1/*
2 * Copyright (c) 1999, 2004, Oracle and/or its affiliates. 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.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package javax.naming;
27
28/**
29  * This class represents a Reference whose contents is a name, called the link name,
30  * that is bound to an atomic name in a context.
31  *<p>
32  * The name is a URL, or a name to be resolved relative to the initial
33  * context, or if the first character of the name is ".", the name
34  * is relative to the context in which the link is bound.
35  *<p>
36  * Normal resolution of names in context operations always follow links.
37  * Resolution of the link name itself may cause resolution to pass through
38  * other  links. This gives rise to the possibility of a cycle of links whose
39  * resolution could not terminate normally. As a simple means to avoid such
40  * non-terminating resolutions, service providers may define limits on the
41  * number of links that may be involved in any single operation invoked
42  * by the caller.
43  *<p>
44  * A LinkRef contains a single StringRefAddr, whose type is "LinkAddress",
45  * and whose contents is the link name. The class name field of the
46  * Reference is that of this (LinkRef) class.
47  *<p>
48  * LinkRef is bound to a name using the normal Context.bind()/rebind(), and
49  * DirContext.bind()/rebind(). Context.lookupLink() is used to retrieve the link
50  * itself if the terminal atomic name is bound to a link.
51  *<p>
52  * Many naming systems support a native notion of link that may be used
53  * within the naming system itself. JNDI does not specify whether
54  * there is any relationship between such native links and JNDI links.
55  *<p>
56  * A LinkRef instance is not synchronized against concurrent access by multiple
57  * threads. Threads that need to access a LinkRef instance concurrently should
58  * synchronize amongst themselves and provide the necessary locking.
59  *
60  * @author Rosanna Lee
61  * @author Scott Seligman
62  *
63  * @see LinkException
64  * @see LinkLoopException
65  * @see MalformedLinkException
66  * @see Context#lookupLink
67  * @since 1.3
68  */
69
70  /*<p>
71  * The serialized form of a LinkRef object consists of the serialized
72  * fields of its Reference superclass.
73  */
74
75public class LinkRef extends Reference {
76    /* code for link handling */
77    static final String linkClassName = LinkRef.class.getName();
78    static final String linkAddrType = "LinkAddress";
79
80    /**
81      * Constructs a LinkRef for a name.
82      * @param linkName The non-null name for which to create this link.
83      */
84    public LinkRef(Name linkName) {
85        super(linkClassName, new StringRefAddr(linkAddrType, linkName.toString()));
86    }
87
88    /**
89      * Constructs a LinkRef for a string name.
90      * @param linkName The non-null name for which to create this link.
91      */
92    public LinkRef(String linkName) {
93        super(linkClassName, new StringRefAddr(linkAddrType, linkName));
94    }
95
96    /**
97      * Retrieves the name of this link.
98      *
99      * @return The non-null name of this link.
100      * @exception MalformedLinkException If a link name could not be extracted
101      * @exception NamingException If a naming exception was encountered.
102      */
103    public String getLinkName() throws NamingException {
104        if (className != null && className.equals(linkClassName)) {
105            RefAddr addr = get(linkAddrType);
106            if (addr != null && addr instanceof StringRefAddr) {
107                return (String)((StringRefAddr)addr).getContent();
108            }
109        }
110        throw new MalformedLinkException();
111    }
112    /**
113     * Use serialVersionUID from JNDI 1.1.1 for interoperability
114     */
115    private static final long serialVersionUID = -5386290613498931298L;
116}
117