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Java > Open Source Codes > com > sun > enterprise > util > UniqueValueGenerator


1 /*
2  * The contents of this file are subject to the terms
3  * of the Common Development and Distribution License
4  * (the License). You may not use this file except in
5  * compliance with the License.
6  *
7  * You can obtain a copy of the license at
8  * https://glassfish.dev.java.net/public/CDDLv1.0.html or
9  * glassfish/bootstrap/legal/CDDLv1.0.txt.
10  * See the License for the specific language governing
11  * permissions and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL
14  * Header Notice in each file and include the License file
15  * at glassfish/bootstrap/legal/CDDLv1.0.txt.
16  * If applicable, add the following below the CDDL Header,
17  * with the fields enclosed by brackets [] replaced by
18  * you own identifying information:
19  * "Portions Copyrighted [year] [name of copyright owner]"
20  *
21  * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
22  */
23
24 package com.sun.enterprise.util;
25
26 /**
27  * A unique value generator is used to generate numbers
28  * that are guaranteed to be unique within a particular
29  * scope and lifetime of a J2EE server. See below for details.
30  * Generators support concurrent access. Each generator
31  * generates unique numbers within a particular context.
32  * Clients that need to draw numbers from the same "bucket"
33  * must use the same context.
34  *
35  * @author Kenneth Saks
36  */
37 public interface UniqueValueGenerator {
38
39     /**
40      * Generate a number that is guaranteed to be unique
41      * within the lifetime of one J2EE server instance
42      * on one machine.(in both single-vm and multi-vm modes)
43      * That is, between "j2ee -start" and "j2ee -stop".
44      * @exception UniqueValueGeneratorException if error occurs
45      */
46     long nextNumber() throws UniqueValueGeneratorException;
47
48     /**
49      * Generate an id that is guaranteed to be unique across
50      * multiple sessions of the same j2ee server on the same machine.
51      * @exception UniqueValueGeneratorException if error occurs
52      */
53     String JavaDoc nextId() throws UniqueValueGeneratorException;
54
55     /**
56      * Get the context within which unique numbers will be generated.
57      */
58     String JavaDoc getContext() throws UniqueValueGeneratorException;
59
60 }
61
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