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Java > Open Source Codes > jegg > Egg


1 /*
2  * Copyright (c) 2004, Bruce Lowery
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions are met:
7  *
8  * - Redistributions of source code must retain the above copyright notice,
9  * this list of conditions and the following disclaimer.
10  * - Redistributions in binary form must reproduce the above copyright
11  * notice, this list of conditions and the following disclaimer in the
12  * documentation and/or other materials provided with the distribution.
13  * - Neither the name of GOSSIP nor the names of its contributors may be used
14  * to endorse or promote products derived from this software without
15  * specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
18  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
21  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
22  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
23  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
24  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
25  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
26  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
27  * POSSIBILITY OF SUCH DAMAGE.
28  */
29 package jegg;
30
31 /**
32  * The interface that must be implemented by each egg.
33  * <p>
34  * The interface contains methods that the JEgg framework uses to
35  * configure the egg before the first application message is delivered
36  * to the egg. The interface also declares the minimum message interface
37  * handle method that the egg must implement in order to participate in
38  * a JEgg-based application. A typical concrete egg implementation will
39  * implement additional <code>handle</code> methods, one for each distinct
40  * message type that it recognizes. All handle methods take only a single
41  * argument, the message.
42  * </p>
43  * <p>
44  * A convenience base class, jegg.impl.EggBase, may be used instead of
45  * directly implementing the jegg.Egg interface.
46  * </p>
47  */
48 public interface Egg
49 {
50     /**
51      * Set the application context for this egg. This method will be used
52      * by the JEgg framework to configure this egg with its application
53      * context. The application context provides the egg with access the
54      * JEgg framework for use in sending messages, retrieving the message
55      * port of the currently handled message, retrieving configuration
56      * properties, etc.
57      *
58      * @param myContext this eggs application context.
59      */
60     void setContext(final EggContext myContext);
61     
62     /**
63      * Initialize this egg. This method will be invoked by the JEgg framework
64      * before the first application message is delivered to the egg, but
65      * after all of this egg's dependency ports have been delivered to this
66      * egg. A dependency port is a message port belonging to another egg
67      * that this egg needs for use during the processing of messages (i.e.
68      * to send messages to the other egg). The application descriptor is
69      * used to describe to the JEgg framework which other eggs a this egg
70      * will need to send messages to. The ports of those eggs will be
71      * delivered to this egg before the <code>init()</code> method is invoked.
72      *
73      * @throws UnableToInitializeException if this egg cannot complete its
74      * initialization.
75      */
76     void init() throws UnableToInitializeException;
77     
78     /**
79      * The default message handler method. If any message delivered to this
80      * egg has a concrete type for which no other handler method on this
81      * egg can be found, then the message will be delivered to this handler.
82      * <p>
83      * The implementation class should implement additional handler methods,
84      * one for each message type that recognizes.
85      * </p>
86      * @param message a message sent to this egg.
87      */
88     void handle(final Object JavaDoc message);
89 }
90
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