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Java > Open Source Codes > org > apache > avalon > excalibur > source > SourceValidity


1 /*
2  * Copyright (C) The Apache Software Foundation. All rights reserved.
3  *
4  * This software is published under the terms of the Apache Software License
5  * version 1.1, a copy of which has been included with this distribution in
6  * the LICENSE.txt file.
7  */
8 package org.apache.avalon.excalibur.source;
9
10 /**
11  * A Validity object contains all information to check if a Source object is
12  * still valid.
13  * There are two possibilities: The validity object has all information
14  * to check by itself how long it is valid (e.g. given an expires date).
15  * The other possibility needs another (newer) validity object to compare
16  * against (e.g. to test a last modification date).
17  * To avoid testing, what the actual implementation of the validity object
18  * supports, the invocation order is to first call isValid() and only if
19  * this results in <code>false</code>, then to call isValid(SourceValidity).
20  * But remember to call the second isValid(SourceValidity) when <code>false</code>
21  * is returned by the first invocation!
22  *
23  * @author <a HREF="mailto:cziegeler@apache.org">Carsten Ziegeler</a>
24  * @version CVS $Revision: 1.3 $ $Date: 2002/01/08 13:43:48 $
25  */
26 public interface SourceValidity
27 extends java.io.Serializable JavaDoc {
28
29     /**
30      * Check if the component is still valid.
31      * If <code>false</code> is returned the isValid(SourceValidity) must be
32      * called afterwards!
33      */
34     boolean isValid();
35
36     /**
37      * Check if the component is still valid.
38      * This is only true, if the incoming Validity is of the same
39      * type and has the same values.
40      * The invocation order is that the isValid method of the
41      * old Validity object is called with the new one as a parameter
42      */
43     boolean isValid(SourceValidity newValidity);
44 }
45
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