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package javax.sql.rowset;

import java.sql.*;

import javax.sql.*;

import javax.naming.*;

import java.io.*;

import java.math.*;

/**

 * The standard interface that all standard implementations of

 * <code>FilteredRowSet</code> must implement. The <code>FilteredRowSetImpl</code> class

 * provides the reference implementation which may be extended if required.

 * Alternatively, a vendor is free to implement its own version

 * by implementing this interface.

 *

 * <h2>1.0 Background</h2>

 *

 * There are occasions when a <code>RowSet</code> object has a need to provide a degree

 * of filtering to its contents. One possible solution is to provide

 * a query language for all standard <code>RowSet</code> implementations; however,

 * this is an impractical approach for lightweight components such as disconnected

 * <code>RowSet</code>

 * objects. The <code>FilteredRowSet</code> interface seeks to address this need

 * without supplying a heavyweight query language along with the processing that

 * such a query language would require.

 * <p>

 * A JDBC <code>FilteredRowSet</code> standard implementation implements the

 * <code>RowSet</code> interfaces and extends the

 * <code>CachedRowSet</code> class. The

 * <code>CachedRowSet</code> class provides a set of protected cursor manipulation

 * methods, which a <code>FilteredRowSet</code> implementation can override

 * to supply filtering support.

 *

 * <h2>2.0 Predicate Sharing</h2>

 *

 * If a <code>FilteredRowSet</code> implementation is shared using the

 * inherited <code>createShared</code> method in parent interfaces, the

 * <code>Predicate</code> should be shared without modification by all

 * <code>FilteredRowSet</code> instance clones.

 *

 * <h2>3.0 Usage</h2>

 * <p>

 * By implementing a <code>Predicate</code> (see example in <a href="Predicate.html">Predicate</a>

 * class JavaDoc), a <code>FilteredRowSet</code> could then be used as described

 * below.

 *

 * <pre>

 * {@code

 *     FilteredRowSet frs = new FilteredRowSetImpl();

 *     frs.populate(rs);

 *

 *     Range name = new Range("Alpha", "Bravo", "columnName");

 *     frs.setFilter(name);

 *

 *     frs.next() // only names from "Alpha" to "Bravo" will be returned

 * }

 * </pre>

 * In the example above, we initialize a <code>Range</code> object which

 * implements the <code>Predicate</code> interface. This object expresses

 * the following constraints: All rows outputted or modified from this

 * <code>FilteredRowSet</code> object must fall between the values 'Alpha' and

 * 'Bravo' both values inclusive, in the column 'columnName'. If a filter is

 * applied to a <code>FilteredRowSet</code> object that contains no data that

 * falls within the range of the filter, no rows are returned.

 * <p>

 * This framework allows multiple classes implementing predicates to be

 * used in combination to achieved the required filtering result with

 * out the need for query language processing.

 *

 * <h2>4.0 Updating a <code>FilteredRowSet</code> Object</h2>

 * The predicate set on a <code>FilteredRowSet</code> object

 * applies a criterion on all rows in a

 * <code>RowSet</code> object to manage a subset of rows in a <code>RowSet</code>

 * object. This criterion governs the subset of rows that are visible and also

 * defines which rows can be modified, deleted or inserted.

 * <p>

 * Therefore, the predicate set on a <code>FilteredRowSet</code> object must be

 * considered as bi-directional and the set criterion as the gating mechanism

 * for all views and updates to the <code>FilteredRowSet</code> object. Any attempt

 * to update the <code>FilteredRowSet</code> that violates the criterion will

 * result in a <code>SQLException</code> object being thrown.

 * <p>

 * The <code>FilteredRowSet</code> range criterion can be modified by applying

 * a new <code>Predicate</code> object to the <code>FilteredRowSet</code>

 * instance at any time. This is  possible if no additional references to the

 * <code>FilteredRowSet</code> object are detected. A new filter has an

 * immediate effect on criterion enforcement within the

 * <code>FilteredRowSet</code> object, and all subsequent views and updates will be

 * subject to similar enforcement.

 *

 * <h2>5.0 Behavior of Rows Outside the Filter</h2>

 * Rows that fall outside of the filter set on a <code>FilteredRowSet</code>

 * object cannot be modified until the filter is removed or a

 * new filter is applied.

 * <p>

 * Furthermore, only rows that fall within the bounds of a filter will be

 * synchronized with the data source.

 *

 * @author Jonathan Bruce

 * @since 1.5

 */

public interface FilteredRowSet extends WebRowSet {

   /**

    * Applies the given <code>Predicate</code> object to this

    * <code>FilteredRowSet</code>

    * object. The filter applies controls both to inbound and outbound views,

    * constraining which rows are visible and which

    * rows can be manipulated.

    * <p>

    * A new <code>Predicate</code> object may be set at any time. This has the

    * effect of changing constraints on the <code>RowSet</code> object's data.

    * In addition, modifying the filter at runtime presents issues whereby

    * multiple components may be operating on one <code>FilteredRowSet</code> object.

    * Application developers must take responsibility for managing multiple handles

    * to <code>FilteredRowSet</code> objects when their underling <code>Predicate</code>

    * objects change.

    *

    * @param p a <code>Predicate</code> object defining the filter for this

    * <code>FilteredRowSet</code> object. Setting a <b>null</b> value

    * will clear the predicate, allowing all rows to become visible.

    *

    * @throws SQLException if an error occurs when setting the

    *     <code>Predicate</code> object

    */

    public void setFilter(Predicate p) throws SQLException;

   /**

    * Retrieves the active filter for this <code>FilteredRowSet</code> object.

    *

    * @return p the <code>Predicate</code> for this <code>FilteredRowSet</code>

    * object; <code>null</code> if no filter has been set.

    */

    public Predicate getFilter() ;

}