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Java > Open Source Codes > org > opensubsystems > core > persist > DataFactory


1 /*
2  * Copyright (c) 2003 - 2007 OpenSubsystems s.r.o. Slovak Republic. All rights reserved.
3  *
4  * Project: OpenSubsystems
5  *
6  * $Id: DataFactory.java,v 1.8 2007/01/28 06:54:51 bastafidli Exp $
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License as published by
10  * the Free Software Foundation; version 2 of the License.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License
18  * along with this program; if not, write to the Free Software
19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20  */
21
22 package org.opensubsystems.core.persist;
23
24 import org.opensubsystems.core.data.DataObject;
25 import org.opensubsystems.core.error.OSSException;
26
27 /**
28  * Base interface for all data factories responsible for loading and persisting
29  * data. Data factory is here to implement Data Access Object pattern as described
30  * in http://java.sun.com/blueprints/corej2eepatterns/Patterns/DataAccessObject.html
31  * or more generically the Abstract Factory pattern as described in
32  * http://homepage.mac.com/loeffler/java/patterns/absfac.html by GoF95
33  * http://homepage.mac.com/loeffler/java/patterns.html.
34  * It's main purpose is to persist, retrieve and change the persisted data objects
35  * in the underlying persistence store without exposing any persistence store
36  * dependent information to the rest of the application.
37  *
38  * This interface doesn't dictate implementation therefore it is possible
39  * to have FileDataFactory, DatabaseDataFactory, etc.
40  *
41  * @version $Id: DataFactory.java,v 1.8 2007/01/28 06:54:51 bastafidli Exp $
42  * @author Miro Halas
43  * @code.reviewer Miro Halas
44  * @code.reviewed 1.5 2005/03/26 03:49:48 bastafidli
45  */
46 public interface DataFactory
47 {
48    /**
49     * Get data type code for DataObject derived class managed by the data factory
50     * which implements this interface.
51     *
52     * @return int - unique data type code
53     */
54    int getDataType(
55    );
56
57    /**
58     * Get specific data object identified by its id from the persistence store.
59     *
60     * Every data factory has to support this method otherwise we wouldn't have
61     * any way hot to load and test existence of the data.
62     *
63     * @param iId - id of the data object to get, if the id is NEW_ID a new data
64     * object initialized to default values
65     * @param iDomainId - if the data object exists in a domain then by specifying
66     * the domain id it allows the persistance store to limit
67     * the data that will be searched and also possibly
68     * enforce in what domain the id can possibly exist. This
69     * allows to enforce security on the persistance layer
70     * that by ensuring that if the data object doesn't exist
71     * in the domain where it is expected to exist, it will
72     * not be even retrieved. If the data object doesnt exist
73     * in the domain, you can pass DataObject.NEW_ID here
74     * since it won't be used.
75     * @return DataObject - specified data object or null if it couldn't be
76     * retrieved
77     * @throws OSSException - an error while getting data
78     */
79    DataObject get(
80       int iId,
81       int iDomainId
82    ) throws OSSException;
83 }
84
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