1 /*
2 * Copyright 1999-2004 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25 package javax.naming.spi;
26
27 import javax.naming;
28 import java.util.Hashtable;
29
30 /**
31 * This interface represents a factory for obtaining the state of an
32 * object for binding.
33 *<p>
34 * The JNDI framework allows for object implementations to
35 * be loaded in dynamically via <em>object factories</em>.
36 * For example, when looking up a printer bound in the name space,
37 * if the print service binds printer names to <tt>Reference</tt>s, the printer
38 * <tt>Reference</tt> could be used to create a printer object, so that
39 * the caller of lookup can directly operate on the printer object
40 * after the lookup.
41 * <p>An <tt>ObjectFactory</tt> is responsible
42 * for creating objects of a specific type. In the above example,
43 * you may have a <tt>PrinterObjectFactory</tt> for creating
44 * <tt>Printer</tt> objects.
45 * <p>
46 * For the reverse process, when an object is bound into the namespace,
47 * JNDI provides <em>state factories</em>.
48 * Continuing with the printer example, suppose the printer object is
49 * updated and rebound:
50 * <blockquote><pre>
51 * ctx.rebind("inky", printer);
52 * </pre></blockquote>
53 * The service provider for <tt>ctx</tt> uses a state factory
54 * to obtain the state of <tt>printer</tt> for binding into its namespace.
55 * A state factory for the <tt>Printer</tt> type object might return
56 * a more compact object for storage in the naming system.
57 *<p>
58 * A state factory must implement the <tt>StateFactory</tt> interface.
59 * In addition, the factory class must be public and must have a
60 * public constructor that accepts no parameters.
61 *<p>
62 * The <tt>getStateToBind()</tt> method of a state factory may
63 * be invoked multiple times, possibly using different parameters.
64 * The implementation is thread-safe.
65 *<p>
66 * <tt>StateFactory</tt> is intended for use with service providers
67 * that implement only the <tt>Context</tt> interface.
68 * <tt>DirStateFactory</tt> is intended for use with service providers
69 * that implement the <tt>DirContext</tt> interface.
70 *
71 * @author Rosanna Lee
72 * @author Scott Seligman
73 *
74 * @see NamingManager#getStateToBind
75 * @see DirectoryManager#getStateToBind
76 * @see ObjectFactory
77 * @see DirStateFactory
78 * @since 1.3
79 */
80 public interface StateFactory {
81 /**
82 * Retrieves the state of an object for binding.
83 *<p>
84 * <tt>NamingManager.getStateToBind()</tt>
85 * successively loads in state factories and invokes this method
86 * on them until one produces a non-null answer.
87 * <tt>DirectoryManager.getStateToBind()</tt>
88 * successively loads in state factories. If a factory implements
89 * <tt>DirStateFactory</tt>, then <tt>DirectoryManager</tt>
90 * invokes <tt>DirStateFactory.getStateToBind()</tt>; otherwise
91 * it invokes <tt>StateFactory.getStateToBind()</tt>.
92 *<p> When an exception
93 * is thrown by a factory, the exception is passed on to the caller
94 * of <tt>NamingManager.getStateToBind()</tt> and
95 * <tt>DirectoryManager.getStateToBind()</tt>.
96 * The search for other factories
97 * that may produce a non-null answer is halted.
98 * A factory should only throw an exception if it is sure that
99 * it is the only intended factory and that no other factories
100 * should be tried.
101 * If this factory cannot create an object using the arguments supplied,
102 * it should return null.
103 * <p>
104 * The <code>name</code> and <code>nameCtx</code> parameters may
105 * optionally be used to specify the name of the object being created.
106 * See the description of "Name and Context Parameters" in
107 * {@link ObjectFactory#getObjectInstance ObjectFactory.getObjectInstance()}
108 * for details.
109 * If a factory uses <code>nameCtx</code> it should synchronize its use
110 * against concurrent access, since context implementations are not
111 * guaranteed to be thread-safe.
112 * <p>
113 * The <tt>name</tt> and <tt>environment</tt> parameters
114 * are owned by the caller.
115 * The implementation will not modify these objects or keep references
116 * to them, although it may keep references to clones or copies.
117 *
118 * @param obj A non-null object whose state is to be retrieved.
119 * @param name The name of this object relative to <code>nameCtx</code>,
120 * or null if no name is specified.
121 * @param nameCtx The context relative to which the <code>name</code>
122 * parameter is specified, or null if <code>name</code> is
123 * relative to the default initial context.
124 * @param environment The possibly null environment to
125 * be used in the creation of the object's state.
126 * @return The object's state for binding;
127 * null if the factory is not returning any changes.
128 * @exception NamingException if this factory encountered an exception
129 * while attempting to get the object's state, and no other factories are
130 * to be tried.
131 *
132 * @see NamingManager#getStateToBind
133 * @see DirectoryManager#getStateToBind
134 */
135 public Object getStateToBind(Object obj, Name name, Context nameCtx,
136 Hashtable<?,?> environment)
137 throws NamingException;
138 }
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