/*
 * @(#)DirStateFactory.java	1.7 01/12/03
 *
 * Copyright 2002 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
package javax.naming.spi;

import javax.naming.*;
import javax.naming.directory.Attributes;
import java.util.Hashtable;

/**
  * This interface represents a factory for obtaining the state of an
  * object and corresponding attributes for binding.
  *<p>
  * The JNDI framework allows for object implementations to
  * be loaded in dynamically via <tt>object factories</tt>.
  * <p>
  * A <tt>DirStateFactory</tt> extends <tt>StateFactory</tt> 
  * by allowing an <tt>Attributes</tt> instance
  * to be supplied to and be returned by the <tt>getStateToBind()</tt> method.
  * <tt>DirStateFactory</tt> implementations are intended to be used by 
  * <tt>DirContext</tt> service providers.
  * When a caller binds an object using <tt>DirContext.bind()</tt>,
  * he might also specify a set of attributes to be bound with the object.
  * The object and attributes to be bound are passed to 
  * the <tt>getStateToBind()</tt> method of a factory. 
  * If the factory processes the object and attributes, it returns
  * a corresponding pair of object and attributes to be bound.
  * If the factory does not process the object, it must return null.
  *<p>
  * For example, a caller might bind a printer object with some printer-related
  * attributes.
  *<blockquote><pre>
  * ctx.rebind("inky", printer, printerAttrs);
  *</pre></blockquote>
  * An LDAP service provider for <tt>ctx</tt> uses a <tt>DirStateFactory</tt>
  * (indirectly via <tt>DirectoryManager.getStateToBind()</tt>)
  * and gives it <tt>printer</tt> and <tt>printerAttrs</tt>. A factory for
  * an LDAP directory might turn <tt>printer</tt> into a set of attributes
  * and merge that with <tt>printerAttrs</tt>. The service provider then
  * uses the resulting attributes to create an LDAP entry and updates
  * the directory.
  *
  * <p> Since <tt>DirStateFactory</tt> extends <tt>StateFactory</tt>, it
  * has two <tt>getStateToBind()</tt> methods, where one
  * differs from the other by the attributes
  * argument. <tt>DirectoryManager.getStateToBind()</tt> will only use
  * the form that accepts the attributes argument, while
  * <tt>NamingManager.getStateToBind()</tt> will only use the form that
  * does not accept the attributes argument.
  *
  * <p> Either form of the <tt>getStateToBind()</tt> method of a
  * DirStateFactory may be invoked multiple times, possibly using different
  * parameters.  The implementation is thread-safe.
  *
  * @author Rosanna Lee
  * @author Scott Seligman
  * @version 1.7 01/12/03
  *
  * @see DirectoryManager#getStateToBind
  * @see DirObjectFactory
  * @since 1.3
  */
public interface DirStateFactory extends StateFactory {
/**
 * Retrieves the state of an object for binding given the object and attributes
 * to be transformed.
 *<p>
 * <tt>DirectoryManager.getStateToBind()</tt>
 * successively loads in state factories. If a factory implements
 * <tt>DirStateFactory</tt>, <tt>DirectoryManager</tt> invokes this method;
 * otherwise, it invokes <tt>StateFactory.getStateToBind()</tt>.
 * It does this until a factory produces a non-null answer.
 *<p>
 * When an exception is thrown by a factory, 
 * the exception is passed on to the caller
 * of <tt>DirectoryManager.getStateToBind()</tt>. 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 <tt>name</tt>, <tt>inAttrs</tt>, and <tt>environment</tt> 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.
 * The object returned by this method is owned by the caller.
 * The implementation will not subsequently modify it.
 * It will contain either a new <tt>Attributes</tt> object that is
 * likewise owned by the caller, or a reference to the original
 * <tt>inAttrs</tt> parameter.
 *
 * @param obj A possibly 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.
 * @param inAttrs The possibly null attributes to be bound with the object.
 * 	The factory must not modify <tt>inAttrs</tt>.
 * @return A <tt>Result</tt> containing the object's state for binding
 * and the corresponding
 * attributes to be bound; null if the object don't use this factory.
 * @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 DirectoryManager#getStateToBind
 */
    public Result getStateToBind(Object obj, Name name, Context nameCtx,
	Hashtable environment, Attributes inAttrs)
	throws NamingException;


	/**
         * An object/attributes pair for returning the result of 
         * DirStateFactory.getStateToBind().
         */
    public static class Result {
	/**
         * The possibly null object to be bound.
         */
	private Object obj;


	/**
         * The possibly null attributes to be bound.
         */
	private Attributes attrs;

	/**
          * Constructs an instance of Result.
          *
          * @param obj The possibly null object to be bound.
          * @param outAttrs The possibly null attributes to be bound.
          */
	public Result(Object obj, Attributes outAttrs) {
	    this.obj = obj;
	    this.attrs = outAttrs;
	}

	/**
         * Retrieves the object to be bound.
         * @return The possibly null object to be bound.
         */
	public Object getObject() { return obj; };

	/**
         * Retrieves the attributes to be bound.
         * @return The possibly null attributes to be bound.
         */
	public Attributes getAttributes() { return attrs; };

    }
}
