Samuele Locatelli
439 lines
16 KiB
C#
439 lines
16 KiB
C#
/* ========================================================================
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* Copyright (c) 2005-2020 The OPC Foundation, Inc. All rights reserved.
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*
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* OPC Foundation MIT License 1.00
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*
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* Permission is hereby granted, free of charge, to any person
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* obtaining a copy of this software and associated documentation
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* files (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use,
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* copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following
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* conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*
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* The complete license agreement can be found here:
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* http://opcfoundation.org/License/MIT/1.00/
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* ======================================================================*/
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using System;
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using System.Collections.Generic;
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using System.Text;
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using Opc.Ua;
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namespace Quickstarts.ReferenceServer
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{
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/// <summary>
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/// Calculates the value of an aggregate.
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/// </summary>
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public class AggregateCalculator2
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{
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/// <summary>
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/// Initializes the calculation stream.
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/// </summary>
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/// <param name="startTime">The start time.</param>
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/// <param name="endTime">The end time.</param>
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/// <param name="processingInterval">The processing interval.</param>
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/// <param name="configuration">The aggregate configuration.</param>
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public void Initialize(
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DateTime startTime,
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DateTime endTime,
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double processingInterval,
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AggregateConfiguration configuration)
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{
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m_startTime = startTime;
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m_endTime = endTime;
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m_configuration = configuration;
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m_processingInterval = processingInterval;
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m_timeFlowsBackward = (endTime < startTime);
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m_values = new LinkedList<DataValue>();
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m_lastRawTimestamp = (m_timeFlowsBackward) ? DateTime.MaxValue : DateTime.MinValue;
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TimeSlice slice = new TimeSlice();
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slice.StartTime = startTime;
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slice.EndTime = slice.StartTime.AddMilliseconds((m_timeFlowsBackward) ? -m_processingInterval : m_processingInterval);
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slice.EarlyBound = null;
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slice.LateBound = null;
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slice.Complete = false;
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m_nextSlice = slice;
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}
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/// <summary>
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/// Pushes the next raw value into the stream.
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/// </summary>
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/// <param name="value">The data value to append to the stream.</param>
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/// <returns>True if successful, false if the source timestamp has been superceeded by values already in the stream.</returns>
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public bool PushRawValue(DataValue value)
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{
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if (value == null)
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{
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return false;
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}
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if (CompareTimestamps(value.SourceTimestamp, m_lastRawTimestamp) < 0)
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{
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return false;
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}
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LinkedListNode<DataValue> node = m_values.AddLast(value);
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m_lastRawTimestamp = value.SourceTimestamp;
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if (IsGood(value))
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{
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if (CompareTimestamps(m_lastRawTimestamp, m_nextSlice.StartTime) <= 0)
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{
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m_nextSlice.EarlyBound = node;
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}
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if (CompareTimestamps(m_lastRawTimestamp, m_nextSlice.EndTime) >= 0)
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{
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m_nextSlice.LateBound = node;
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m_nextSlice.Complete = true;
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}
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}
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return true;
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}
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/// <summary>
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/// Returns the next processed value.
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/// </summary>
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/// <param name="returnPartial">If true a partial interval should be processed.</param>
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/// <returns>The processed value. Null if nothing available and returnPartial is false.</returns>
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public DataValue GetProcessedValue(bool returnPartial)
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{
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// do nothing if slice not complete and partial values not requested.
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if (!m_nextSlice.Complete)
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{
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if (CompareTimestamps(m_endTime, m_nextSlice.EndTime) > 0)
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{
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if (!returnPartial)
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{
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return null;
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}
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}
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}
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// check for end.
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if (CompareTimestamps(m_endTime, m_nextSlice.StartTime) <= 0)
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{
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return null;
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}
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// compute the value.
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DataValue value = ComputeValue(m_nextSlice);
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TimeSlice slice = new TimeSlice();
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slice.StartTime = m_nextSlice.EndTime;
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slice.EndTime = slice.StartTime.AddMilliseconds((m_timeFlowsBackward) ? -m_processingInterval : m_processingInterval);
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slice.EarlyBound = FindEarlyBound(slice.StartTime);
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slice.LateBound = FindLateBound(slice.EarlyBound, slice.EndTime);
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slice.Complete = slice.LateBound != null;
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m_nextSlice = slice;
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// remove all data prior to the early bound.
