1//
2//  ========================================================================
3//  Copyright (c) 1995-2014 Mort Bay Consulting Pty. Ltd.
4//  ------------------------------------------------------------------------
5//  All rights reserved. This program and the accompanying materials
6//  are made available under the terms of the Eclipse Public License v1.0
7//  and Apache License v2.0 which accompanies this distribution.
8//
9//      The Eclipse Public License is available at
10//      http://www.eclipse.org/legal/epl-v10.html
11//
12//      The Apache License v2.0 is available at
13//      http://www.opensource.org/licenses/apache2.0.php
14//
15//  You may elect to redistribute this code under either of these licenses.
16//  ========================================================================
17//
18
19package org.eclipse.jetty.util.component;
20
21import java.util.EventListener;
22
23/* ------------------------------------------------------------ */
24/**
25 * The lifecycle interface for generic components.
26 * <br />
27 * Classes implementing this interface have a defined life cycle
28 * defined by the methods of this interface.
29 *
30 *
31 */
32public interface LifeCycle
33{
34    /* ------------------------------------------------------------ */
35    /**
36     * Starts the component.
37     * @throws Exception If the component fails to start
38     * @see #isStarted()
39     * @see #stop()
40     * @see #isFailed()
41     */
42    public void start()
43        throws Exception;
44
45    /* ------------------------------------------------------------ */
46    /**
47     * Stops the component.
48     * The component may wait for current activities to complete
49     * normally, but it can be interrupted.
50     * @exception Exception If the component fails to stop
51     * @see #isStopped()
52     * @see #start()
53     * @see #isFailed()
54     */
55    public void stop()
56        throws Exception;
57
58    /* ------------------------------------------------------------ */
59    /**
60     * @return true if the component is starting or has been started.
61     */
62    public boolean isRunning();
63
64    /* ------------------------------------------------------------ */
65    /**
66     * @return true if the component has been started.
67     * @see #start()
68     * @see #isStarting()
69     */
70    public boolean isStarted();
71
72    /* ------------------------------------------------------------ */
73    /**
74     * @return true if the component is starting.
75     * @see #isStarted()
76     */
77    public boolean isStarting();
78
79    /* ------------------------------------------------------------ */
80    /**
81     * @return true if the component is stopping.
82     * @see #isStopped()
83     */
84    public boolean isStopping();
85
86    /* ------------------------------------------------------------ */
87    /**
88     * @return true if the component has been stopped.
89     * @see #stop()
90     * @see #isStopping()
91     */
92    public boolean isStopped();
93
94    /* ------------------------------------------------------------ */
95    /**
96     * @return true if the component has failed to start or has failed to stop.
97     */
98    public boolean isFailed();
99
100    /* ------------------------------------------------------------ */
101    public void addLifeCycleListener(LifeCycle.Listener listener);
102
103    /* ------------------------------------------------------------ */
104    public void removeLifeCycleListener(LifeCycle.Listener listener);
105
106
107    /* ------------------------------------------------------------ */
108    /** Listener.
109     * A listener for Lifecycle events.
110     */
111    public interface Listener extends EventListener
112    {
113        public void lifeCycleStarting(LifeCycle event);
114        public void lifeCycleStarted(LifeCycle event);
115        public void lifeCycleFailure(LifeCycle event,Throwable cause);
116        public void lifeCycleStopping(LifeCycle event);
117        public void lifeCycleStopped(LifeCycle event);
118    }
119}
120