding()); | |
| * } | |
| * public void namingExceptionThrown(NamingExceptionEvent evt) { | |
| * System.out.println(evt.getException()); | |
| * } | |
| * } | |
| * } | |
| * | |
| * <a id=THREADING></a> | |
| * <h3>Threading Issues</h3> | |
| * | |
| * When an event is dispatched to a listener, the listener method (such | |
| * as {@code objectChanged()}) may be executed in a thread other than the | |
| * one in which the call to {@code addNamingListener()} was executed. | |
| * The choice of which thread to use is made by the service provider. | |
| * When an event is dispatched to multiple listeners, the service provider | |
| * may choose (and is generally encouraged) to execute the listener methods | |
| * concurrently in separate threads. | |
| * <p> | |
| * When a listener instance invokes {@code NamingEvent.getEventContext()}, | |
| * it must take into account the possibility that other threads will be | |
| * working with that context concurrently. Likewise, when a listener is | |
| * registered via {@code addNamingListener()}, the registering thread | |
| * must take into account the likely possibility that the service provider | |
| * will later invoke the listeners in newly-created threads. As {@code Context} | |
| * instances are not guaranteed to be thread-safe in general, all context | |
| * operations must be synchronized as needed. | |
| * | |
| * <h3>Exception Handling</h3> | |
| * | |
| * When a listener registers for events with a context, the context might | |
| * need to do some internal processing in order to collect information | |
| * required to generate the events. The context, for example, might need | |
| * to make a request to the server to register interest in changes | |
| * on the server that will eventually be translated into events. | |
| * If an exception occurs that prevents information about the events from | |
| * being collected, the listener will never be notified of the events. | |
| * When such an exception occurs, a {@code NamingExceptionEvent} is | |
| * fired to notify the listener. The listener's | |
| * {@code namingExceptionThrown()} method is invoked, as shown in the | |
| * sample code above, | |
| * and the listener is automatically deregistered. | |
| * | |
| * <h2>Package Specification</h2> | |
| * | |
| * The JNDI API Specification and related documents can be found in the | |
| * {@extLink jndi_overview JNDI documentation}. | |
| * | |
| * @since 1.3 | |
| */ | |
| package javax.naming.event; |