001 /*
002 * JBoss DNA (http://www.jboss.org/dna)
003 * See the COPYRIGHT.txt file distributed with this work for information
004 * regarding copyright ownership. Some portions may be licensed
005 * to Red Hat, Inc. under one or more contributor license agreements.
006 * See the AUTHORS.txt file in the distribution for a full listing of
007 * individual contributors.
008 *
009 * JBoss DNA is free software. Unless otherwise indicated, all code in JBoss DNA
010 * is licensed to you under the terms of the GNU Lesser General Public License as
011 * published by the Free Software Foundation; either version 2.1 of
012 * the License, or (at your option) any later version.
013 *
014 * JBoss DNA is distributed in the hope that it will be useful,
015 * but WITHOUT ANY WARRANTY; without even the implied warranty of
016 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
017 * Lesser General Public License for more details.
018 *
019 * You should have received a copy of the GNU Lesser General Public
020 * License along with this software; if not, write to the Free
021 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
022 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
023 */
024 package org.jboss.dna.repository.service;
025
026 import java.util.concurrent.TimeUnit;
027 import net.jcip.annotations.ThreadSafe;
028
029 /**
030 * Contract defining an administrative interface for controlling the running state of a service.
031 *
032 * @author Randall Hauch
033 */
034 @ThreadSafe
035 public interface ServiceAdministrator {
036
037 /**
038 * The available states.
039 *
040 * @author Randall Hauch
041 */
042 public static enum State {
043 STARTED,
044 PAUSED,
045 SHUTDOWN,
046 TERMINATED;
047 }
048
049 /**
050 * Return the current state of this system.
051 *
052 * @return the current state
053 */
054 public State getState();
055
056 /**
057 * Set the state of the system. This method does nothing if the desired state matches the current state.
058 *
059 * @param state the desired state
060 * @return this object for method chaining purposes
061 * @see #setState(String)
062 * @see #start()
063 * @see #pause()
064 * @see #shutdown()
065 */
066 public ServiceAdministrator setState( State state );
067
068 /**
069 * Set the state of the system. This method does nothing if the desired state matches the current state.
070 *
071 * @param state the desired state in string form
072 * @return this object for method chaining purposes
073 * @throws IllegalArgumentException if the specified state string is null or does not match one of the predefined
074 * {@link State predefined enumerated values}
075 * @see #setState(State)
076 * @see #start()
077 * @see #pause()
078 * @see #shutdown()
079 */
080 public ServiceAdministrator setState( String state );
081
082 /**
083 * Start monitoring and sequence the events. This method can be called multiple times, including after the system is
084 * {@link #pause() paused}. However, once the system is {@link #shutdown() shutdown}, it cannot be started or paused.
085 *
086 * @return this object for method chaining purposes
087 * @throws IllegalStateException if called when the system has been {@link #shutdown() shutdown}.
088 * @see #pause()
089 * @see #shutdown()
090 * @see #isStarted()
091 */
092 public ServiceAdministrator start();
093
094 /**
095 * Temporarily stop monitoring and sequencing events. This method can be called multiple times, including after the system is
096 * {@link #start() started}. However, once the system is {@link #shutdown() shutdown}, it cannot be started or paused.
097 *
098 * @return this object for method chaining purposes
099 * @throws IllegalStateException if called when the system has been {@link #shutdown() shutdown}.
100 * @see #start()
101 * @see #shutdown()
102 * @see #isPaused()
103 */
104 public ServiceAdministrator pause();
105
106 /**
107 * Permanently stop monitoring and sequencing events. This method can be called multiple times, but only the first call has an
108 * effect. Once the system has been shutdown, it may not be {@link #start() restarted} or {@link #pause() paused}.
109 *
110 * @return this object for method chaining purposes
111 * @see #start()
112 * @see #pause()
113 * @see #isShutdown()
114 */
115 public ServiceAdministrator shutdown();
116
117 /**
118 * Blocks until the shutdown has completed, or the timeout occurs, or the current thread is interrupted, whichever happens
119 * first.
120 *
121 * @param timeout the maximum time to wait
122 * @param unit the time unit of the timeout argument
123 * @return <tt>true</tt> if this service complete shut down and <tt>false</tt> if the timeout elapsed before it was shut
124 * down completely
125 * @throws InterruptedException if interrupted while waiting
126 */
127 boolean awaitTermination( long timeout, TimeUnit unit ) throws InterruptedException;
128
129 /**
130 * Return whether this system has been started and is currently running.
131 *
132 * @return true if started and currently running, or false otherwise
133 * @see #start()
134 * @see #pause()
135 * @see #isPaused()
136 * @see #isShutdown()
137 * @see #isTerminated()
138 */
139 public boolean isStarted();
140
141 /**
142 * Return whether this system is currently paused.
143 *
144 * @return true if currently paused, or false otherwise
145 * @see #pause()
146 * @see #start()
147 * @see #isStarted()
148 * @see #isShutdown()
149 * @see #isTerminated()
150 */
151 public boolean isPaused();
152
153 /**
154 * Return whether this system has been shut down.
155 *
156 * @return true if this service has been shut down, or false otherwise
157 * @see #shutdown()
158 * @see #isPaused()
159 * @see #isStarted()
160 * @see #isTerminated()
161 */
162 public boolean isShutdown();
163
164 /**
165 * Return whether this system has finished {@link #shutdown() shutting down}. Note that <code>isTerminated</code> is never
166 * <code>true</code> unless either {@link #shutdown()} was called first.
167 *
168 * @return true if the system has finished shutting down, or false otherwise
169 * @see #shutdown()
170 * @see #isPaused()
171 * @see #isStarted()
172 * @see #isShutdown()
173 */
174 public boolean isTerminated();
175
176 }