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if (slice.EarlyBound != null)
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{
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LinkedListNode<DataValue> ii = slice.EarlyBound.Previous;
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while (ii != null)
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{
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LinkedListNode<DataValue> next = ii.Previous;
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m_values.Remove(ii);
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ii = next;
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}
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}
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return value;
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}
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/// <summary>
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/// Interpolates the value at the specified timestamp.
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/// </summary>
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/// <param name="timestamp">The timestamp to use,</param>
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/// <param name="start">The start position.</param>
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/// <returns>The interpolated value.</returns>
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private DataValue Interpolate(DateTime timestamp, LinkedListNode<DataValue> start)
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{
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if (start == null)
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{
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start = m_values.First;
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}
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if (start == null)
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{
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return new DataValue(Variant.Null, StatusCodes.BadNoData, timestamp, timestamp);
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}
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LinkedListNode<DataValue> firstBound = null;
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LinkedListNode<DataValue> lastBound = null;
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bool firstBoundBad = false;
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bool lastBoundBad = false;
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for (LinkedListNode<DataValue> ii = start; ii != null; ii = ii.Next)
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{
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int difference = CompareTimestamps(ii.Value.SourceTimestamp, timestamp);
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// check for an exact match.
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if (difference == 0)
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{
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if (IsGood(ii.Value))
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{
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return ii.Value;
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}
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}
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// find the first good value before the timestamp.
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if (difference <= 0)
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{
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if (IsGood(ii.Value))
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{
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firstBound = ii;
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}
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else
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{
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firstBoundBad = true;
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}
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}
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// find the first good value after the timestamp.
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if (difference >= 0)
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{
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if (IsGood(ii.Value))
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{
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lastBound = ii;
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break;
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}
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else
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{
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lastBoundBad = true;
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}
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}
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}
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// check if first bound found.
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if (firstBound == null)
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{
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// can't extrapolate backwards in time.
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if (!m_timeFlowsBackward)
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{
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return new DataValue(Variant.Null, StatusCodes.BadNoData, timestamp, timestamp);
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}
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}
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// check if last bound found.
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if (lastBound == null)
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{
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// can't extrapolate backwards in time.
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if (m_timeFlowsBackward)
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{
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return new DataValue(Variant.Null, StatusCodes.BadNoData, timestamp, timestamp);
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}
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}
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// use stepped interpolation/extrapolation if a bound is missing.
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if (!m_configuration.UseSlopedExtrapolation || lastBound == null || firstBound == null)
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{
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if (m_timeFlowsBackward)
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{
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StatusCode statusCode = (lastBoundBad) ? StatusCodes.UncertainDataSubNormal : StatusCodes.Good;
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statusCode = statusCode.SetAggregateBits(AggregateBits.Interpolated);
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return new DataValue(lastBound.Value.WrappedValue, statusCode, timestamp, timestamp);
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}
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else
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{
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StatusCode statusCode = (firstBoundBad) ? StatusCodes.UncertainDataSubNormal : StatusCodes.Good;
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statusCode = statusCode.SetAggregateBits(AggregateBits.Interpolated);
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return new DataValue(firstBound.Value.WrappedValue, statusCode, timestamp, timestamp);
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}
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}
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// calculate sloped interpolation.
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else
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{
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DataValue dataValue = new DataValue();
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dataValue.SourceTimestamp = timestamp;
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dataValue.ServerTimestamp = timestamp;
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try
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{
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// convert to doubles.
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TypeInfo sourceType = firstBound.Value.WrappedValue.TypeInfo;
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double firstValue = (double)TypeInfo.Cast(firstBound.Value.Value, sourceType, BuiltInType.Double);
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double lastValue = (double)TypeInfo.Cast(lastBound.Value.Value, lastBound.Value.WrappedValue.TypeInfo, BuiltInType.Double);
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// do interpolation.
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double range = (lastBound.Value.SourceTimestamp - firstBound.Value.SourceTimestamp).TotalMilliseconds;
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double slope = (lastValue - firstValue) / range;
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double doubleValue = slope * (timestamp - firstBound.Value.SourceTimestamp).TotalMilliseconds + firstValue;
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// convert back to original type.
