J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 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 | |
| 26 | package javax.naming.spi; |
| 27 | |
| 28 | import java.util.Hashtable; |
| 29 | |
| 30 | import javax.naming.*; |
| 31 | |
| 32 | /** |
| 33 | * This interface represents a factory for creating an object. |
| 34 | *<p> |
| 35 | * The JNDI framework allows for object implementations to |
| 36 | * be loaded in dynamically via <em>object factories</em>. |
| 37 | * For example, when looking up a printer bound in the name space, |
| 38 | * if the print service binds printer names to References, the printer |
| 39 | * Reference could be used to create a printer object, so that |
| 40 | * the caller of lookup can directly operate on the printer object |
| 41 | * after the lookup. |
| 42 | * <p>An <tt>ObjectFactory</tt> is responsible |
| 43 | * for creating objects of a specific type. In the above example, |
| 44 | * you may have a PrinterObjectFactory for creating Printer objects. |
| 45 | *<p> |
| 46 | * An object factory must implement the <tt>ObjectFactory</tt> interface. |
| 47 | * In addition, the factory class must be public and must have a |
| 48 | * public constructor that accepts no parameters. |
| 49 | *<p> |
| 50 | * The <tt>getObjectInstance()</tt> method of an object factory may |
| 51 | * be invoked multiple times, possibly using different parameters. |
| 52 | * The implementation is thread-safe. |
| 53 | *<p> |
| 54 | * The mention of URL in the documentation for this class refers to |
| 55 | * a URL string as defined by RFC 1738 and its related RFCs. It is |
| 56 | * any string that conforms to the syntax described therein, and |
| 57 | * may not always have corresponding support in the java.net.URL |
| 58 | * class or Web browsers. |
| 59 | * |
| 60 | * @author Rosanna Lee |
| 61 | * @author Scott Seligman |
| 62 | * |
| 63 | * @see NamingManager#getObjectInstance |
| 64 | * @see NamingManager#getURLContext |
| 65 | * @see ObjectFactoryBuilder |
| 66 | * @see StateFactory |
| 67 | * @since 1.3 |
| 68 | */ |
| 69 | |
| 70 | public interface ObjectFactory { |
| 71 | /** |
| 72 | * Creates an object using the location or reference information |
| 73 | * specified. |
| 74 | * <p> |
| 75 | * Special requirements of this object are supplied |
| 76 | * using <code>environment</code>. |
| 77 | * An example of such an environment property is user identity |
| 78 | * information. |
| 79 | *<p> |
| 80 | * <tt>NamingManager.getObjectInstance()</tt> |
| 81 | * successively loads in object factories and invokes this method |
| 82 | * on them until one produces a non-null answer. When an exception |
| 83 | * is thrown by an object factory, the exception is passed on to the caller |
| 84 | * of <tt>NamingManager.getObjectInstance()</tt> |
| 85 | * (and no search is made for other factories |
| 86 | * that may produce a non-null answer). |
| 87 | * An object factory should only throw an exception if it is sure that |
| 88 | * it is the only intended factory and that no other object factories |
| 89 | * should be tried. |
| 90 | * If this factory cannot create an object using the arguments supplied, |
| 91 | * it should return null. |
| 92 | *<p> |
| 93 | * A <em>URL context factory</em> is a special ObjectFactory that |
| 94 | * creates contexts for resolving URLs or objects whose locations |
| 95 | * are specified by URLs. The <tt>getObjectInstance()</tt> method |
| 96 | * of a URL context factory will obey the following rules. |
| 97 | * <ol> |
| 98 | * <li>If <code>obj</code> is null, create a context for resolving URLs of the |
| 99 | * scheme associated with this factory. The resulting context is not tied |
| 100 | * to a specific URL: it is able to handle arbitrary URLs with this factory's |
| 101 | * scheme id. For example, invoking <tt>getObjectInstance()</tt> with |
| 102 | * <code>obj</code> set to null on an LDAP URL context factory would return a |
