BlobStoreInterface


1   /**
2    * com.mckoi.database.BlobStoreInterface  21 Jan 2003
3    *
4    * Mckoi SQL Database ( http://www.mckoi.com/database )
5    * Copyright (C) 2000, 2001, 2002  Diehl and Associates, Inc.
6    *
7    * This program is free software; you can redistribute it and/or
8    * modify it under the terms of the GNU General Public License
9    * Version 2 as published by the Free Software Foundation.
10   *
11   * This program is distributed in the hope that it will be useful,
12   * but WITHOUT ANY WARRANTY; without even the implied warranty of
13   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14   * GNU General Public License Version 2 for more details.
15   *
16   * You should have received a copy of the GNU General Public License
17   * Version 2 along with this program; if not, write to the Free Software
18   * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
19   *
20   * Change Log:
21   * 
22   * 
23   */
24  
25  package com.mckoi.database;
26  
27  import java.io.IOException  ;
28  import com.mckoi.database.global.Ref;
29  
30  /**
31   * A very restricted interface for accessing a blob store.  This is used by a
32   * MasterTableDataSource implementation to query and resolve blob information.
33   *
34   * @author Tobias Downer
35   */
36  
37  public interface BlobStoreInterface {
38  
39    /**
40     * Given a large object reference identifier, generates a Ref implementation
41     * that provides access to the information in the large object.  The Ref
42     * implementation returned by this object is a read-only static object.
43     * This may return either a BlobRef or a ClobRef object depending on the
44     * type of the object.
45     */
46    Ref getLargeObject(long reference_id) throws IOException  ;
47  
48    /**
49     * Tells the BlobStore that a static reference has been established in a
50     * table to the blob referenced by the given id.  This is used to count
51     * references to a blob, and possibly clean up a blob if there are no
52     * references remaining to it.
53     */
54    void establishReference(long reference_id);
55    
56    /**
57     * Tells the BlobStore that a static reference has been released to the
58     * given blob.  This would typically be called when the row in the database
59     * is removed.
60     */
61    void releaseReference(long reference_id);
62    
63  }
64  
65
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