1 //******************************************************************************
2 //
3 // File: Message.java
4 // Package: edu.rit.pj.cluster
5 // Unit: Class edu.rit.pj.cluster.Message
6 //
7 // This Java source file is copyright (C) 2006 by Alan Kaminsky. All rights
8 // reserved. For further information, contact the author, Alan Kaminsky, at
9 // ark@cs.rit.edu.
10 //
11 // This Java source file is part of the Parallel Java Library ("PJ"). PJ is free
12 // software; you can redistribute it and/or modify it under the terms of the GNU
13 // General Public License as published by the Free Software Foundation; either
14 // version 3 of the License, or (at your option) any later version.
15 //
16 // PJ is distributed in the hope that it will be useful, but WITHOUT ANY
17 // WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
18 // A PARTICULAR PURPOSE. See the GNU General Public License for more details.
19 //
20 // Linking this library statically or dynamically with other modules is making a
21 // combined work based on this library. Thus, the terms and conditions of the GNU
22 // General Public License cover the whole combination.
23 //
24 // As a special exception, the copyright holders of this library give you
25 // permission to link this library with independent modules to produce an
26 // executable, regardless of the license terms of these independent modules, and
27 // to copy and distribute the resulting executable under terms of your choice,
28 // provided that you also meet, for each linked independent module, the terms
29 // and conditions of the license of that module. An independent module is a module
30 // which is not derived from or based on this library. If you modify this library,
31 // you may extend this exception to your version of the library, but you are not
32 // obligated to do so. If you do not wish to do so, delete this exception
33 // statement from your version.
34 //
35 // A copy of the GNU General Public License is provided in the file gpl.txt. You
36 // may also obtain a copy of the GNU General Public License on the World Wide
37 // Web at http://www.gnu.org/licenses/gpl.html.
38 //
39 //******************************************************************************
40 package edu.rit.pj.cluster;
41
42 import java.io.Externalizable;
43
44 /**
45 * Class Message is the abstract base class for a message sent to a process in
46 * the PJ cluster middleware.
47 *
48 * @author Alan Kaminsky
49 * @version 20-Nov-2006
50 */
51 public abstract class Message
52 implements Externalizable {
53
54 // Exported constants.
55 /**
56 * The message tag for a message from a job backend process.
57 */
58 public static final int FROM_JOB_BACKEND = 1;
59
60 /**
61 * The message tag for a message from a job frontend process.
62 */
63 public static final int FROM_JOB_FRONTEND = 2;
64
65 /**
66 * The message tag for a message from a job launcher process.
67 */
68 public static final int FROM_JOB_LAUNCHER = 3;
69
70 /**
71 * The message tag for a message from a job scheduler process.
72 */
73 public static final int FROM_JOB_SCHEDULER = 4;
74
75 /**
76 * The message tag for a message containing data to write to a file.
77 */
78 public static final int FILE_WRITE_DATA = 5;
79
80 /**
81 * The message tag for a message containing data read from a file.
82 */
83 public static final int FILE_READ_DATA = 6;
84
85 // Hidden data members.
86 private static final long serialVersionUID = -3891573184096499571L;
87
88 private int myTag;
89
90 // Exported constructors.
91 /**
92 * Construct a new message.
93 */
94 public Message() {
95 }
96
97 /**
98 * Construct a new message with the given message tag.
99 *
100 * @param theTag Message tag to use when sending this message.
101 */
102 public Message(int theTag) {
103 myTag = theTag;
104 }
105
106 // Exported operations.
107 /**
108 * Get the message tag to use when sending this message.
109 *
110 * @return Message tag.
111 */
112 public int getTag() {
113 return myTag;
114 }
115
116 }