Java example source code file (SyncProvider.java)

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datasource_db_lock, datasource_no_lock, datasource_row_lock, grade_check_all_at_commit, grade_check_modified_at_commit, grade_lock_when_loaded, grade_none, nonupdatable_view_sync, rowsetreader, rowsetwriter, sql, string, syncprovider, syncproviderexception, updatable_view_sync

The SyncProvider.java Java example source code

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package javax.sql.rowset.spi;

import javax.sql.*;

/**
 * The synchronization mechanism that provides reader/writer capabilities for
 * disconnected <code>RowSet objects.
 * A <code>SyncProvider implementation is a class that extends the
 * <code>SyncProvider abstract class.
 * <P>
 * A <code>SyncProvider implementation is
 * identified by a unique ID, which is its fully qualified class name.
 * This name must be registered with the
 * <code>SyncFactory SPI, thus making the implementation available to
 * all <code>RowSet implementations.
 * The factory mechanism in the reference implementation uses this name to instantiate
 * the implementation, which can then provide a <code>RowSet object with its
 * reader (a <code>javax.sql.RowSetReader object) and its writer (a
 * <code>javax.sql.RowSetWriter object).
 * <P>
 * The Jdbc <code>RowSet Implementations specification provides two
 * reference implementations of the <code>SyncProvider abstract class:
 * <code>RIOptimisticProvider and RIXMLProvider.
 * The <code>RIOptimisticProvider can set any RowSet
 * implementation with a <code>RowSetReader object and a
 * <code>RowSetWriter object.  However, only the RIXMLProvider
 * implementation can set an <code>XmlReader object and an
 * <code>XmlWriter object. A WebRowSet object uses the
 * <code>XmlReader object to read data in XML format to populate itself with that
 * data.  It uses the <code>XmlWriter object to write itself to a stream or
 * <code>java.io.Writer object in XML format.
 *
 * <h3>1.0 Naming Convention for Implementations
 * As a guide  to naming <code>SyncProvider
 * implementations, the following should be noted:
 * <UL>
 * <li>The name for a SyncProvider implementation
 * is its fully qualified class name.
 * <li>It is recommended that vendors supply a
 * <code>SyncProvider implementation in a package named providers.
 * </UL>
 * <p>
 * For instance, if a vendor named Fred, Inc. offered a
 * <code>SyncProvider implementation, you could have the following:
 * <PRE>
 *     Vendor name:  Fred, Inc.
 *     Domain name of vendor:  com.fred
 *     Package name:  com.fred.providers
 *     SyncProvider implementation class name:  HighAvailabilityProvider
 *
 *     Fully qualified class name of SyncProvider implementation:
 *                        com.fred.providers.HighAvailabilityProvider
 * </PRE>
 * <P>
 * The following line of code uses the fully qualified name to register
 * this implementation with the <code>SyncFactory static instance.
 * <PRE>
 *     SyncFactory.registerProvider(
 *                          "com.fred.providers.HighAvailabilityProvider");
 * </PRE>
 * <P>
 * The default <code>SyncProvider object provided with the reference
 * implementation uses the following name:
 * <pre>
 *     com.sun.rowset.providers.RIOptimisticProvider
 * </pre>
 * <p>
 * A vendor can register a <code>SyncProvider implementation class name
 * with Oracle Corporation by sending email to jdbc@sun.com.
 * Oracle will maintain a database listing the
 * available <code>SyncProvider implementations for use with compliant
 * <code>RowSet implementations.  This database will be similar to the
 * one already maintained to list available JDBC drivers.
 * <P>
 * Vendors should refer to the reference implementation synchronization
 * providers for additional guidance on how to implement a new
 * <code>SyncProvider implementation.
 *
 * <h3>2.0 How a RowSet Object Gets Its Provider
 *
 * A disconnected <code>Rowset object may get access to a
 * <code>SyncProvider object in one of the following two ways:
 * <UL>
 *  <LI>Using a constructor

