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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.
A TrendingDataChannel is not required to evaluate "accurate" statistical information over any time-variable interval; statistical data might be pre-calculated on some granularity and requests over a finer grid might obtain an approximated result.
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.
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To retrieve some TrendingData it is necessary to provide a set of selection criteriaTrendingAxisSelection object.
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public interface TrendingDataChannel {
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();
/**
*
Get the TrendingData for */
a public TrendingDataResult getTrendingData(TrendingAxisSelection selection);given TrendingAxisSelection.
//Below we* canThe addTrendingData ais selectioncontained onin thea dataTrendingDataResult itselfobject.
//How does this work if*
the channels decides to ignore the selection type?
// */
public TrendingDataResult getTrendingData(TrendingAxisSelection selection, TrendingDataSelection dataSelection);
}
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