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Java > Open Source Codes > org > osgi > framework > BundleActivator


1 /*
2  * $Header: /cvshome/build/org.osgi.framework/src/org/osgi/framework/BundleActivator.java,v 1.14 2007/02/21 16:49:05 hargrave Exp $
3  *
4  * Copyright (c) OSGi Alliance (2000, 2007). All Rights Reserved.
5  *
6  * Licensed under the Apache License, Version 2.0 (the "License");
7  * you may not use this file except in compliance with the License.
8  * You may obtain a copy of the License at
9  *
10  * http://www.apache.org/licenses/LICENSE-2.0
11  *
12  * Unless required by applicable law or agreed to in writing, software
13  * distributed under the License is distributed on an "AS IS" BASIS,
14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15  * See the License for the specific language governing permissions and
16  * limitations under the License.
17  */
18
19 package org.osgi.framework;
20
21 /**
22  * Customizes the starting and stopping of a bundle.
23  * <p>
24  * <code>BundleActivator</code> is an interface that may be implemented when a
25  * bundle is started or stopped. The Framework can create instances of a
26  * bundle's <code>BundleActivator</code> as required. If an instance's
27  * <code>BundleActivator.start</code> method executes successfully, it is
28  * guaranteed that the same instance's <code>BundleActivator.stop</code>
29  * method will be called when the bundle is to be stopped. The Framework must
30  * not concurrently call a <code>BundleActivator</code> object.
31  *
32  * <p>
33  * <code>BundleActivator</code> is specified through the
34  * <code>Bundle-Activator</code> Manifest header. A bundle can only specify a
35  * single <code>BundleActivator</code> in the Manifest file. Fragment bundles
36  * must not have a <code>BundleActivator</code>. The form of the Manifest
37  * header is:
38  *
39  * <p>
40  * <code>Bundle-Activator: <i>class-name</i></code>
41  *
42  * <p>
43  * where <code><i>class-name</i></code> is a fully qualified Java classname.
44  * <p>
45  * The specified <code>BundleActivator</code> class must have a public
46  * constructor that takes no parameters so that a <code>BundleActivator</code>
47  * object can be created by <code>Class.newInstance()</code>.
48  *
49  * @NotThreadSafe
50  * @version $Revision: 1.14 $
51  */
52
53 public interface BundleActivator {
54     /**
55      * Called when this bundle is started so the Framework can perform the
56      * bundle-specific activities necessary to start this bundle. This method
57      * can be used to register services or to allocate any resources that this
58      * bundle needs.
59      *
60      * <p>
61      * This method must complete and return to its caller in a timely manner.
62      *
63      * @param context The execution context of the bundle being started.
64      * @throws java.lang.Exception If this method throws an exception, this
65      * bundle is marked as stopped and the Framework will remove this
66      * bundle's listeners, unregister all services registered by this
67      * bundle, and release all services used by this bundle.
68      */
69     public void start(BundleContext context) throws Exception JavaDoc;
70
71     /**
72      * Called when this bundle is stopped so the Framework can perform the
73      * bundle-specific activities necessary to stop the bundle. In general, this
74      * method should undo the work that the <code>BundleActivator.start</code>
75      * method started. There should be no active threads that were started by
76      * this bundle when this bundle returns. A stopped bundle must not call any
77      * Framework objects.
78      *
79      * <p>
80      * This method must complete and return to its caller in a timely manner.
81      *
82      * @param context The execution context of the bundle being stopped.
83      * @throws java.lang.Exception If this method throws an exception, the
84      * bundle is still marked as stopped, and the Framework will remove
85      * the bundle's listeners, unregister all services registered by the
86      * bundle, and release all services used by the bundle.
87      */
88     public void stop(BundleContext context) throws Exception JavaDoc;
89 }
90
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