 *      <PRE>
 *       CachedRowSet crs = new CachedRowSet(
 *                  "com.fred.providers.HighAvailabilitySyncProvider");
 *      </PRE>
 *  <LI>Using the setSyncProvider method
 *      <PRE>
 *       CachedRowSet crs = new CachedRowSet();
 *       crs.setSyncProvider("com.fred.providers.HighAvailabilitySyncProvider");
 *      </PRE>

 * </UL>
 * <p>
 * By default, the reference implementations of the <code>RowSet synchronization
 * providers are always available to the Java platform.
 * If no other pluggable synchronization providers have been correctly
 * registered, the <code>SyncFactory will automatically generate
 * an instance of the default <code>SyncProvider reference implementation.
 * Thus, in the preceding code fragment, if no implementation named
 * <code>com.fred.providers.HighAvailabilitySyncProvider has been
 * registered with the <code>SyncFactory instance, crs will be
 * assigned the default provider in the reference implementation, which is
 * <code>com.sun.rowset.providers.RIOptimisticProvider.
 *
 * <h3>3.0 Violations and Synchronization Issues
 * If an update between a disconnected <code>RowSet object
 * and a data source violates
 * the original query or the underlying data source constraints, this will
 * result in undefined behavior for all disconnected <code>RowSet implementations
 * and their designated <code>SyncProvider implementations.
 * Not defining the behavior when such violations occur offers greater flexibility
 * for a <code>SyncProvider
 * implementation to determine its own best course of action.
 * <p>
 * A <code>SyncProvider implementation
 * may choose to implement a specific handler to
 * handle a subset of query violations.
 * However if an original query violation or a more general data source constraint
 * violation is not handled by the <code>SyncProvider implementation,
 * all <code>SyncProvider
 * objects must throw a <code>SyncProviderException.
 *
 * <h3>4.0 Updatable SQL VIEWs
 * It is possible for any disconnected or connected <code>RowSet object to be populated
 * from an SQL query that is formulated originally from an SQL <code>VIEW.
 * While in many cases it is possible for an update to be performed to an
 * underlying view, such an update requires additional metadata, which may vary.
 * The <code>SyncProvider class provides two constants to indicate whether
 * an implementation supports updating an SQL <code>VIEW.
 * <ul>
 * <li>NONUPDATABLE_VIEW_SYNC - Indicates that a SyncProvider
 * implementation does not support synchronization with an SQL <code>VIEW as the
 * underlying source of data for the <code>RowSet object.
 * <li>UPDATABLE_VIEW_SYNC - Indicates that a
 * <code>SyncProvider implementation
 * supports synchronization with an SQL <code>VIEW as the underlying source
 * of data.
 * </ul>
 * <P>
 * The default is for a <code>RowSet object not to be updatable if it was
 * populated with data from an SQL <code>VIEW.
 *
 * <h3>5.0 SyncProvider Constants
 * The <code>SyncProvider class provides three sets of constants that
 * are used as return values or parameters for <code>SyncProvider methods.
 * <code>SyncProvider objects may be implemented to perform synchronization
 * between a <code>RowSet object and its underlying data source with varying
 * degrees of of care. The first group of constants indicate how synchronization
 * is handled. For example, <code>GRADE_NONE indicates that a
 * <code>SyncProvider object will not take any care to see what data is
 * valid and will simply write the <code>RowSet data to the data source.
 * <code>GRADE_MODIFIED_AT_COMMIT indicates that the provider will check
 * only modified data for validity.  Other grades check all data for validity
 * or set locks when data is modified or loaded.
 * <OL>
 *  <LI>Constants to indicate the synchronization grade of a
 *     <code>SyncProvider object
 *   <UL>
 *    <LI>SyncProvider.GRADE_NONE
 *    <LI>SyncProvider.GRADE_MODIFIED_AT_COMMIT
 *    <LI>SyncProvider.GRADE_CHECK_ALL_AT_COMMIT
 *    <LI>SyncProvider.GRADE_LOCK_WHEN_MODIFIED
 *    <LI>SyncProvider.GRADE_LOCK_WHEN_LOADED
 *   </UL>
 *  <LI>Constants to indicate what locks are set on the data source
 *   <UL>
 *     <LI>SyncProvider.DATASOURCE_NO_LOCK
 *     <LI>SyncProvider.DATASOURCE_ROW_LOCK
 *     <LI>SyncProvider.DATASOURCE_TABLE_LOCK
 *     <LI>SyncProvider.DATASOURCE_DB_LOCK
 *   </UL>
 *  <LI>Constants to indicate whether a SyncProvider object can
 *       perform updates to an SQL <code>VIEW 

