/* * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved. * 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 * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.sql.rowset.spi; import javax.sql.*; /** * The synchronization mechanism that provides reader/writer capabilities for * disconnected <code>RowSet</code> objects. * A <code>SyncProvider</code> implementation is a class that extends the * <code>SyncProvider</code> abstract class. * <P> * A <code>SyncProvider</code> implementation is * identified by a unique ID, which is its fully qualified class name. * This name must be registered with the * <code>SyncFactory</code> SPI, thus making the implementation available to * all <code>RowSet</code> implementations. * The factory mechanism in the reference implementation uses this name to instantiate * the implementation, which can then provide a <code>RowSet</code> object with its * reader (a <code>javax.sql.RowSetReader</code> object) and its writer (a * <code>javax.sql.RowSetWriter</code> object). * <P> * The Jdbc <code>RowSet</code> Implementations specification provides two * reference implementations of the <code>SyncProvider</code> abstract class: * <code>RIOptimisticProvider</code> and <code>RIXMLProvider</code>. * The <code>RIOptimisticProvider</code> can set any <code>RowSet</code> * implementation with a <code>RowSetReader</code> object and a * <code>RowSetWriter</code> object.  However, only the <code>RIXMLProvider</code> * implementation can set an <code>XmlReader</code> object and an * <code>XmlWriter</code> object. A <code>WebRowSet</code> object uses the * <code>XmlReader</code> object to read data in XML format to populate itself with that * data.  It uses the <code>XmlWriter</code> object to write itself to a stream or * <code>java.io.Writer</code> object in XML format. * <P> * <h3>1.0 Naming Convention for Implementations</h3> * As a guide  to naming <code>SyncProvider</code> * implementations, the following should be noted: * <UL> * <li>The name for a <code>SyncProvider</code> implementation * is its fully qualified class name. * <li>It is recommended that vendors supply a * <code>SyncProvider</code> implementation in a package named <code>providers</code>. * </UL> * <p> * For instance, if a vendor named Fred, Inc. offered a * <code>SyncProvider</code> 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</code> static instance. * <PRE> *     SyncFactory.registerProvider( *                          "com.fred.providers.HighAvailabilityProvider"); * </PRE> * <P> * The default <code>SyncProvider</code> 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</code> implementation class name * with Oracle Corporation by sending email to jdbc@sun.com. * Oracle will maintain a database listing the * available <code>SyncProvider</code> implementations for use with compliant * <code>RowSet</code> 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</code> implementation. * * <h3>2.0 How a <code>RowSet</code> Object Gets Its Provider</h3> * * A disconnected <code>Rowset</code> object may get access to a * <code>SyncProvider</code> object in one of the following two ways: * <UL> *  <LI>Using a constructor<BR> *      <PRE> *       CachedRowSet crs = new CachedRowSet( *                  "com.fred.providers.HighAvailabilitySyncProvider"); *      </PRE> *  <LI>Using the <code>setSyncProvider</code> method *      <PRE> *       CachedRowSet crs = new CachedRowSet(); *       crs.setSyncProvider("com.fred.providers.HighAvailabilitySyncProvider"); *      </PRE>  * </UL> * <p> * By default, the reference implementations of the <code>RowSet</code> synchronization * providers are always available to the Java platform. * If no other pluggable synchronization providers have been correctly * registered, the <code>SyncFactory</code> will automatically generate * an instance of the default <code>SyncProvider</code> reference implementation. * Thus, in the preceding code fragment, if no implementation named * <code>com.fred.providers.HighAvailabilitySyncProvider</code> has been * registered with the <code>SyncFactory</code> instance, <i>crs</i> will be * assigned the default provider in the reference implementation, which is * <code>com.sun.rowset.providers.RIOptimisticProvider</code>. * <p> * <h3>3.0 Violations and Synchronization Issues</h3> * If an update between a disconnected <code>RowSet</code> 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</code> implementations * and their designated <code>SyncProvider</code> implementations. * Not defining the behavior when such violations occur offers greater flexibility * for a <code>SyncProvider</code> * implementation to determine its own best course of action. * <p> * A <code>SyncProvider</code> 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</code> implementation, * all <code>SyncProvider</code> * objects must throw a <code>SyncProviderException</code>. * <p> * <h3>4.0 Updatable SQL VIEWs</h3> * It is possible for any disconnected or connected <code>RowSet</code> object to be populated * from an SQL query that is formulated originally from an SQL <code>VIEW</code>. * 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</code> class provides two constants to indicate whether * an implementation supports updating an SQL <code>VIEW</code>. * <ul> * <li><code><b>NONUPDATABLE_VIEW_SYNC</b></code> - Indicates that a <code>SyncProvider</code> * implementation does not support synchronization with an SQL <code>VIEW</code> as the * underlying source of data for the <code>RowSet</code> object. * <li><code><b>UPDATABLE_VIEW_SYNC</b></code> - Indicates that a * <code>SyncProvider</code> implementation * supports synchronization with an SQL <code>VIEW</code> as the underlying source * of data. * </ul> * <P> * The default is for a <code>RowSet</code> object not to be updatable if it was * populated with data from an SQL <code>VIEW</code>. * <P> * <h3>5.0 <code>SyncProvider</code> Constants</h3> * The <code>SyncProvider</code> class provides three sets of constants that * are used as return values or parameters for <code>SyncProvider</code> methods. * <code>SyncProvider</code> objects may be implemented to perform synchronization * between a <code>RowSet</code> 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</code> indicates that a * <code>SyncProvider</code> object will not take any care to see what data is * valid and will simply write the <code>RowSet</code> data to the data source. * <code>GRADE_MODIFIED_AT_COMMIT</code> 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</code> 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 <code>SyncProvider</code> object can *       perform updates to an SQL <code>VIEW</code> <BR> *       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</code> object.    */    public SyncProvider() {    }     /**     * Returns the unique identifier for this <code>SyncProvider</code> object.     *     * @return a <code>String</code> object with the fully qualified class name of     *         this <code>SyncProvider</code> object     */    public abstract String getProviderID();     /**     * Returns a <code>javax.sql.RowSetReader</code> object, which can be used to     * populate a <code>RowSet</code> object with data.     *     * @return a <code>javax.sql.RowSetReader</code> object     */    public abstract RowSetReader getRowSetReader();     /**     * Returns a <code>javax.sql.RowSetWriter</code> object, which can be     * used to write a <code>RowSet</code> object's data back to the     * underlying data source.     *     * @return a <code>javax.sql.RowSetWriter</code> object     */    public abstract RowSetWriter getRowSetWriter();     /**     * Returns a constant indicating the     * grade of synchronization a <code>RowSet</code> object can expect from     * this <code>SyncProvider</code> 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</i>. This should cause the     * <code>SyncProvider</code> 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</code> implementation.     *     * @return a constant indicating the current level of data source lock     *        active in this <code>SyncProvider</code> object;     *         one of the following:     * <pre>     *           SyncProvider.DATASOURCE_NO_LOCK,     *           SyncProvider.DATASOURCE_ROW_LOCK,     *           SyncProvider.DATASOURCE_TABLE_LOCK,     *           SyncProvider.DATASOURCE_DB_LOCK     * </pre>     * @throws SyncProviderExceptiom if an error occurs determining the data     *        source locking level.     * @see #setDataSourceLock      */    public abstract int getDataSourceLock()        throws SyncProviderException;     /**     * Returns whether this <code>SyncProvider</code> implementation     * can perform synchronization between a <code>RowSet</code> object     * and the SQL <code>VIEW</code> in the data source from which     * the <code>RowSet</code> object got its data.     *     * @return an <code>int</code> saying whether this <code>SyncProvider</code>     *         object supports updating an SQL <code>VIEW</code>; one of the     *         following:     *            SyncProvider.UPDATABLE_VIEW_SYNC,     *            SyncProvider.NONUPDATABLE_VIEW_SYNC     */    public abstract int supportsUpdatableView();     /**     * Returns the release version of this <code>SyncProvider</code> instance.     *     * @return a <code>String</code> detailing the release version of the     *     <code>SyncProvider</code> implementation     */    public abstract String getVersion();     /**     * Returns the vendor name of this <code>SyncProvider</code> instance     *     * @return a <code>String</code> detailing the vendor name of this     *     <code>SyncProvider</code> 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</code>     * implementation returning this grade will simply attempt to write     * updates in the <code>RowSet</code> 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</code> 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</code> 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</code>     * 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</code>     * implementation returning this grade will lock the entire view and/or     * table affected by the original statement used to populate a     * <code>RowSet</code> 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</code> implementations unless     * otherwise directed by a <code>RowSet</code> 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</code> object     * that is using this <code>SyncProvider</code> 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</code> object     * that is using this <code>SyncProvider</code> 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</code> object     * that is using this <code>SyncProvider</code> object.     */    public static final int DATASOURCE_DB_LOCK = 4;     /**     * Indicates that a <code>SyncProvider</code> implementation     * supports synchronization between a <code>RowSet</code> object and     * the SQL <code>VIEW</code> used to populate it.     */    public static final int UPDATABLE_VIEW_SYNC = 5;     /**     * Indicates that a <code>SyncProvider</code> implementation     * does <B>not</B> support synchronization between a <code>RowSet</code>     * object and the SQL <code>VIEW</code> used to populate it.     */    public static final int NONUPDATABLE_VIEW_SYNC = 6;}