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1   /*
2    *   Copyright 2004 The Apache Software Foundation
3    *
4    *   Licensed under the Apache License, Version 2.0 (the "License");
5    *   you may not use this file except in compliance with the License.
6    *   You may obtain a copy of the License at
7    *
8    *       http://www.apache.org/licenses/LICENSE-2.0
9    *
10   *   Unless required by applicable law or agreed to in writing, software
11   *   distributed under the License is distributed on an "AS IS" BASIS,
12   *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   *   See the License for the specific language governing permissions and
14   *   limitations under the License.
15   *
16   */
17  package org.apache.ldap.server.invocation;
18  
19  
20  import java.io.Serializable;
21  import java.util.Stack;
22  
23  import javax.naming.NamingException;
24  
25  import org.apache.ldap.server.BackingStore;
26  
27  
28  /***
29   * Represents a method invocation on {@link BackingStore}s. You can perform any
30   * {@link BackingStore} calls by invoking {@link
31   * org.apache.ldap.server.jndi.JndiProvider#invoke(Invocation)}.<p/>
32   * This class is abstract, and developers should extend this class to
33   * represent the actual method invocations.
34   *
35   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
36   * @version $Rev: 159467 $, $Date: 2005-03-30 02:38:30 -0500 (Wed, 30 Mar 2005) $
37   */
38  public abstract class Invocation implements Serializable
39  {
40  
41      protected transient Object returnValue;
42  
43      protected transient Stack contextStack;
44  
45      
46      /***
47       * Creates a new instance.  This constructor does nothing.
48       */
49      protected Invocation()
50      {
51      }
52  
53  
54      /***
55       * Returns the returnValue object for this invocation.
56       */
57      public Object getReturnValue()
58      {
59          return returnValue;
60      }
61  
62  
63      /***
64       * Sets the returnValue object for this invocation.
65       */
66      public void setReturnValue( Object returnValue )
67      {
68          this.returnValue = returnValue;
69      }
70  
71  
72      /***
73       * Gets the context stack in which this invocation occurs.  The
74       * context stack is a stack of LdapContexts.
75       *
76       * @return a stack of LdapContexts in which the invocation occurs
77       */
78      public Stack getContextStack()
79      {
80          return contextStack;
81      }
82  
83  
84      /***
85       * Sets the context stack in which this invocation occurs.  The context stack
86       * is a stack of LdapContexts.
87       *
88       * @param contextStack a stack of LdapContexts in which the invocation occurs
89       */
90      public void setContextStack( Stack contextStack )
91      {
92          this.contextStack = contextStack;
93      }
94  
95  
96      /***
97       * Executes this invocation on the specified <code>store</code>. The default
98       * implementation calls an abstract method {@link #doExecute(BackingStore)}
99       * and sets the <code>returnValue</code> property of this invocation to its return value.
100      *
101      * @throws NamingException if the operation failed
102      */
103     public void execute( BackingStore store ) throws NamingException
104     {
105         setReturnValue( doExecute( store ) );
106     }
107 
108 
109     /***
110      * Implement this method to invoke the appropriate operation on the specified
111      * <code>store</code>.  Returned value will be set as the <code>returnValue</code> proeprty of this invocation.
112      *
113      * @throws NamingException if the operation failed
114      */
115     protected abstract Object doExecute( BackingStore store ) throws NamingException;
116 }