 *       These constants are explained in the preceding section (4.0).
 *   <UL>
 *     <LI>SyncProvider.UPDATABLE_VIEW_SYNC
 *     <LI>SyncProvider.NONUPDATABLE_VIEW_SYNC
 *   </UL>
 * </OL>
 *
 * @author Jonathan Bruce
 * @see javax.sql.rowset.spi.SyncFactory
 * @see javax.sql.rowset.spi.SyncFactoryException
 */
public abstract class SyncProvider {

   /**
    * Creates a default <code>SyncProvider object.
    */
    public SyncProvider() {
    }

    /**
     * Returns the unique identifier for this <code>SyncProvider object.
     *
     * @return a <code>String object with the fully qualified class name of
     *         this <code>SyncProvider object
     */
    public abstract String getProviderID();

    /**
     * Returns a <code>javax.sql.RowSetReader object, which can be used to
     * populate a <code>RowSet object with data.
     *
     * @return a <code>javax.sql.RowSetReader object
     */
    public abstract RowSetReader getRowSetReader();

    /**
     * Returns a <code>javax.sql.RowSetWriter object, which can be
     * used to write a <code>RowSet object's data back to the
     * underlying data source.
     *
     * @return a <code>javax.sql.RowSetWriter object
     */
    public abstract RowSetWriter getRowSetWriter();

    /**
     * Returns a constant indicating the
     * grade of synchronization a <code>RowSet object can expect from
     * this <code>SyncProvider object.
     *
     * @return an int that is one of the following constants:
     *           SyncProvider.GRADE_NONE,
     *           SyncProvider.GRADE_CHECK_MODIFIED_AT_COMMIT,
     *           SyncProvider.GRADE_CHECK_ALL_AT_COMMIT,
     *           SyncProvider.GRADE_LOCK_WHEN_MODIFIED,
     *           SyncProvider.GRADE_LOCK_WHEN_LOADED
     */
    public abstract int getProviderGrade();


    /**
     * Sets a lock on the underlying data source at the level indicated by
     * <i>datasource_lock. This should cause the
     * <code>SyncProvider to adjust its behavior by increasing or
     * decreasing the level of optimism it provides for a successful
     * synchronization.
     *
     * @param datasource_lock one of the following constants indicating the severity
     *           level of data source lock required:
     * <pre>
     *           SyncProvider.DATASOURCE_NO_LOCK,
     *           SyncProvider.DATASOURCE_ROW_LOCK,
     *           SyncProvider.DATASOURCE_TABLE_LOCK,
     *           SyncProvider.DATASOURCE_DB_LOCK,
     * </pre>
     * @throws SyncProviderException if an unsupported data source locking level
     *           is set.
     * @see #getDataSourceLock
     */
    public abstract void setDataSourceLock(int datasource_lock)
        throws SyncProviderException;

    /**
     * Returns the current data source lock severity level active in this
     * <code>SyncProvider implementation.
     *
     * @return a constant indicating the current level of data source lock
     *        active in this <code>SyncProvider object;
     *         one of the following:
     * <pre>
     *           SyncProvider.DATASOURCE_NO_LOCK,
     *           SyncProvider.DATASOURCE_ROW_LOCK,
     *           SyncProvider.DATASOURCE_TABLE_LOCK,
     *           SyncProvider.DATASOURCE_DB_LOCK
     * </pre>
     * @throws SyncProviderException if an error occurs determining the data
     *        source locking level.
     * @see #setDataSourceLock

