/*
* JasperReports - Free Java Reporting Library.
* Copyright (C) 2001 - 2009 Jaspersoft Corporation. All rights reserved.
* http://www.jaspersoft.com
*
* Unless you have purchased a commercial license agreement from Jaspersoft,
* the following license terms apply:
*
* This program is part of JasperReports.
*
* JasperReports is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* JasperReports 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with JasperReports. If not, see <http://www.gnu.org/licenses/>.
*/
package net.sf.jasperreports.engine.query;
import net.sf.jasperreports.engine.JRDataSource;
import net.sf.jasperreports.engine.JRException;
/**
* Query executer interface.
* <p/>
* An implementation of this interface is created when the input data of a report/dataset
* is specified by a query.
* <p/>
* The implementation will run the query and create a {@link net.sf.jasperreports.engine.JRDataSource JRDataSource}
* from the result.
* <p/>
* The query executers would usually be initialized by a {@link net.sf.jasperreports.engine.query.JRQueryExecuterFactory JRQueryExecuterFactory}
* with the query and the parameter values.
*
* @author Lucian Chirita (lucianc@users.sourceforge.net)
* @version $Id: JRQueryExecuter.java 3034 2009-08-27 11:58:04Z teodord $
* @see net.sf.jasperreports.engine.query.JRQueryExecuterFactory
*/
public interface JRQueryExecuter
{
/**
* Executes the query and creates a {@link JRDataSource JRDataSource} out of the result.
*
* @return a {@link JRDataSource JRDataSource} wrapping the query execution result.
* @throws JRException
*/
public JRDataSource createDatasource() throws JRException;
/**
* Closes resources kept open during the data source iteration.
* <p/>
* This method is called after the report is filled or the dataset is iterated.
* If a resource is not needed after the data source has been created, it should be
* released at the end of {@link #createDatasource() createDatasource}.
*/
public void close();
/**
* Cancels the query if it's currently running.
* <p/>
* This method will be called from a different thread if the client decides to
* cancel the filling process.
*
* @return <code>true</code> if and only if the query was running and it has been canceled
* @throws JRException
*/
public boolean cancelQuery() throws JRException;
}