ConsistencyAC


1   /*
2     Copyright (C) 2001-2002 Renaud Pawlak <renaud@aopsys.com>
3   
4     This program is free software; you can redistribute it and/or modify
5     it under the terms of the GNU Lesser General Public License as
6     published by the Free Software Foundation; either version 2 of the
7     License, or (at your option) any later version.
8   
9     This program is distributed in the hope that it will be useful,
10    but WITHOUT ANY WARRANTY; without even the implied warranty of
11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12    GNU Lesser General Public License for more details.
13  
14    You should have received a copy of the GNU Lesser Generaly Public License
15    along with this program; if not, write to the Free Software
16    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
17  
18  package org.objectweb.jac.aspects.distribution;
19  
20  import org.objectweb.jac.core.*;
21  import org.objectweb.jac.aspects.distribution.consistency.*;
22  
23  /**
24   * This aspect component provides some consistency protocols that can
25   * be settled on a set of replicas.
26   *
27   * @see ConsistencyConf
28   * @author Renaud Pawlak
29   */
30  
31  public class ConsistencyAC extends AspectComponent {
32  
33     /**
34      * Adds a strong-push consistency protocol on a set of replicas
35      * called <code>wrappeeName</code>.
36      *
37      * <p>The classical use of this consistency protocol is that any
38      * replica forwards all the writing calls to all the replicas
39      * located on the hosts defined by the consistency.
40      *
41      * <p>It is called "push" since the replica pushes the data to the
42      * other replicas. Despite this strategy is the most curently used,
43      * other strong or weak consistency strategies can be implemented by
44      * other consistency protocols.
45      *
46      * @param wrappeeName the name of the object to be consistent
47      * @param methods a pointcut expression that defines the methods
48      * that will be pushed to the other replicas (generally the state
49      * modifiers -- use the MODIFIERS keyword in your expression)
50      * @param hosts the location of the replicas as a pointcut
51      * expression */
52  
53     public void addStrongPushConsistency(String   wrappeeName,
54                                          String   methods,
55                                          String   hosts) {
56        pointcut(wrappeeName, ".*", methods,
57                 new StrongPushConsistencyWrapper(this,hosts),
58                 hosts, null);
59     }
60  
61     /**
62      * Adds a strong-pull consistency protocol on a set of replicas
63      * called <code>wrappeeName</code>.
64      *
65      * <p>On contrary to the push consistency, this protocol pulls the
66      * data from the other replicas. Indeed, each time a data is read
67      * and is not locally available, it is fetched from the known
68      * replicas.
69      *
70      * @param wrappeeName the name of the object to be consistent
71      * @param methods a pointcut expression that defines the methods
72      * that will be pulled from the other replicas (generally the state
73      * readers -- use the keyword ACCESSORS in your expression)
74      * @param hosts the location of the replicas as a pointcut
75      * expression */
76  
77     public void addStrongPullConsistency(String   wrappeeName,
78                                          String   methods,
79                                          String   hosts) {
80        pointcut(wrappeeName, ".*", methods,
81                 new StrongPullConsistencyWrapper(this,hosts),
82                 hosts, null);
83     }
84  
85  }
86
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