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Java > Open Source Codes > org > apache > ojb > broker > util > sequence > SequenceManager


1 package org.apache.ojb.broker.util.sequence;
2
3 /* Copyright 2002-2005 The Apache Software Foundation
4  *
5  * Licensed under the Apache License, Version 2.0 (the "License");
6  * you may not use this file except in compliance with the License.
7  * You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  */
17
18 import org.apache.ojb.broker.accesslayer.JdbcAccess;
19 import org.apache.ojb.broker.metadata.ClassDescriptor;
20 import org.apache.ojb.broker.metadata.FieldDescriptor;
21
22 /**
23  * SequenceManagers are responsible for creating new unique
24  * ID's - unique accross all "extent" object declarations in OJB metadata.
25  * There are some standard sequence manager implementations in
26  * this package.
27  * <p/>
28  * SequenceManager objects are obtained from a factory class called
29  * {@link SequenceManagerFactory}.
30  * This Factory can be configured to provide instances of user defined
31  * implementors of this interface.
32  * <p/>
33  * NOTE: SequenceManagers should be aware of "extents" ("extent" is an OJB inheritance feature),
34  * that is: if you ask for an uid for an Interface (more exact for one implementor class)
35  * with several implementor classes, or a baseclass with several subclasses the returned uid
36  * should be unique accross all tables representing objects of the extent in question.
37  *
38  * @version $Id: SequenceManager.java,v 1.10.2.6 2005/12/21 22:28:41 tomdz Exp $
39  */
40 public interface SequenceManager
41 {
42     /**
43      * This method is called to get an unique value <strong>before</strong> the object
44      * is written to persistent storage.
45      * <br/>
46      * Returns a unique object for the given field attribute.
47      * The returned value takes in account the jdbc-type
48      * and the FieldConversion.sql2java() conversion defined for <code>field</code>.
49      * The returned object is unique accross all tables of "extent" classes the
50      * field belongs to.
51      * <br/>
52      * Implementations using native identity columns should return a unique
53      * incremented counter object for temporary use by OJB.
54      */
55     public Object JavaDoc getUniqueValue(FieldDescriptor field) throws SequenceManagerException;
56
57     /**
58      * This method is called <strong>after</strong> the object was written to the persistent storage.
59      * <br/>
60      * This is to support native Identity columns (auto_increment columns) on the db side.
61      * Other implementations may ignore this method.
62      * @param dbAccess Current used {@link org.apache.ojb.broker.accesslayer.JdbcAccess} instance
63      * @param cld Descriptor for specified object
64      * @param obj The object to associate with identity value
65      */
66     public void afterStore(JdbcAccess dbAccess, ClassDescriptor cld, Object JavaDoc obj) throws SequenceManagerException;
67 }
68
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