1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> 2 <html> 3 <head> 4 <!-- 5 Copyright (c) 1999, 2006, Oracle and/or its affiliates. All rights reserved. 6 DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 7 8 This code is free software; you can redistribute it and/or modify it 9 under the terms of the GNU General Public License version 2 only, as 10 published by the Free Software Foundation. Oracle designates this 11 particular file as subject to the "Classpath" exception as provided 12 by Oracle in the LICENSE file that accompanied this code. 13 14 This code is distributed in the hope that it will be useful, but WITHOUT 15 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 16 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 17 version 2 for more details (a copy is included in the LICENSE file that 18 accompanied this code). 19 20 You should have received a copy of the GNU General Public License version 21 2 along with this work; if not, write to the Free Software Foundation, 22 Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 23 24 Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 25 or visit www.oracle.com if you need additional information or have any 26 questions. 27 --> 28 </head> 29 <body bgcolor="white"> 30 31 Provides the classes and interfaces for accessing naming services. 32 33 <p> 34 This package defines the naming operations of the Java Naming and 35 Directory Interface<font size=-2><sup>TM</sup></font> (JNDI). 36 JNDI provides naming and directory functionality to applications 37 written in the Java programming language. It is designed to be 38 independent of any specific naming or directory service 39 implementation. Thus a variety of services--new, emerging, and 40 already deployed ones--can be accessed in a common way. 41 42 43 <h4>Context</h4> 44 <p> 45 This package defines the notion of a <em>context</em>, represented 46 by the <tt>Context</tt> interface. 47 A context consists of a set of name-to-object <em>bindings</em>. 48 <tt>Context</tt> is the core interface for looking up, binding, unbinding, 49 and renaming objects, and for creating and destroying subcontexts. 50 <p> 51 <tt>lookup()</tt> is the most commonly used operation. 52 You supply <tt>lookup()</tt> 53 the name of the object you want 54 to look up, and it returns the object bound to that name. 55 For example, the following code fragment looks up 56 a printer and sends a document to the printer object 57 to be printed: 58 59 <blockquote> 60 <pre> 61 Printer printer = (Printer)ctx.lookup("treekiller"); 62 printer.print(report); 63 </pre> 64 </blockquote> 65 66 <h4>Names</h4> 67 <p> 68 Every naming method in the <tt>Context</tt> 69 interface has two 70 overloads: one that accepts a 71 <tt>Name</tt> argument and one that accepts a string name. 72 <tt>Name</tt> is an interface that represents a generic 73 name--an ordered sequence of zero of more components. 74 For these methods, <tt>Name</tt> can be used to represent a 75 <em>composite name</em> (<tt>CompositeName</tt>) 76 so that you can name an object using a name which spans multiple namespaces. 77 <p> 78 The overloads that accept <tt>Name</tt> 79 are useful for applications that need to manipulate names: composing 80 them, comparing components, and so on. 81 The overloads that accept string names are likely to be more useful 82 for simple applications, such as those that simply read in a name 83 and look up the corresponding object. 84 <p> 85 86 <h4>Bindings</h4> 87 88 The <tt>Binding</tt> class represents a name-to-object binding. 89 It is a tuple containing the name of the bound object, 90 the name of the object's class, and the object itself. 91 <p> 92 The <tt>Binding</tt> class is actually a subclass of 93 <tt>NameClassPair</tt>, which consists 94 simply of the object's name and the object's class name. 95 The <tt>NameClassPair</tt> is useful when you only want 96 information about the object's class and do not want to 97 pay the extra cost of getting the object. 98 99 <h4>References</h4> 100 Objects are stored in naming and directory services in different ways. 101 If an object store supports storing Java objects, 102 it might support storing an object in its serialized form. 103 However, some naming and directory services do not support the 104 storing of Java objects. Furthermore, for some 105 objects in the directory, Java programs are but one group of applications 106 that access them. In this case, a serialized Java object might 107 not be the most appropriate representation. 108 JNDI defines a <em>reference</em>, represented by the <tt>Reference</tt> 109 class, which contains information on how to construct a copy of the object. 110 JNDI will attempt to turn references looked up from the directory 111 into the Java objects they represent, so that 112 JNDI clients have the illusion that what 113 is stored in the directory are Java objects. 114 115 116 <h4>The Initial Context</h4> 117 118 In JNDI, all naming and directory operations are performed relative 119 to a context. There are no absolute roots. 120 Therefore JNDI defines an <em>initial context</em>, 121 <tt>InitialContext</tt>, 122 which provides a starting point for naming and directory operations. 123 Once you have an initial context, you can use it to 124 look up other contexts and objects. 125 126 <h4>Exceptions</h4> 127 128 JNDI defines a class hierarchy for exceptions that can be thrown in 129 the course of performing naming and directory operations. The root of 130 this class hierarchy is <tt>NamingException</tt>. 131 Programs interested in dealing with a particular exception 132 can catch the corresponding subclass of the exception. 133 Otherwise, programs should catch <tt>NamingException</tt>. 134 135 136 <h2>Package Specification</h2> 137 138 The JNDI API Specification and related documents can be found in the 139 <a href="../../../technotes/guides/jndi/index.html">JNDI documentation</a>. 140 141 @since 1.3 142 143 </body> 144 </html>