1 /*
2 * $Source$
3 * $Revision$
4 *
5 * Copyright (C) 2001 William Chesters
6 *
7 * Part of Melati (http://melati.org), a framework for the rapid
8 * development of clean, maintainable web applications.
9 *
10 * Melati is free software; Permission is granted to copy, distribute
11 * and/or modify this software under the terms either:
12 *
13 * a) the GNU General Public License as published by the Free Software
14 * Foundation; either version 2 of the License, or (at your option)
15 * any later version,
16 *
17 * or
18 *
19 * b) any version of the Melati Software License, as published
20 * at http://melati.org
21 *
22 * You should have received a copy of the GNU General Public License and
23 * the Melati Software License along with this program;
24 * if not, write to the Free Software Foundation, Inc.,
25 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA to obtain the
26 * GNU General Public License and visit http://melati.org to obtain the
27 * Melati Software License.
28 *
29 * Feel free to contact the Developers of Melati (http://melati.org),
30 * if you would like to work out a different arrangement than the options
31 * outlined here. It is our intention to allow Melati to be used by as
32 * wide an audience as possible.
33 *
34 * This program is distributed in the hope that it will be useful,
35 * but WITHOUT ANY WARRANTY; without even the implied warranty of
36 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
37 * GNU General Public License for more details.
38 *
39 * Contact details for copyright holder:
40 *
41 * William Chesters <williamc@paneris.org>
42 * http://paneris.org/~williamc
43 * Obrechtstraat 114, 2517VX Den Haag, The Netherlands
44 */
45 package org.melati.poem;
46
47 import java.util.Enumeration;
48 import java.util.Map;
49
50 /**
51 * Class representing what to do about references to a {@link Persistent}
52 * which is about to be deleted.
53 *
54 * Three canned {@link IntegrityFix} policies are provided: {@link
55 * StandardIntegrityFix#delete}, which simply deletes all referring objects,
56 * {@link StandardIntegrityFix#clear}, which <TT>NULL</TT>s out all
57 * references, and {@link StandardIntegrityFix#prevent}, which prevents
58 * deletion if there are any references which would be left dangling.
59 *
60 * @author WilliamC At paneris.org
61 *
62 */
63
64 public interface IntegrityFix {
65
66 /**
67 * Do something about references from a given column to a
68 * {@link Persistent} which is about to be deleted. Called via {@link
69 * Persistent#delete(Map)}, this gives the application programmer
70 * fine-grained control over how referential integrity is maintained.
71 *
72 *
73 * @param referee The object which is about to be deleted.
74
75 * @param column A column which refers to <TT>referee</TT>'s table:
76 * <TT>column.getType()</TT> is a
77 * <TT>ReferencePoemType</TT> with <TT>targetTable()</TT>
78 * <TT>==</TT> <TT>referee.getTable()</TT>.
79 *
80 * @param refs All the <TT>Persistent</TT>s of which <TT>column</TT>
81 * actually points to <TT>referee</TT>.
82 *
83 * @param referenceFixOfColumn The column-to-<TT>IntegrityFix</TT>
84 * mapping passed into {@link Persistent#delete(Map)}.
85 *
86 * @return Either a list of the <TT>Persistent</TT>s from <TT>refs</TT> which
87 * constitute reasons why the <TT>referee</TT> can't be deleted
88 * or the <TT>EmptyEnumeration</TT> if there are no references or
89 * all <TT>refs</TT> have been cleared or deleted.
90 */
91
92 Enumeration<Persistent> referencesTo(Persistent referee, Column<?> column,
93 Enumeration<Persistent> refs, Map<Column<?>, IntegrityFix> referenceFixOfColumn);
94
95 /**
96 * Integrity fixes are set in the DSD by name.
97 * @return the name
98 */
99 String getName();
100 }