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Java > Open Source Codes > com > db4o > replication > ReplicationProcess


1 /* Copyright (C) 2004 - 2006 db4objects Inc. http://www.db4o.com
2
3 This file is part of the db4o open source object database.
4
5 db4o is free software; you can redistribute it and/or modify it under
6 the terms of version 2 of the GNU General Public License as published
7 by the Free Software Foundation and as clarified by db4objects' GPL
8 interpretation policy, available at
9 http://www.db4o.com/about/company/legalpolicies/gplinterpretation/
10 Alternatively you can write to db4objects, Inc., 1900 S Norfolk Street,
11 Suite 350, San Mateo, CA 94403, USA.
12
13 db4o is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
17
18 You should have received a copy of the GNU General Public License along
19 with this program; if not, write to the Free Software Foundation, Inc.,
20 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
21 package com.db4o.replication;
22
23 import com.db4o.*;
24 import com.db4o.query.*;
25
26
27 /**
28  * db4o replication interface.
29  *
30  * @see com.db4o.ext.ExtObjectContainer#replicationBegin(ObjectContainer, ReplicationConflictHandler)
31  */
32 public interface ReplicationProcess {
33     
34     /**
35      * checks if an object has been modified in both ObjectContainers involved
36      * in the replication process since the last time the two ObjectContainers
37      * were replicated.
38      * @param obj - the object to check for a conflict.
39      */
40     public void checkConflict(Object JavaDoc obj);
41     
42     /**
43      * commits the replication task to both involved ObjectContainers.
44      * <br><br>Call this method after replication is completed to
45      * write all changes back to the database files. This method
46      * synchronizes both ObjectContainers by setting the transaction
47      * serial number (@link ExtObjectContainer#version()) on both
48      * ObjectContainers to be equal
49      * to the higher version number among the two. A record with
50      * information about this replication task, including the
51      * synchronized version number is stored to both ObjectContainers
52      * to allow future incremental replication.
53      */
54     public void commit();
55     
56     /**
57      * returns the "peerA" ObjectContainer involved in this ReplicationProcess.
58      */
59     public ObjectContainer peerA();
60     
61     
62     /**
63      * returns the "peerB" ObjectContainer involved in this ReplicationProcess.
64      */
65     public ObjectContainer peerB();
66     
67     
68     /**
69      * replicates an object.
70      * <br><br>By default the version number of the object is checked in
71      * both ObjectContainers involved in the replication process. If the
72      * version number has not changed since the last time the two
73      * ObjectContainers were replicated
74      * @param obj
75      */
76     public void replicate(Object JavaDoc obj);
77     
78     /**
79      * ends a replication task without committing any changes.
80      */
81     public void rollback();
82     
83     /**
84      * modifies the replication policy, what to do on a call to {@link #replicate(Object)}.
85      * <br><br>If no direction is set, the replication process will be bidirectional by
86      * default.
87      * @param relicateFrom the ObjectContainer to replicate from
88      * @param replicateTo the ObjectContainer to replicate to
89      */
90     public void setDirection(ObjectContainer relicateFrom, ObjectContainer replicateTo);
91
92     /**
93      * adds a constraint to the passed Query to query only for objects that
94      * were modified since the last replication process between the two
95      * ObjectContainers involved in this replication process.
96      * @param query the Query to be constrained
97      */
98     public void whereModified(Query query);
99     
100
101 }
102
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