///// <summary>
///// Establish measurement key cache based on received meta-data.
///// </summary>
///// <param name="metadata">Meta-data received from a subscription.</param>
///// <param name="instanceName">Instance name of the historian.</param>
///// <remarks>
///// If you want the <see cref="IMeasurement.Key"/> values that are returned from a <see cref="GetHistorianData"/> query
///// to have properly assigned Guid based signal IDs, i.e., <see cref="MeasurementKey.SignalID"/>, establish the
///// measurement key cache as soon as you have received meta-data from a GEP subscription query.
///// </remarks>
/// <summary>
/// Reads interpolated 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="interval">The sampling interval for the interpolated data.</param>
/// <param name="measurementIDs">Comma separated list of measurement IDs to 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 GetInterpolatedData(connection, DateTime.UtcNow.AddMinutes(-1.0D), DateTime.UtcNow, TimeSpan.FromSeconds(2.0D), "7,5,15"))
/// 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> GetInterpolatedData(Connection connection, DateTime startTime, DateTime stopTime, TimeSpan interval, string measurementIDs)
{
if ((object)measurementIDs == null)
{
throw new ArgumentNullException(nameof(measurementIDs));
}
// TODO: This was based on code that aligns data and fills time - this function will
// need to be re-worked to provide data on an interval based on slopes and time...
Measurement[] values = measurementIDs.Split(',').Select(uint.Parse).Select(id => new Measurement()
{
Metadata = MeasurementKey.LookUpBySource(connection.InstanceName, id).Metadata
}).ToArray();
long tickInterval = interval.Ticks;
long lastTimestamp = 0L;
foreach (IMeasurement measurement in GetHistorianData(connection, startTime, stopTime, measurementIDs))
{
long timestamp = measurement.Timestamp;
// Start a new row for each encountered new timestamp
if (timestamp != lastTimestamp)
{
if (lastTimestamp > 0)
{
foreach (IMeasurement value in values)
{
yield return(value);
}
}
for (int i = 0; i < values.Length; i++)
{
values[i] = Measurement.Clone(values[i]);
}
if (lastTimestamp > 0 && timestamp > lastTimestamp)
{
long difference = timestamp - lastTimestamp;
if (difference > tickInterval)
{
long interpolated = lastTimestamp;
for (long i = 1; i < difference / tickInterval; i++)
{
interpolated = interpolated + tickInterval;
foreach (IMeasurement value in values)
{
yield return(value);
}
}
}
}
lastTimestamp = timestamp;
}
}
}