MarshalledTupleKeyEntity


1   /*-
2    * See the file LICENSE for redistribution information.
3    *
4    * Copyright (c) 2000,2006 Oracle.  All rights reserved.
5    *
6    * $Id: MarshalledTupleKeyEntity.java,v 1.22 2006/10/30 21:14:08 bostic Exp $
7    */
8   
9   package com.sleepycat.bind.tuple;
10  
11  /**
12   * A marshalling interface implemented by entity classes that represent keys as
13   * tuples. Since <code>MarshalledTupleKeyEntity</code> objects are instantiated
14   * using Java deserialization, no particular constructor is required by classes
15   * that implement this interface.
16   *
17   * <p>Note that a marshalled tuple key extractor is somewhat less efficient
18   * than a non-marshalled key tuple extractor because more conversions are
19   * needed.  A marshalled key extractor must convert the entry to an object in
20   * order to extract the key fields, while an unmarshalled key extractor does
21   * not.</p>
22   *
23   * @author Mark Hayes
24   * @see TupleTupleMarshalledBinding
25   * @see com.sleepycat.bind.serial.TupleSerialMarshalledBinding
26   */
27  public interface MarshalledTupleKeyEntity {
28  
29      /**
30       * Extracts the entity's primary key and writes it to the key output.
31       *
32       * @param keyOutput is the output tuple.
33       */
34      void marshalPrimaryKey(TupleOutput keyOutput);
35  
36      /**
37       * Completes construction of the entity by setting its primary key from the
38       * stored primary key.
39       *
40       * @param keyInput is the input tuple.
41       */
42      void unmarshalPrimaryKey(TupleInput keyInput);
43  
44      /**
45       * Extracts the entity's secondary key and writes it to the key output.
46       *
47       * @param keyName identifies the secondary key.
48       *
49       * @param keyOutput is the output tuple.
50       *
51       * @return true if a key was created, or false to indicate that the key is
52       * not present.
53       */
54      boolean marshalSecondaryKey(String   keyName, TupleOutput keyOutput);
55  
56      /**
57       * Clears the entity's secondary key fields for the given key name.
58       *
59       * <p>The specified index key should be changed by this method such that
60       * {@link #marshalSecondaryKey} for the same key name will return false.
61       * Other fields in the data object should remain unchanged.</p>
62       *
63       * <!-- begin JE only -->
64       * <p>If {@link com.sleepycat.je.ForeignKeyDeleteAction#NULLIFY} was
65       * specified when opening the secondary database, this method is called
66       * when the entity for this foreign key is deleted.  If NULLIFY was not
67       * specified, this method will not be called and may always return
68       * false.</p>
69       * <!-- end JE only -->
70       *
71       * @param keyName identifies the secondary key.
72       *
73       * @return true if the key was cleared, or false to indicate that the key
74       * is not present and no change is necessary.
75       */
76      boolean nullifyForeignKey(String   keyName);
77  }
78
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