/*
* @(#)FilteredRowSet.java 1.7 04/05/29
*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
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.
*
* <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 <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() ;
}
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