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 }