01: /*
02: * Copyright 2002-2006 the original author or authors.
03: *
04: * Licensed under the Apache License, Version 2.0 (the "License");
05: * you may not use this file except in compliance with the License.
06: * You may obtain a copy of the License at
07: *
08: * http://www.apache.org/licenses/LICENSE-2.0
09: *
10: * Unless required by applicable law or agreed to in writing, software
11: * distributed under the License is distributed on an "AS IS" BASIS,
12: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13: * See the License for the specific language governing permissions and
14: * limitations under the License.
15: */
16:
17: package org.springframework.orm.jdo;
18:
19: import javax.jdo.JDOException;
20: import javax.jdo.PersistenceManager;
21:
22: /**
23: * Callback interface for JDO code. To be used with {@link JdoTemplate}'s
24: * execution methods, often as anonymous classes within a method implementation.
25: * A typical implementation will call PersistenceManager CRUD to perform
26: * some operations on persistent objects.
27: *
28: * <p>Note that JDO works on bytecode-modified Java objects, to be able to
29: * perform dirty detection on each modification of a persistent instance field.
30: * In contrast to Hibernate, using returned objects outside of an active
31: * PersistenceManager poses a problem: To be able to read and modify fields
32: * e.g. in a web GUI, one has to explicitly make the instances "transient".
33: * Reassociation with a new PersistenceManager, e.g. for updates when coming
34: * back from the GUI, isn't possible, as the JDO instances have lost their
35: * identity when turned transient. This means that either value objects have
36: * to be used as parameters, or the contents of the outside-modified instance
37: * have to be copied to a freshly loaded active instance on reassociation.
38: *
39: * @author Juergen Hoeller
40: * @since 03.06.2003
41: * @see JdoTemplate
42: * @see JdoTransactionManager
43: */
44: public interface JdoCallback {
45:
46: /**
47: * Gets called by <code>JdoTemplate.execute</code> with an active JDO
48: * <code>PersistenceManager</code>. Does not need to care about activating
49: * or closing the <code>PersistenceManager</code>, or handling transactions.
50: *
51: * <p>Note that JDO callback code will not flush any modifications to the
52: * database if not executed within a transaction. Thus, you need to make
53: * sure that JdoTransactionManager has initiated a JDO transaction when
54: * the callback gets called, at least if you want to write to the database.
55: *
56: * <p>Allows for returning a result object created within the callback,
57: * i.e. a domain object or a collection of domain objects.
58: * A thrown custom RuntimeException is treated as an application exception:
59: * It gets propagated to the caller of the template.
60: *
61: * @param pm active PersistenceManager
62: * @return a result object, or <code>null</code> if none
63: * @throws JDOException if thrown by the JDO API
64: * @see JdoTemplate#execute
65: * @see JdoTemplate#executeFind
66: */
67: Object doInJdo(PersistenceManager pm) throws JDOException;
68:
69: }
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