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object value = TypeInfo.Cast(doubleValue, TypeInfo.Scalars.Double, sourceType.BuiltInType);
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dataValue.WrappedValue = new Variant(value, sourceType);
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}
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catch (Exception)
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{
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// handle data conversion error.
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return new DataValue(Variant.Null, StatusCodes.BadTypeMismatch, timestamp, timestamp);
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}
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// set the aggregate bits as required.
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StatusCode statusCode = (firstBoundBad || lastBoundBad) ? StatusCodes.UncertainDataSubNormal : StatusCodes.Good;
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dataValue.StatusCode = statusCode.SetAggregateBits(AggregateBits.Interpolated);
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return dataValue;
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}
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}
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/// <summary>
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/// Computes the value for the timeslice.
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/// </summary>
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/// <param name="slice">The time slice to use for the computation.</param>
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/// <returns>The value for the time slice.</returns>
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protected DataValue ComputeValue(TimeSlice slice)
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{
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return Interpolate(slice.StartTime, slice.EarlyBound);
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}
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/// <summary>
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/// Finds the early bound for the timestamp.
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/// </summary>
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/// <param name="timestamp">The timestamp to search.</param>
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/// <returns>The first good value that preceeds the timestamp.</returns>
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private LinkedListNode<DataValue> FindEarlyBound(DateTime timestamp)
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{
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for (LinkedListNode<DataValue> ii = m_values.Last; ii != null; ii = ii.Previous)
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{
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if (IsGood(ii.Value))
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{
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if (CompareTimestamps(ii.Value.SourceTimestamp, timestamp) <= 0)
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{
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return ii;
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}
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}
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}
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return null;
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}
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/// <summary>
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/// Finds the late bound for the timestamp.
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/// </summary>
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/// <param name="start">The starting point for the search.</param>
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/// <param name="timestamp">The timestamp to search.</param>
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/// <returns>The first good value that follows the timestamp.</returns>
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private LinkedListNode<DataValue> FindLateBound(LinkedListNode<DataValue> start, DateTime timestamp)
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{
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if (start == null)
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{
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start = m_values.First;
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}
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if (start == null)
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{
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return null;
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}
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for (LinkedListNode<DataValue> ii = start; ii != null; ii = ii.Next)
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{
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if (IsGood(ii.Value))
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{
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if (CompareTimestamps(ii.Value.SourceTimestamp, timestamp) >= 0)
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{
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return ii;
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}
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}
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}
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return null;
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}
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/// <summary>
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/// Detremines the relative position of two timestamps in the stream.
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/// </summary>
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/// <param name="timestamp1">The first timestamp.</param>
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/// <param name="timestamp2">The second timestamp.</param>
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/// <returns>
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/// Returns less than zero if timestamp1 preceeds timestamp2
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/// Returns greater than zero if timestamp2 preceeds timestamp1
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/// Returns zero if timestamp1 equals timestamp2
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/// </returns>
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public int CompareTimestamps(DateTime timestamp1, DateTime timestamp2)
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{
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int difference = timestamp1.CompareTo(timestamp2);
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if (difference == 0)
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{
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return 0;
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}
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if (m_timeFlowsBackward)
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{
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return -difference;
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}
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return difference;
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}
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/// <summary>
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/// Checks if the value is good according to the configuration rules.
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/// </summary>
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/// <param name="value">The value to test.</param>
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/// <returns>True if the value is good.</returns>
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public bool IsGood(DataValue value)
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{
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if (value == null)
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{
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return false;
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}
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if (m_configuration.TreatUncertainAsBad)
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{
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if (StatusCode.IsNotGood(value.StatusCode))
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{
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return false;
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}
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}
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else
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{
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if (StatusCode.IsBad(value.StatusCode))
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{
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return false;
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}
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}
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return true;
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}
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protected class TimeSlice
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{
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public DateTime StartTime { get; set; }
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public DateTime EndTime { get; set; }
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public LinkedListNode<DataValue> EarlyBound;
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public LinkedListNode<DataValue> LateBound;
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public bool Complete { get; set; }
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}
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private TimeSlice m_nextSlice;
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private AggregateConfiguration m_configuration;
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private DateTime m_lastRawTimestamp;
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private double m_processingInterval;
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private bool m_timeFlowsBackward;
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private LinkedList<DataValue> m_values;
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private DateTime m_startTime;
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private DateTime m_endTime;
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}
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}
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