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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
FilteredRowSet must implement. The FilteredRowSetImpl 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.

1.0 Background

There are occasions when a RowSet 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 RowSet implementations; however,
this is an impractical approach for lightweight components such as disconnected
RowSet
objects. The FilteredRowSet interface seeks to address this need
without supplying a heavyweight query language along with the processing that
such a query language would require.


A JDBC FilteredRowSet standard implementation implements the
RowSet interfaces and extends the
CachedRowSetTM class. The
CachedRowSet class provides a set of protected cursor manipulation
methods, which a FilteredRowSet implementation can override
to supply filtering support.

2.0 Predicate Sharing

If a FilteredRowSet implementation is shared using the
inherited createShared method in parent interfaces, the
Predicate should be shared without modification by all
FilteredRowSet instance clones.

3.0 Usage



By implementing a Predicate (see example in Predicate
class JavaDoc), a FilteredRowSet could then be used as described
below.




    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



In the example above, we initialize a Range object which
implements the Predicate interface. This object expresses
the following constraints: All rows outputted or modified from this
FilteredRowSet object must fall between the values 'Alpha' and
'Bravo' both values inclusive, in the column 'columnName'. If a filter is
applied to a FilteredRowSet object that contains no data that
falls within the range of the filter, no rows are returned.


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.



4.0 Updating a FilteredRowSet Object

The predicate set on a FilteredRowSet object
applies a criterion on all rows in a
RowSet object to manage a subset of rows in a RowSet
object. This criterion governs the subset of rows that are visible and also
defines which rows can be modified, deleted or inserted.


Therefore, the predicate set on a FilteredRowSet object must be
considered as bi-directional and the set criterion as the gating mechanism
for all views and updates to the FilteredRowSet object. Any attempt
to update the FilteredRowSet that violates the criterion will
result in a SQLException object being thrown.


The FilteredRowSet range criterion can be modified by applying
a new Predicate object to the FilteredRowSet
instance at any time. This is  possible if no additional references to the
FilteredRowSet object are detected. A new filter has has an
immediate effect on criterion enforcement within the
FilteredRowSet object, and all subsequent views and updates will be
subject to similar enforcement.



5.0 Behavior of Rows Outside the Filter

Rows that fall outside of the filter set on a FilteredRowSet
object cannot be modified until the filter is removed or a
new filter is applied.


Furthermore, only rows that fall within the bounds of a filter will be
synchronized with the data source.

Author:Jonathan Bruce
/**
 * 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.
 *
 * <h3>1.0 Background</h3>
 *
 * 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><sup><font size=-2>TM</font></sup> 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.
 *
 * <h3>2.0 Predicate Sharing</h3>
 *
 * 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.
 *
 * <h3>3.0 Usage</h3>
 * <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.
 * <P>
 * <code>
 * <pre>
 *     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>
 * </code>
 * 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.
 * <p>
 * <h3>4.0 Updating a <code>FilteredRowSet</code> Object</h3>
 * 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 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.
 * <p>
 * <h3>5.0 Behavior of Rows Outside the Filter</h3>
 * 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
 */

public interface FilteredRowSet extends WebRowSet {

   
Applies the given Predicate object to this
FilteredRowSet
object. The filter applies controls both to inbound and outbound views,
constraining which rows are visible and which
rows can be manipulated.


A new Predicate object may be set at any time. This has the
effect of changing constraints on the RowSet object's data.
In addition, modifying the filter at runtime presents issues whereby
multiple components may be operating on one FilteredRowSet object.
Application developers must take responsibility for managing multiple handles
to FilteredRowSet objects when their underling Predicate
objects change.

Params:
  • p – a Predicate object defining the filter for this
FilteredRowSet object. Setting a null value
will clear the predicate, allowing all rows to become visible.
Throws:
  • SQLException – if an error occurs when setting the
    Predicate object
/**
    * 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 FilteredRowSet object.

Returns:p the Predicate for this FilteredRowSet
object; null if no filter has been set.
/**
    * 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() ;
}