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1   /***
2    * Redistribution and use of this software and associated documentation
3    * ("Software"), with or without modification, are permitted provided
4    * that the following conditions are met:
5    *
6    * 1. Redistributions of source code must retain copyright
7    *    statements and notices.  Redistributions must also contain a
8    *    copy of this document.
9    *
10   * 2. Redistributions in binary form must reproduce the
11   *    above copyright notice, this list of conditions and the
12   *    following disclaimer in the documentation and/or other
13   *    materials provided with the distribution.
14   *
15   * 3. The name "Exolab" must not be used to endorse or promote
16   *    products derived from this Software without prior written
17   *    permission of Exoffice Technologies.  For written permission,
18   *    please contact info@exolab.org.
19   *
20   * 4. Products derived from this Software may not be called "Exolab"
21   *    nor may "Exolab" appear in their names without prior written
22   *    permission of Exoffice Technologies. Exolab is a registered
23   *    trademark of Exoffice Technologies.
24   *
25   * 5. Due credit should be given to the Exolab Project
26   *    (http://www.exolab.org/).
27   *
28   * THIS SOFTWARE IS PROVIDED BY EXOFFICE TECHNOLOGIES AND CONTRIBUTORS
29   * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
30   * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
31   * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
32   * EXOFFICE TECHNOLOGIES OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
33   * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
34   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
35   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
37   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
38   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
39   * OF THE POSSIBILITY OF SUCH DAMAGE.
40   *
41   * Copyright 1999-2004 (C) Exoffice Technologies Inc. All Rights Reserved.
42   *
43   * $Id: Service.java,v 1.2 2005/08/30 04:56:14 tanderson Exp $
44   */
45  package org.exolab.jms.service;
46  
47  
48  /***
49   * <code>Service</code> is an implementation of the {@link Serviceable}
50   * interface that provides default implementations for the {@link #start} and
51   * {@link #stop} methods.
52   *
53   * @version     $Revision: 1.2 $ $Date: 2005/08/30 04:56:14 $
54   * @author      <a href="mailto:jima@comware.com.au">Jim Alateras</a>
55   * @see         Serviceable
56   */
57  public abstract class Service implements Serviceable {
58  
59      /***
60       * The name of the service. May be <code>null</code>.
61       */
62      private final String _name;
63  
64      /***
65       * Determines if the service is started.
66       */
67      private volatile boolean _started = false;
68  
69  
70      /***
71       * Construct a new <code>Service</code>, with no name.
72       */
73      public Service() {
74          this(null);
75      }
76  
77      /***
78       * Construct a new <code>Service</code>, specifying its name.
79       * 
80       * @param name the name of the service. May be <code>null</code>
81       */
82      protected Service(String name) {
83          _name = name;
84      }
85  
86      /***
87       * Start the service.
88       *
89       * @throws ServiceException if the service fails to start, or is already
90       * started
91       */
92      public void start() throws ServiceException {
93          if (_started) {
94              throw new ServiceException("Service already started");
95          }
96  
97          doStart();
98  
99          _started = true;
100     }
101 
102     /***
103      * Stop the service.
104      *
105      * @throws ServiceException if the service fails to stop, or is already
106      * stopped
107      */
108     public void stop() throws ServiceException {
109         if (!_started) {
110             throw new ServiceException("Service not started");
111         }
112         doStop();
113 
114         _started = false;
115     }
116 
117     /***
118      * Convenience method for restarting the service. This operation can
119      * be called regardless the current state of the service.
120      *
121      * @throws ServiceException if the service fails to restart
122      */
123     public void restart() throws ServiceException {
124         if (_started) {
125             stop();
126         }
127         start();
128     }
129 
130     /***
131      * Determines if this service is started.
132      *
133      * @return <code>true</code> if the service is started;
134      * otherwise <code>false</code>
135      */
136     public boolean isStarted() {
137         return _started;
138     }
139 
140     /***
141      * Return the name of the service.
142      *
143      * @return the service name, or <code>null</code> if none was set.
144      */
145     public String getName() {
146         return _name;
147     }
148 
149     /***
150      * Return the state of the object as a string.
151      *
152      * @return a string form of the object state
153      */
154     public String toString() {
155         StringBuffer buf = new StringBuffer("Service:[");
156         buf.append("name=");
157         buf.append(_name);
158         buf.append("started=");
159         buf.append(_started);
160         buf.append("]");
161         return buf.toString();
162     }
163 
164     /***
165      * Start the service.
166      *
167      * @throws ServiceException if the service fails to start
168      */
169     protected void doStart() throws ServiceException {
170     }
171 
172     /***
173      * Stop the service.
174      *
175      * @throws ServiceException if the service fails to stop
176      */
177     protected void doStop() throws ServiceException {
178     }
179 
180 }