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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.

 *

 * <h2>1.0 Naming Convention for Implementations</h2>

 * 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>

 * Vendors should refer to the reference implementation synchronization

 * providers for additional guidance on how to implement a new

 * <code>SyncProvider</code> implementation.

 *

 * <h2>2.0 How a <code>RowSet</code> Object Gets Its Provider</h2>

 *

 * 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>.

 *

 * <h2>3.0 Violations and Synchronization Issues</h2>

 * 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>.

 *

 * <h2>4.0 Updatable SQL VIEWs</h2>

 * 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>.

 *

 * <h2>5.0 <code>SyncProvider</code> Constants</h2>

 * 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 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

 * @since 1.5

 */

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 SyncProviderException 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;

}