MessageConsumer


1   /*
2    * Copyright (C) 2001 - 2003 ScalAgent Distributed Technologies
3    * Copyright (C) 1996 - 2000 BULL
4    * Copyright (C) 1996 - 2000 INRIA
5    *
6    * This library is free software; you can redistribute it and/or
7    * modify it under the terms of the GNU Lesser General Public
8    * License as published by the Free Software Foundation; either
9    * version 2.1 of the License, or any later version.
10   * 
11   * This library is distributed in the hope that it will be useful,
12   * but WITHOUT ANY WARRANTY; without even the implied warranty of
13   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14   * Lesser General Public License for more details.
15   * 
16   * You should have received a copy of the GNU Lesser General Public
17   * License along with this library; if not, write to the Free Software
18   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
19   * USA.
20   */
21  package fr.dyade.aaa.agent;
22  
23  import java.io.IOException  ;
24  /**
25   * The parent interface for all messages consumers.
26   * 
27   * @see     Engine, Network.
28   */
29  public interface MessageConsumer {
30    /**
31     * Returns this <code>MessageConsumer</code>'s name.
32     *
33     * @return this <code>MessageConsumer</code>'s name.
34     */
35    String   getName();
36  
37    /**
38     * Returns the corresponding domain's name.
39     *
40     * @return this domain's name.
41     */
42    String   getDomainName();
43  
44    /**
45     * Insert a message in the <code>MessageQueue</code>.
46     * This method is used during initialisation to restore the component
47     * state from persistent storage.
48     *
49     * @param msg     the message
50     */
51    void insert(Message msg);
52  
53    /**
54     * Saves logical clock information to persistent storage.
55     */
56    void save() throws IOException  ;
57  
58    /**
59     * Restores logical clock information from persistent storage.
60     */
61    void restore() throws Exception  ;
62  
63    /**
64     *  Adds a message in "ready to deliver" list. This method allocates a
65     * new time stamp to the message ; be Careful, changing the stamp imply
66     * the filename change too.
67     */
68    void post(Message msg) throws Exception  ;
69  
70    /**
71     * Validates all messages pushed in queue during transaction session.
72     */
73    void validate();
74  
75    /**
76     * Causes this component to begin execution.
77     *
78     * @see stop
79     */
80    void start() throws Exception  ;
81  
82    /**
83     * Forces the component to stop executing.
84     *
85     * @see start
86     */
87    void stop();
88  
89    /**
90     * Deletes the component, removes all persistent datas. The component
91     * may have been previously stopped, and removed from MessageConsumer
92     * list.
93     * This operation use Transaction calls, you may use commit to validate it.
94     *
95     * @see fr.dyade.aaa.util.Transaction 
96     */
97    void delete() throws IllegalStateException  ;
98  
99    /**
100    *  Get this consumer's <code>MessageQueue</code>. Use in administration and
101    * debug tasks, should be replaced by a common attribute.
102    *
103    * @return this <code>MessageConsumer</code>'s queue.
104    */
105   MessageQueue getQueue();
106 
107   /**
108    *  Tests if the component is alive. A <code>MessageConsumer</code> is alive
109    * if it has been started and has not yet stopped.
110    *
111    * @return    true if this <code>MessageConsumer</code> is alive; false
112    *        otherwise.
113    */
114   boolean isRunning();
115 }
116
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