/// <summary>
/// Read historian data from server.
/// </summary>
/// <param name="connection">openHistorian connection.</param>
/// <param name="startTime">Start time of query.</param>
/// <param name="stopTime">Stop time of query.</param>
/// <param name="measurementIDs">Array of measurement IDs to query - or <c>null</c> for all available points.</param>
/// <param name="resolution">Resolution for data query.</param>
/// <returns>Enumeration of <see cref="IMeasurement"/> values read for time range.</returns>
/// <remarks>
/// <example>
/// <code>
/// using (var connection = new Connection("127.0.0.1", "PPA"))
/// foreach(var measurement in GetHistorianData(connection, DateTime.UtcNow.AddMinutes(-1.0D), DateTime.UtcNow))
/// Console.WriteLine("{0}:{1} @ {2} = {3}, quality: {4}", measurement.Key.Source, measurement.Key.ID, measurement.Timestamp, measurement.Value, measurement.StateFlags);
/// </code>
/// </example>
/// </remarks>
public static IEnumerable <IMeasurement> GetHistorianData(Connection connection, DateTime startTime, DateTime stopTime, IEnumerable <ulong> measurementIDs = null, Resolution resolution = Resolution.Full)
{
SeekFilterBase <HistorianKey> timeFilter;
MatchFilterBase <HistorianKey, HistorianValue> pointFilter = null;
HistorianKey key = new HistorianKey();
HistorianValue value = new HistorianValue();
// Set data scan resolution
if (resolution == Resolution.Full)
{
timeFilter = TimestampSeekFilter.CreateFromRange <HistorianKey>(startTime, stopTime);
}
else
{
TimeSpan resolutionInterval = resolution.GetInterval();
BaselineTimeInterval interval = BaselineTimeInterval.Second;
if (resolutionInterval.Ticks < Ticks.PerMinute)
{
interval = BaselineTimeInterval.Second;
}
else if (resolutionInterval.Ticks < Ticks.PerHour)
{
interval = BaselineTimeInterval.Minute;
}
else if (resolutionInterval.Ticks == Ticks.PerHour)
{
interval = BaselineTimeInterval.Hour;
}
startTime = startTime.BaselinedTimestamp(interval);
stopTime = stopTime.BaselinedTimestamp(interval);
timeFilter = TimestampSeekFilter.CreateFromIntervalData <HistorianKey>(startTime, stopTime, resolutionInterval, new TimeSpan(TimeSpan.TicksPerMillisecond));
}
// Setup point ID selections
if (measurementIDs != null)
{
pointFilter = PointIdMatchFilter.CreateFromList <HistorianKey, HistorianValue>(measurementIDs);
}
// Start stream reader for the provided time window and selected points
using (Database database = connection.OpenDatabase())
{
TreeStream <HistorianKey, HistorianValue> stream = database.Read(SortedTreeEngineReaderOptions.Default, timeFilter, pointFilter);
while (stream.Read(key, value))
{
yield return new Measurement
{
Metadata = MeasurementKey.LookUpOrCreate(connection.InstanceName, (uint)key.PointID).Metadata,
Timestamp = key.TimestampAsDate,
Value = value.AsSingle,
StateFlags = (MeasurementStateFlags)value.Value3
}
}
;
}
}
