/*******************************************************************************
 * Copyright (c) 2001-2005 Sasa Markovic and Ciaran Treanor.
 * Copyright (c) 2011 The OpenNMS Group, Inc.
 *
 * This library 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 2.1 of the License, or (at your option) any later version.
 *
 * This library 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 this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *******************************************************************************/
package org.jrobin.data;

/**
 * <p>Interface to be used for custom datasources.
 * If you wish to use a custom datasource in a graph, you should create a class implementing this interface
 * that represents that datasource, and then pass this class on to the RrdGraphDef.</p>
 */
public abstract class Plottable {
	/**
	 * Retrieves datapoint value based on a given timestamp.
	 * Use this method if you only have one series of data in this class.
	 *
	 * @param timestamp Timestamp in seconds for the datapoint.
	 * @return Double value of the datapoint.
	 */
	public double getValue(long timestamp) {
		return Double.NaN;
	}
}
