/*

 * Copyright (c) 1999, 2004, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

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 */

package javax.naming;

/**

  * This class represents a Reference whose contents is a name, called the link name,

  * that is bound to an atomic name in a context.

  *<p>

  * The name is a URL, or a name to be resolved relative to the initial

  * context, or if the first character of the name is ".", the name

  * is relative to the context in which the link is bound.

  *<p>

  * Normal resolution of names in context operations always follow links.

  * Resolution of the link name itself may cause resolution to pass through

  * other  links. This gives rise to the possibility of a cycle of links whose

  * resolution could not terminate normally. As a simple means to avoid such

  * non-terminating resolutions, service providers may define limits on the

  * number of links that may be involved in any single operation invoked

  * by the caller.

  *<p>

  * A LinkRef contains a single StringRefAddr, whose type is "LinkAddress",

  * and whose contents is the link name. The class name field of the

  * Reference is that of this (LinkRef) class.

  *<p>

  * LinkRef is bound to a name using the normal Context.bind()/rebind(), and

  * DirContext.bind()/rebind(). Context.lookupLink() is used to retrieve the link

  * itself if the terminal atomic name is bound to a link.

  *<p>

  * Many naming systems support a native notion of link that may be used

  * within the naming system itself. JNDI does not specify whether

  * there is any relationship between such native links and JNDI links.

  *<p>

  * A LinkRef instance is not synchronized against concurrent access by multiple

  * threads. Threads that need to access a LinkRef instance concurrently should

  * synchronize amongst themselves and provide the necessary locking.

  *

  * @author Rosanna Lee

  * @author Scott Seligman

  *

  * @see LinkException

  * @see LinkLoopException

  * @see MalformedLinkException

  * @see Context#lookupLink

  * @since 1.3

  */

  /*<p>

  * The serialized form of a LinkRef object consists of the serialized

  * fields of its Reference superclass.

  */

public class LinkRef extends Reference {

    /* code for link handling */

    static final String linkClassName = LinkRef.class.getName();

    static final String linkAddrType = "LinkAddress";

    /**

      * Constructs a LinkRef for a name.

      * @param linkName The non-null name for which to create this link.

      */

    public LinkRef(Name linkName) {

        super(linkClassName, new StringRefAddr(linkAddrType, linkName.toString()));

    }

    /**

      * Constructs a LinkRef for a string name.

      * @param linkName The non-null name for which to create this link.

      */

    public LinkRef(String linkName) {

        super(linkClassName, new StringRefAddr(linkAddrType, linkName));

    }

    /**

      * Retrieves the name of this link.

      *

      * @return The non-null name of this link.

      * @exception MalformedLinkException If a link name could not be extracted

      * @exception NamingException If a naming exception was encountered.

      */

    public String getLinkName() throws NamingException {

        if (className != null && className.equals(linkClassName)) {

            RefAddr addr = get(linkAddrType);

            if (addr != null && addr instanceof StringRefAddr) {

                return (String)((StringRefAddr)addr).getContent();

            }

        }

        throw new MalformedLinkException();

    }

    /**

     * Use serialVersionUID from JNDI 1.1.1 for interoperability

     */

    private static final long serialVersionUID = -5386290613498931298L;

}