/*

 * Copyright (c) 1999, 2004, Oracle and/or its affiliates. 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.  Oracle designates this

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

 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package javax.naming.spi;

import javax.naming.*;

import java.util.Hashtable;

/**

  * This interface represents a factory for obtaining the state of an

  * object for binding.

  *<p>

  * The JNDI framework allows for object implementations to

  * be loaded in dynamically via <em>object factories</em>.

  * For example, when looking up a printer bound in the name space,

  * if the print service binds printer names to {@code Reference}s, the printer

  * {@code Reference} could be used to create a printer object, so that

  * the caller of lookup can directly operate on the printer object

  * after the lookup.

  * <p>An {@code ObjectFactory} is responsible

  * for creating objects of a specific type.  In the above example,

  * you may have a {@code PrinterObjectFactory} for creating

  * {@code Printer} objects.

  * <p>

  * For the reverse process, when an object is bound into the namespace,

  * JNDI provides <em>state factories</em>.

  * Continuing with the printer example, suppose the printer object is

  * updated and rebound:

  * <blockquote><pre>

  * ctx.rebind("inky", printer);

  * </pre></blockquote>

  * The service provider for {@code ctx} uses a state factory

  * to obtain the state of {@code printer} for binding into its namespace.

  * A state factory for the {@code Printer} type object might return

  * a more compact object for storage in the naming system.

  *<p>

  * A state factory must implement the {@code StateFactory} interface.

  * In addition, the factory class must be public and must have a

  * public constructor that accepts no parameters.

  * Note that in cases where the factory is in a named module then it must be

  * in a package which is exported by that module to the {@code java.naming}

  * module.

  *<p>

  * The {@code getStateToBind()} method of a state factory may

  * be invoked multiple times, possibly using different parameters.

  * The implementation is thread-safe.

  *<p>

  * {@code StateFactory} is intended for use with service providers

  * that implement only the {@code Context} interface.

  * {@code DirStateFactory} is intended for use with service providers

  * that implement the {@code DirContext} interface.

  *

  * @author Rosanna Lee

  * @author Scott Seligman

  *

  * @see NamingManager#getStateToBind

  * @see DirectoryManager#getStateToBind

  * @see ObjectFactory

  * @see DirStateFactory

  * @since 1.3

  */

public interface StateFactory {

/**

 * Retrieves the state of an object for binding.

 *<p>

 * {@code NamingManager.getStateToBind()}

 * successively loads in state factories and invokes this method

 * on them until one produces a non-null answer.

 * {@code DirectoryManager.getStateToBind()}

 * successively loads in state factories.  If a factory implements

 * {@code DirStateFactory}, then {@code DirectoryManager}

 * invokes {@code DirStateFactory.getStateToBind()}; otherwise

 * it invokes {@code StateFactory.getStateToBind()}.

 *<p> When an exception

 * is thrown by a factory, the exception is passed on to the caller

 * of {@code NamingManager.getStateToBind()} and

 * {@code DirectoryManager.getStateToBind()}.

 * The search for other factories

 * that may produce a non-null answer is halted.

 * A factory should only throw an exception if it is sure that

 * it is the only intended factory and that no other factories

 * should be tried.

 * If this factory cannot create an object using the arguments supplied,

 * it should return null.

 * <p>

 * The <code>name</code> and <code>nameCtx</code> parameters may

 * optionally be used to specify the name of the object being created.

 * See the description of "Name and Context Parameters" in

 * {@link ObjectFactory#getObjectInstance ObjectFactory.getObjectInstance()}

 * for details.

 * If a factory uses <code>nameCtx</code> it should synchronize its use

 * against concurrent access, since context implementations are not

 * guaranteed to be thread-safe.

 * <p>

 * The {@code name} and {@code environment} parameters

 * are owned by the caller.

 * The implementation will not modify these objects or keep references

 * to them, although it may keep references to clones or copies.

 *

 * @param obj A non-null object whose state is to be retrieved.

 * @param name The name of this object relative to <code>nameCtx</code>,

 *              or null if no name is specified.

 * @param nameCtx The context relative to which the <code>name</code>

 *              parameter is specified, or null if <code>name</code> is

 *              relative to the default initial context.

 * @param environment The possibly null environment to

 *              be used in the creation of the object's state.

 * @return The object's state for binding;

 *              null if the factory is not returning any changes.

 * @exception NamingException if this factory encountered an exception

 * while attempting to get the object's state, and no other factories are

 * to be tried.

 *

 * @see NamingManager#getStateToBind

 * @see DirectoryManager#getStateToBind

 */

    public Object getStateToBind(Object obj, Name name, Context nameCtx,

                                 Hashtable<?,?> environment)

        throws NamingException;

}