SchemaManager


1   /*
2    * Copyright 2002 (C) TJDO.
3    * All rights reserved.
4    *
5    * This software is distributed under the terms of the TJDO License version 1.0.
6    * See the terms of the TJDO License in the documentation provided with this software.
7    *
8    * $Id: SchemaManager.java,v 1.4 2003/10/18 22:05:16 jackknifebarber Exp $
9    */
10  
11  package com.triactive.jdo;
12  
13  
14  /**
15   * An interface to perform limited storage management on a database schema
16   * used by TJDO.
17   *
18   * @author <a HREF="mailto:mmartin5@austin.rr.com">Mike Martin</a>
19   * @version $Revision: 1.4 $
20   *
21   * @see SchemaManagerFactory
22   */
23  
24  public interface SchemaManager
25  {
26      /**
27       * Returns the name of the database schema.
28       *
29       * @return  The name of the database schema, or <code>null</code> if the
30       *          DBMS does not support the concept of schemas.
31       */
32      String   getSchemaName();
33  
34      /**
35       * Adds to the schema any database objects (tables, views, constraints,
36       * indexes, etc.) necessary to enable persistence of the given
37       * PersistenceCapable class(es).
38       * If any of the objects already exist, they are validated for structural
39       * correctness; that is, checked to ensure that they "match" the current
40       * class code and JDO metadata.
41       * <p>
42       * This method is primarily useful for applications that wish to perform all
43       * of their database initialization up front, rather than wait for the TJDO
44       * runtime to do it on-demand.
45       * <p>
46       * SQL identifiers for new database objects are chosen so as not to collide
47       * with any existing objects.
48       * Therefore it is always safe for TJDO and non-TJDO code to share the same
49       * database schema.
50       *
51       * @param classes   The class(es) to be added.
52       *
53       * @exception SchemaValidationException
54       *      If there is some mismatch between the current schema contents and
55       *      those necessary to enable persistence of the given classes.
56       */
57      void addClasses(Class  [] classes);
58  
59      /**
60       * Removes from the schema any existing database tables used in persisting
61       * the given PersistenceCapable class(es).
62       * <p>
63       * This method will fail if the relevant tables are depended upon by others
64       * used for classes that are not being removed.
65       * In case of failure, it is unspecified whether or not any tables were
66       * actually removed.
67       * <p>
68       * After dropping tables this method performs an implicit {@link #reset}.
69       *
70       * @param classes   The class(es) whose tables are to be removed.
71       */
72      void dropTablesFor(Class  [] classes);
73  
74      /**
75       * Drops all tables in the schema.
76       * This empties the schema of all database objects managed by TJDO.
77       * All objects not managed by TJDO are left untouched.
78       * <p>
79       * After dropping tables this method performs an implicit {@link #reset}.
80       */
81      void dropAllTables();
82  
83      /**
84       * Resets the schema manager back to its initial state.
85       * This method discards all knowledge of persistent classes and the state of
86       * the schema.
87       * After reset(), all initialization procedures such as schema validation
88       * etc. will be repeated as necessary as though the JVM were starting anew.
89       */
90      void reset();
91  }
92
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