PropertySetCallback


1   /*
2   
3      Derby - Class org.apache.derby.iapi.services.property.PropertySetCallback
4   
5      Licensed to the Apache Software Foundation (ASF) under one or more
6      contributor license agreements.  See the NOTICE file distributed with
7      this work for additional information regarding copyright ownership.
8      The ASF licenses this file to you under the Apache License, Version 2.0
9      (the "License"); you may not use this file except in compliance with
10     the License.  You may obtain a copy of the License at
11  
12        http://www.apache.org/licenses/LICENSE-2.0
13  
14     Unless required by applicable law or agreed to in writing, software
15     distributed under the License is distributed on an "AS IS" BASIS,
16     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17     See the License for the specific language governing permissions and
18     limitations under the License.
19  
20   */
21  
22  package org.apache.derby.iapi.services.property;
23  
24  import org.apache.derby.iapi.error.StandardException;
25  import org.apache.derby.iapi.services.daemon.Serviceable;
26  import java.io.Serializable  ;
27  import java.util.Dictionary  ;
28  
29  public interface PropertySetCallback {
30  
31      /**
32          Initialize the properties for this callback.
33          Called when addPropertySetNotification() is called
34          with a non-null transaction controller.
35          This allows code to set read its initial property
36          values at boot time.
37  
38          <P>
39          Code within an init() method should use the 3 argument
40          PropertyUtil method getPropertyFromSet() to obtain a property's value.
41  
42          @param dbOnly true if only per-database properties are to be looked at
43          @param p the complete set of per-database properties.
44      */ 
45      void init(boolean dbOnly, Dictionary   p);
46  
47      /**
48        Validate a property change.
49        @param key Property key for the property being set
50        @param value proposed new value for the property being set or null if
51               the property is being dropped.
52        @param p Property set before the change. SettingProperty may read but
53               must never change p.
54  
55        @return true if this object was interested in this property, false otherwise.
56        @exception StandardException Oh well.
57      */
58      boolean validate(String   key, Serializable   value, Dictionary   p)
59           throws StandardException;
60      /**
61        Apply a property change. Will only be called after validate has been called
62        and only if validate returned true. If this method is called then the
63        new value is the value to be used, ie. the property is not set in the
64        overriding JVM system set.
65  
66        @param key Property key for the property being set
67        @param value proposed new value for the property being set or null if
68               the property is being dropped.
69        @param p Property set before the change. SettingProperty may read but
70               must never change p.
71        @return post commit work for the property change.
72        @exception StandardException Oh well.
73      */
74      Serviceable apply(String   key, Serializable   value, Dictionary   p)
75           throws StandardException;
76      
77      /**
78  
79        Map a proposed new value for a property to an official value.
80  
81        Will only be called after apply() has been called.
82        @param key Property key for the property being set
83        @param value proposed new value for the property being set or null if
84               the property is being dropped.
85        @param p Property set before the change. SettingProperty may read but
86               must never change p.
87        @return new value for the change
88        @exception StandardException Oh well.
89      */
90      Serializable   map(String   key, Serializable   value, Dictionary   p)
91           throws StandardException;
92  }
93
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