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1   /*
2    *  Licensed to the Apache Software Foundation (ASF) under one
3    *  or more contributor license agreements.  See the NOTICE file
4    *  distributed with this work for additional information
5    *  regarding copyright ownership.  The ASF licenses this file
6    *  to you under the Apache License, Version 2.0 (the
7    *  "License"); you may not use this file except in compliance
8    *  with the License.  You may obtain a copy of the License at
9    *  
10   *    http://www.apache.org/licenses/LICENSE-2.0
11   *  
12   *  Unless required by applicable law or agreed to in writing,
13   *  software distributed under the License is distributed on an
14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   *  KIND, either express or implied.  See the License for the
16   *  specific language governing permissions and limitations
17   *  under the License. 
18   *  
19   */
20  package org.apache.directory.mitosis.common;
21  
22  
23  import java.io.Serializable;
24  
25  
26  /**
27   * Represents 'Change Sequence Number' in LDUP specification.
28   * 
29   * A CSN is a composition of a timestamp, a replica ID and a 
30   * operation sequence number.
31   * 
32   * It's described in http://tools.ietf.org/html/draft-sermersheim-ldap-csn-02.
33   * 
34   * The syntax is :
35   * <pre>
36   * ChangeSequenceNumber ::= SEQUENCE {
37   *     time GeneralizedTime,
38   *     timeCount INTEGER (0 ..  MaxInt),
39   *     replicaID UTF8String,
40   *     changeCount INTEGER (0 ..  MaxInt)}
41   * }
42   * </pre>
43   *  
44   * It distinguishes a change made on an object on a server,
45   * and if two operations take place during the same timeStamp,
46   * the operation sequence number makes those operations distinct.
47   * 
48   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
49   */
50  public interface CSN extends Serializable, Comparable<CSN>
51  {
52      /**
53       * Returns GMT timestamp of modification.
54       */
55      long getTimestamp();
56  
57  
58      /**
59       * Returns replica ID.
60       */
61      String getReplicaId();
62  
63  
64      /**
65       * Returns sequence number of modification.
66       */
67      int getOperationSequence();
68  
69  
70      /**
71       * Returns octet-string representation of this CSN. 
72       */
73      String toOctetString();
74  
75  
76      /**
77       * Returns a byte array representing the CSN
78       */
79      byte[] toBytes();
80  }