| 103 | * context that can resolve LDAP URLs |
| 104 | * such as "ldap://ldap.wiz.com/o=wiz,c=us" and |
| 105 | * "ldap://ldap.umich.edu/o=umich,c=us". |
| 106 | * <li> |
| 107 | * If <code>obj</code> is a URL string, create an object (typically a context) |
| 108 | * identified by the URL. For example, suppose this is an LDAP URL context |
| 109 | * factory. If <code>obj</code> is "ldap://ldap.wiz.com/o=wiz,c=us", |
| 110 | * getObjectInstance() would return the context named by the distinguished |
| 111 | * name "o=wiz, c=us" at the LDAP server ldap.wiz.com. This context can |
| 112 | * then be used to resolve LDAP names (such as "cn=George") |
| 113 | * relative to that context. |
| 114 | * <li> |
| 115 | * If <code>obj</code> is an array of URL strings, the assumption is that the |
| 116 | * URLs are equivalent in terms of the context to which they refer. |
| 117 | * Verification of whether the URLs are, or need to be, equivalent is up |
| 118 | * to the context factory. The order of the URLs in the array is |
| 119 | * not significant. |
| 120 | * The object returned by getObjectInstance() is like that of the single |
| 121 | * URL case. It is the object named by the URLs. |
| 122 | * <li> |
| 123 | * If <code>obj</code> is of any other type, the behavior of |
| 124 | * <tt>getObjectInstance()</tt> is determined by the context factory |
| 125 | * implementation. |
| 126 | * </ol> |
| 127 | * |
| 128 | * <p> |
| 129 | * The <tt>name</tt> and <tt>environment</tt> parameters |
| 130 | * are owned by the caller. |
| 131 | * The implementation will not modify these objects or keep references |
| 132 | * to them, although it may keep references to clones or copies. |
| 133 | * |
| 134 | * <p> |
| 135 | * <b>Name and Context Parameters.</b> |
| 136 | * <a name=NAMECTX></a> |
| 137 | * |
| 138 | * The <code>name</code> and <code>nameCtx</code> parameters may |
| 139 | * optionally be used to specify the name of the object being created. |
| 140 | * <code>name</code> is the name of the object, relative to context |
| 141 | * <code>nameCtx</code>. |
| 142 | * If there are several possible contexts from which the object |
| 143 | * could be named -- as will often be the case -- it is up to |
| 144 | * the caller to select one. A good rule of thumb is to select the |
| 145 | * "deepest" context available. |
| 146 | * If <code>nameCtx</code> is null, <code>name</code> is relative |
| 147 | * to the default initial context. If no name is being specified, the |
| 148 | * <code>name</code> parameter should be null. |
| 149 | * If a factory uses <code>nameCtx</code> it should synchronize its use |
| 150 | * against concurrent access, since context implementations are not |
| 151 | * guaranteed to be thread-safe. |
| 152 | * <p> |
| 153 | * |
| 154 | * @param obj The possibly null object containing location or reference |
| 155 | * information that can be used in creating an object. |
| 156 | * @param name The name of this object relative to <code>nameCtx</code>, |
| 157 | * or null if no name is specified. |
| 158 | * @param nameCtx The context relative to which the <code>name</code> |
| 159 | * parameter is specified, or null if <code>name</code> is |
| 160 | * relative to the default initial context. |
| 161 | * @param environment The possibly null environment that is used in |
| 162 | * creating the object. |
| 163 | * @return The object created; null if an object cannot be created. |
| 164 | * @exception Exception if this object factory encountered an exception |
| 165 | * while attempting to create an object, and no other object factories are |
| 166 | * to be tried. |
| 167 | * |
| 168 | * @see NamingManager#getObjectInstance |
| 169 | * @see NamingManager#getURLContext |
| 170 | */ |
| 171 | public Object getObjectInstance(Object obj, Name name, Context nameCtx, |
| 172 | Hashtable<?,?> environment) |
| 173 | throws Exception; |
| 174 | } |