     */
    public abstract int getDataSourceLock()
        throws SyncProviderException;

    /**
     * Returns whether this <code>SyncProvider implementation
     * can perform synchronization between a <code>RowSet object
     * and the SQL <code>VIEW in the data source from which
     * the <code>RowSet object got its data.
     *
     * @return an <code>int saying whether this SyncProvider
     *         object supports updating an SQL <code>VIEW; one of the
     *         following:
     *            SyncProvider.UPDATABLE_VIEW_SYNC,
     *            SyncProvider.NONUPDATABLE_VIEW_SYNC
     */
    public abstract int supportsUpdatableView();

    /**
     * Returns the release version of this <code>SyncProvider instance.
     *
     * @return a <code>String detailing the release version of the
     *     <code>SyncProvider implementation
     */
    public abstract String getVersion();

    /**
     * Returns the vendor name of this <code>SyncProvider instance
     *
     * @return a <code>String detailing the vendor name of this
     *     <code>SyncProvider implementation
     */
    public abstract String getVendor();

    /*
     * Standard description of synchronization grades that a SyncProvider
     * could provide.
     */

    /**
     * Indicates that no synchronization with the originating data source is
     * provided. A <code>SyncProvider
     * implementation returning this grade will simply attempt to write
     * updates in the <code>RowSet object to the underlying data
     * source without checking the validity of any data.
     *
     */
    public static final int GRADE_NONE = 1;

    /**
     * Indicates a low level optimistic synchronization grade with
     * respect to the originating data source.
     *
     * A <code>SyncProvider implementation
     * returning this grade will check only rows that have changed.
     *
     */
    public static final int GRADE_CHECK_MODIFIED_AT_COMMIT = 2;

    /**
     * Indicates a high level optimistic synchronization grade with
     * respect to the originating data source.
     *
     * A <code>SyncProvider implementation
     * returning this grade will check all rows, including rows that have not
     * changed.
     */
    public static final int GRADE_CHECK_ALL_AT_COMMIT = 3;

    /**
     * Indicates a pessimistic synchronization grade with
     * respect to the originating data source.
     *
     * A <code>SyncProvider
     * implementation returning this grade will lock the row in the originating
     * data source.
     */
    public static final int GRADE_LOCK_WHEN_MODIFIED = 4;

    /**
     * Indicates the most pessimistic synchronization grade with
     * respect to the originating
     * data source. A <code>SyncProvider
     * implementation returning this grade will lock the entire view and/or
     * table affected by the original statement used to populate a
     * <code>RowSet object.
     */
    public static final int GRADE_LOCK_WHEN_LOADED = 5;

    /**
     * Indicates that no locks remain on the originating data source. This is the default
     * lock setting for all <code>SyncProvider implementations unless
     * otherwise directed by a <code>RowSet object.
     */
    public static final int DATASOURCE_NO_LOCK = 1;

    /**
     * Indicates that a lock is placed on the rows that are touched by the original
     * SQL statement used to populate the <code>RowSet object
     * that is using this <code>SyncProvider object.
     */
    public static final int DATASOURCE_ROW_LOCK = 2;

    /**
     * Indicates that a lock is placed on all tables that are touched by the original
     * SQL statement used to populate the <code>RowSet object
     * that is using this <code>SyncProvider object.
     */
    public static final int DATASOURCE_TABLE_LOCK = 3;

    /**
     * Indicates that a lock is placed on the entire data source that is the source of
     * data for the <code>RowSet object
     * that is using this <code>SyncProvider object.
     */
    public static final int DATASOURCE_DB_LOCK = 4;

    /**
     * Indicates that a <code>SyncProvider implementation
     * supports synchronization between a <code>RowSet object and
     * the SQL <code>VIEW used to populate it.
     */
    public static final int UPDATABLE_VIEW_SYNC = 5;

    /**
     * Indicates that a <code>SyncProvider implementation
     * does <B>not support synchronization between a RowSet
     * object and the SQL <code>VIEW used to populate it.
     */
    public static final int NONUPDATABLE_VIEW_SYNC = 6;
}