1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.chain;
18
19
20 import java.util.Map;
21
22
23 /**
24 * <p>A {@link Context} represents the state information that is
25 * accessed and manipulated by the execution of a {@link Command} or a
26 * {@link Chain}. Specialized implementations of {@link Context} will
27 * typically add JavaBeans properties that contain typesafe accessors
28 * to information that is relevant to a particular use case for this
29 * context, and/or add operations that affect the state information
30 * that is saved in the context.</p>
31 *
32 * <p>Implementations of {@link Context} must also implement all of the
33 * required and optional contracts of the <code>java.util.Map</code>
34 * interface.</p>
35 *
36 * <p>It is strongly recommended, but not required, that JavaBeans
37 * properties added to a particular {@link Context} implementation exhibit
38 * <em>Attribute-Property Transparency</em>. In other words,
39 * a value stored via a call to <code>setFoo(value)</code> should be visible
40 * by calling <code>get("foo")</code>, and a value stored
41 * via a call to <code>put("foo", value)</code> should be
42 * visible by calling <code>getFoo()</code>. If your {@link Context}
43 * implementation class exhibits this featue, it becomes easier to reuse the
44 * implementation in multiple environments, without the need to cast to a
45 * particular implementation class in order to access the property getter
46 * and setter methods.</p>
47 *
48 * <p>To protect applications from evolution of this interface, specialized
49 * implementations of {@link Context} should generally be created by extending
50 * the provided base class ({@link org.apache.commons.chain.impl.ContextBase})
51 * rather than directly implementing this interface.</p>
52 *
53 * <p>Applications should <strong>NOT</strong> assume that
54 * {@link Context} implementations, or the values stored in its
55 * attributes, may be accessed from multiple threads
56 * simultaneously unless this is explicitly documented for a particular
57 * implementation.</p>
58 *
59 * @author Craig R. McClanahan
60 * @version $Revision: 480477 $ $Date: 2006-11-29 08:34:52 +0000 (Wed, 29 Nov 2006) $
61 */
62
63 public interface Context extends Map {
64
65
66 }