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Java > Open Source Codes > org > apache > avalon > framework > component > Component


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55 package org.apache.avalon.framework.component;
56
57 /**
58  * This interface identifies classes that can be used as <code>Components</code>
59  * by a <code>Composable</code>.
60  *
61  * <p>
62  * The contract surrounding the <code>Component</code> is that it is
63  * used, but not a user. When a class implements this interface, it
64  * is stating that other entities may use that class.
65  * </p>
66  *
67  * <p>
68  * A <code>Component</code> is the basic building block of the Avalon Framework.
69  * When a class implements this interface, it allows itself to be
70  * managed by a <code>ComponentManager</code> and used by an outside
71  * element called a <code>Composable</code>. The <code>Composable</code>
72  * must know what type of <code>Component</code> it is accessing, so
73  * it will re-cast the <code>Component</code> into the type it needs.
74  * </p>
75  *
76  * <p>
77  * In order for a <code>Component</code> to be useful you must either
78  * extend this interface, or implement this interface in conjunction
79  * with one that actually has methods. The new interface is the contract
80  * with the <code>Composable</code> that this is a particular type of
81  * component, and as such it can perform those functions on that type
82  * of component.
83  * </p>
84  *
85  * <p>
86  * For example, we want a component that performs a logging function
87  * so we extend the <code>Component</code> to be a <code>LoggingComponent</code>.
88  * </p>
89  *
90  * <pre>
91  * interface LoggingComponent
92  * extends Component
93  * {
94  * log(String message);
95  * }
96  * </pre>
97  *
98  * <p>
99  * Now all <code>Composable</code>s that want to use this type of component,
100  * will re-cast the <code>Component</code> into a <code>LoggingComponent</code>
101  * and the <code>Composable</code> will be able to use the <code>log</code>
102  * method.
103  * </p>
104  *
105  * <p>
106  * <span style="color: red">Deprecated: </span><i>
107  * Deprecated without replacement. Should only be used while migrating away
108  * from a system based on Composable/ComponentManager. A generic <code>java.lang.Object</code>
109  * can be used as a replacement.
110  * </i>
111  * </p>
112  *
113  * @author <a HREF="mailto:dev@avalon.apache.org">Avalon Development Team</a>
114  * @version CVS $Revision: 1.14 $ $Date: 2003/02/11 15:58:38 $
115  */

116 public interface Component
117 {
118 }
119
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