1 /***
2 * Consumer.java
3 *
4 * This file is part of the creme library.
5 * The creme library intends to ease the development effort of large
6 * applications by providing easy to use support classes.
7 *
8 * Copyright (C) 2002 Denis Bregeon
9 *
10 * This library is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU Lesser General Public
12 * License as published by the Free Software Foundation; either
13 * version 2.1 of the License, or (at your option) any later version.
14 *
15 * This library is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 * Lesser General Public License for more details.
19 *
20 * You should have received a copy of the GNU Lesser General Public
21 * License along with this library; if not, write to the Free Software
22 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 *
24 * contact information: dbregeon@sourceforge.net
25 */
26 package org.jcreme.processing;
27
28 /***
29 * The interface describing the behavior of objects acting as consumers. This
30 * Interface along with the Producer Interface is designed to enable to easily
31 * string "consumption - production" pieces together. It enables to separate the
32 * successive operations applied to data so that the developers can concentrate
33 * their efforts on the operations themselves and not on how they are to be
34 * stringed or how the application will be architectured (distributed producers
35 * and consumers, pools, load balancing...) The architecture issues merely
36 * appear at deployment time.
37 *
38 * @author $Author: dbregeon $
39 * @version $Revision: 1.2 $
40 */
41 public interface Consumer {
42 /***
43 * Sets the producer whose objects the consumer will consume.
44 *
45 * @param provider
46 * The producer to be set.
47 * @throws IllegalArgumentException
48 * In case the type of the given producer doesn't match the
49 * expected type.
50 */
51 void setProvider(Producer provider) throws IllegalArgumentException;
52
53 /***
54 * Returns the producer whose objects the consumer will consume.
55 *
56 * @return The producer whose objects the consumer will consume.
57 */
58 Producer getProvider();
59
60 /***
61 * Consumes a new item from the parent producer.
62 *
63 * @return The next object provided by the parent producer.
64 */
65 Object consumeItem();
66
67 /***
68 * Tells the parent producer that this consumer has finished with this
69 * object.
70 *
71 * @param item
72 * an item that was previously retrieved through the consumeItem
73 * method.
74 * @return true if item was successfully validated. false otherwise.
75 */
76 boolean validateItem(Object item);
77 }
78