EnergyDatum.java

/* ==================================================================
 * EnergyDatum.java - Apr 1, 2014 5:02:29 PM
 * 
 * Copyright 2007-2014 SolarNetwork.net Dev Team
 * 
 * This program is free software; you can redistribute it and/or 
 * modify it under the terms of the GNU General Public License as 
 * published by the Free Software Foundation; either version 2 of 
 * the License, or (at your option) any later version.
 * 
 * This program 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 
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License 
 * along with this program; if not, write to the Free Software 
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 
 * 02111-1307 USA
 * ==================================================================
 */

package net.solarnetwork.node.domain;

/**
 * Standardized API for energy related datum to implement. By "energy" we simply
 * mean this datum represents information tracked during the production or
 * consumption of energy. For example current sensors can provide approximate
 * instantaneous watt readings, watt-hour meters can provide accumulated Wh
 * readings, and usually solar inverters can provide instantaneous generated
 * power and accumulated energy production readings.
 * 
 * @author matt
 * @version 1.1
 */
public interface EnergyDatum extends Datum {

	/**
	 * The {@link net.solarnetwork.domain.GeneralNodeDatumSamples} accumulating
	 * sample key for {@link #getWattHourReading()} values.
	 */
	public static final String WATT_HOUR_READING_KEY = "wattHours";

	/**
	 * The {@link net.solarnetwork.domain.GeneralNodeDatumSamples} instantaneous
	 * sample key for {@link #getWatts()} values.
	 */
	public static final String WATTS_KEY = "watts";

	/** A tag for "consumption" of energy. */
	public static final String TAG_CONSUMPTION = "consumption";

	/** A tag for "generation" of energy. */
	public static final String TAG_GENERATION = "power";

	/**
	 * Get a watt-hour reading. Generally this is an accumulating value and
	 * represents the overall energy used or produced since some reference date.
	 * Often the reference date if fixed, but it could also shift, for example
	 * shift to the last time a reading was taken.
	 * 
	 * @return the watt hour reading, or <em>null</em> if not available
	 */
	public Long getWattHourReading();

	/**
	 * Get the instantaneous watts.
	 * 
	 * @return watts, or <em>null</em> if not available
	 */
	public Integer getWatts();

}