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public interface TrendingDataChannel {

package org.glast.base.application.data.trending;

import org.glast.base.application.data.*;

/**
 *
 * @author The FreeHEP team @ SLAC
 *
 */
public interface TrendingDataChannel {

    /**
     * A TrendingDataChannel is any set of data and metadata that depends either on time directely
     * or on some time dependent variable, like release number, version number etc.
     *
     * The TrendingData provided by the TrendingDataChannel can either be in raw
     * or statistical format.
     * A raw TrendingDataChannel is a channel that, for any interval on the trending axis, 
     * can provide all the changes ever recorded in its trending data.
     * A statistical TrendingDataChannel is a channel that can only provide
     * statistical (accumulated) information of the changes in its trendable
     * data.
     * A raw TrendingDataChannel must always be able to provide data in statistical
     * format. This feature is fundamental for performance reasons when requesting data
     * over very long intervals in the trending axis where high levels of details
     * are not necessary.
     *
     * The TrendingData returned by a TrendingDataChannel contains data
     * and possibly metadata. The nature of the data and metadata depends on the
     * format of the request. Raw TrendingData should contain raw values while
     * statistical TrendingData should contain accumulated quantities like mean, 
     * rms, max value, min value etc.
     * The metadata is part of the TrendingData as it could also change over time.
     *
     * The TrendingDataChannel can have one or more trending axis; the axis could be
     * time, like milliseconds, Dates, Strings or any Object that defines some
     * ordering for the TrendingData.
     *
     * To retrieve some TrendingData it is necessary to provide a set of selection
     * criteria. 
     *
     **/
    
    public static String VALUE        = "value";
    public static String ERROR        = "error";
    public static String ERROR_PLUS   = "error_plus";
    public static String ERROR_MINUS  = "error_minus";
    public static String MEAN         = "mean";
    public static String RMS          = "rms";
    public static String MAX_VALUE    = "max_value";
    public static String MIN_VALUE    = "min_value";
    public static String TIME         = "time";
    public static String WARNING_LOW  = "warning_low";
    public static String WARNING_HIGH = "warning_high";
    public static String ALARM_LOW    = "alarm_low";
    public static String ALARM_HIGH   = "alarm_high";
    
    
    /**
     * The name of this channel.
     *
     */
    public String getName();
    
    /**
     * Check if a given channel can provide raw TrendingData.
     *
     **/
    public boolean getHasRawTrendingData();
    
    /**
     * Get the names of the provided raw data and metadata.
     *
     */
    public String[] getRawTrendingDataNames();
    public String[] getRawTrendingMetaDataNames();
    
    /**
     * Get the names of the provided statistical data and metadata.
     *
     */
    public String[] getStatisticalTrendingDataNames();
    public String[] getStatisticalTrendingMetaDataNames();
    
    /**
     * Get the names of the time axis for this channel.
     *
     */
    public String[] getTrendingAxisNames();
    
    /**
     *
     */
    public TrendingDataResult getTrendingData(TrendingAxisSelection selection);
    //Below we can add a selection on the data itself.
    //How does this work if the channels decides to ignore the selection type?
//    public TrendingDataResult getTrendingData(TrendingAxisSelection selection, TrendingDataSelection dataSelection);
     
}