KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > org > objectstyle > cayenne > access > DataContextDelegate


1 /* ====================================================================
2  *
3  * The ObjectStyle Group Software License, version 1.1
4  * ObjectStyle Group - http://objectstyle.org/
5  *
6  * Copyright (c) 2002-2005, Andrei (Andrus) Adamchik and individual authors
7  * of the software. All rights reserved.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  *
13  * 1. Redistributions of source code must retain the above copyright
14  * notice, this list of conditions and the following disclaimer.
15  *
16  * 2. Redistributions in binary form must reproduce the above copyright
17  * notice, this list of conditions and the following disclaimer in
18  * the documentation and/or other materials provided with the
19  * distribution.
20  *
21  * 3. The end-user documentation included with the redistribution, if any,
22  * must include the following acknowlegement:
23  * "This product includes software developed by independent contributors
24  * and hosted on ObjectStyle Group web site (http://objectstyle.org/)."
25  * Alternately, this acknowlegement may appear in the software itself,
26  * if and wherever such third-party acknowlegements normally appear.
27  *
28  * 4. The names "ObjectStyle Group" and "Cayenne" must not be used to endorse
29  * or promote products derived from this software without prior written
30  * permission. For written permission, email
31  * "andrus at objectstyle dot org".
32  *
33  * 5. Products derived from this software may not be called "ObjectStyle"
34  * or "Cayenne", nor may "ObjectStyle" or "Cayenne" appear in their
35  * names without prior written permission.
36  *
37  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40  * DISCLAIMED. IN NO EVENT SHALL THE OBJECTSTYLE GROUP OR
41  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48  * SUCH DAMAGE.
49  * ====================================================================
50  *
51  * This software consists of voluntary contributions made by many
52  * individuals and hosted on ObjectStyle Group web site. For more
53  * information on the ObjectStyle Group, please see
54  * <http://objectstyle.org/>.
55  */
56
57 package org.objectstyle.cayenne.access;
58
59 import org.objectstyle.cayenne.DataObject;
60 import org.objectstyle.cayenne.DataRow;
61 import org.objectstyle.cayenne.query.GenericSelectQuery;
62
63 /**
64  * Defines API for a DataContext "delegate" - an object that is temporarily passed control
65  * by DataContext at some critical points in the normal flow of execution. A delegate thus can
66  * modify the flow, abort an operation, modify the objects participating in an operation,
67  * or perform any other tasks it deems necessary. DataContextDelegate is shared by DataContext
68  * and its ObjectStore.
69  *
70  * @see org.objectstyle.cayenne.access.DataContext
71  *
72  * @author Mike Kienenberger
73  * @author Andrus Adamchik
74  *
75  * @since 1.1
76  */
77 public interface DataContextDelegate {
78     
79     /**
80      * Invoked before a <code>GenericSelectQuery</code> is executed. The delegate
81      * may modify the <code>GenericSelectQuery</code> by returning a different
82      * <code>GenericSelectQuery</code>, or may return null to discard the query.
83      *
84      * @return the original or modified <code>GenericSelectQuery</code> or null to discard the query.
85      */
86     public GenericSelectQuery willPerformSelect(DataContext context, GenericSelectQuery query);
87
88     /**
89      * Invoked by parent DataContext whenever an object change is detected.
90      * This can be a change to the object snapshot, or a modification of an "independent"
91      * relationship not resulting in a snapshot change. In the later case snapshot
92      * argument may be null. If a delegate returns <code>true</code>, ObjectStore
93      * will attempt to merge the changes into an object.
94      */
95     public boolean shouldMergeChanges(DataObject object, DataRow snapshotInStore);
96     
97     /**
98      * Called after a successful merging of external changes to an object.
99      * If previosly a delegate returned <code>false</code> from
100      * {@link #shouldMergeChanges(DataObject, DataRow)}, this method
101      * is not invoked, since changes were not merged.
102      */
103     public void finishedMergeChanges(DataObject object);
104     
105     /**
106      * Invoked by ObjectStore whenever it is detected that a database
107      * row was deleted for object. If a delegate returns <code>true</code>,
108      * ObjectStore will change MODIFIED objects to NEW (resulting in recreating the
109      * deleted record on next commit) and all other objects - to TRANSIENT.
110      * To block this behavior, delegate should return <code>false</code>, and
111      * possibly do its own processing.
112      *
113      * @param object DataObject that was deleted externally and is still present
114      * in the ObjectStore associated with the delegate.
115      */
116     public boolean shouldProcessDelete(DataObject object);
117     
118     /**
119      * Called after a successful processing of externally deleted object.
120      * If previosly a delegate returned <code>false</code> from
121      * {@link #shouldProcessDelete(DataObject)}, this method
122      * is not invoked, since no processing was done.
123      */
124     public void finishedProcessDelete(DataObject object);
125 }
126
127
Popular Tags