001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements. See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership. The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License. You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied. See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 *
019 */
020 package org.apache.directory.shared.ldap.message;
021
022
023 import java.util.Collection;
024
025
026 /**
027 * Represents a referral which is a set of alternative locations where an entry
028 * can be found. Here's what <a href="http://www.faqs.org/rfcs/rfc2251.html">
029 * RFC 2251 </a> has to say about it:
030 *
031 * <pre>
032 * 4.1.11. Referral
033 *
034 * The referral error indicates that the contacted server does not hold
035 * the target entry of the request. The referral field is present in an
036 * LDAPResult if the LDAPResult.resultCode field value is referral, and
037 * absent with all other result codes. It contains a reference to
038 * another server (or set of servers) which may be accessed via LDAP or
039 * other protocols. Referrals can be returned in response to any
040 * operation request (except unbind and abandon which do not have
041 * responses). At least one URL MUST be present in the Referral.
042 *
043 * The referral is not returned for a singleLevel or wholeSubtree search
044 * in which the search scope spans multiple naming contexts, and several
045 * different servers would need to be contacted to complete the
046 * operation. Instead, continuation references, described in section
047 * 4.5.3, are returned.
048 *
049 * Referral ::= SEQUENCE OF LDAPURL -- one or more
050 *
051 * LDAPURL ::= LDAPString -- limited to characters permitted in URLs
052 *
053 * If the client wishes to progress the operation, it MUST follow the
054 * referral by contacting any one of servers. All the URLs MUST be
055 * equally capable of being used to progress the operation. (The
056 * mechanisms for how this is achieved by multiple servers are outside
057 * the scope of this document.)
058 *
059 * URLs for servers implementing the LDAP protocol are written according
060 * to <a href="http://www.faqs.org/rfcs/rfc2255.html">[9]</a>. If an alias
061 * was dereferenced, the <dn> part of the URL MUST be present, with the new
062 * target object name. If the <dn> part is present, the client MUST use this
063 * name in its next request to progress the operation, and if it is not present
064 * the client will use the same name as in the original request. Some servers
065 * (e.g. participating in distributed indexing) may provide a different filter
066 * in a referral for a search operation. If the filter part of the URL
067 * is present in an LDAPURL, the client MUST use this filter in its next
068 * request to progress this search, and if it is not present the client
069 * MUST use the same filter as it used for that search. Other aspects
070 * of the new request may be the same or different as the request which
071 * generated the referral.
072 *
073 * Note that UTF-8 characters appearing in a DN or search filter may not
074 * be legal for URLs (e.g. spaces) and MUST be escaped using the %
075 * method in RFC 1738 <a href="http://www.faqs.org/rfcs/rfc1738.html">[7]</a>.
076 *
077 * Other kinds of URLs may be returned, so long as the operation could
078 * be performed using that protocol.
079 * </pre>
080 *
081 * @author <a href="mailto:dev@directory.apache.org"> Apache Directory Project</a>
082 * @version $Rev: 764131 $
083 * TODO This interface should be located in a url package under common to be
084 * constructed from a LDAPv3 URL parser. The interface will eventually
085 * look very different once url support is added: for one it will add and
086 * remove LdapUrl objects instead of strings or provide both string and
087 * LdapUrl add/remove methods.
088 */
089 public interface InternalReferral
090 {
091 /**
092 * Gets an unmodifiable set of alternative referral urls.
093 *
094 * @return the alternative url objects.
095 */
096 Collection<String> getLdapUrls();
097
098
099 /**
100 * Adds an LDAPv3 URL to this Referral.
101 *
102 * @param a_url
103 * the LDAPv3 URL to add
104 */
105 void addLdapUrl( String url );
106
107
108 /**
109 * Removes an LDAPv3 URL to this Referral.
110 *
111 * @param a_url
112 * the LDAPv3 URL to remove
113 */
114 void removeLdapUrl( String url );
115 }