/// <summary>
/// Releases any continuation points.
/// </summary>
private void ReleaseContinuationPoints()
{
if (m_details != null)
{
HistoryReadValueIdCollection nodesToRead = new HistoryReadValueIdCollection();
nodesToRead.Add(m_nodeToRead);
HistoryReadResultCollection results = null;
DiagnosticInfoCollection diagnosticInfos = null;
m_session.HistoryRead(
null,
new ExtensionObject(m_details),
TimestampsToReturn.Neither,
true,
nodesToRead,
out results,
out diagnosticInfos);
Session.ValidateResponse(results, nodesToRead);
Session.ValidateDiagnosticInfos(diagnosticInfos, nodesToRead);
NextBTN.Visible = false;
StopBTN.Enabled = false;
GoBTN.Visible = true;
m_details = null;
m_nodeToRead = null;
}
}
/// <summary>
/// Starts a new read operation.
/// </summary>
private void ReadFirst()
{
ResultsLV.ClearEventHistory();
// set up the request parameters.
ReadEventDetails details = new ReadEventDetails();
details.StartTime = DateTime.MinValue;
details.EndTime = DateTime.MinValue;
details.NumValuesPerNode = 0;
details.Filter = m_filter.GetFilter();
if (StartTimeCK.Checked)
{
details.StartTime = StartTimeDP.Value.ToUniversalTime();
}
if (EndTimeCK.Checked)
{
details.EndTime = EndTimeDP.Value.ToUniversalTime();
}
if (MaxReturnValuesCK.Checked)
{
details.NumValuesPerNode = (uint)MaxReturnValuesNP.Value;
}
// read the events from the server.
HistoryReadValueId nodeToRead = new HistoryReadValueId();
nodeToRead.NodeId = m_areaId;
ReadNext(details, nodeToRead);
}
private ExtensionObject ReadEventDetails()
{
ReadEventDetails details = new ReadEventDetails {
NumValuesPerNode = 10,
StartTime = DateTime.UtcNow.AddSeconds(30),
EndTime = DateTime.UtcNow.AddHours(-1),
};
return(new ExtensionObject(details));
}
/// <summary>
/// Continues a read operation.
/// </summary>
private void ReadNext(ReadEventDetails details, HistoryReadValueId nodeToRead)
{
HistoryReadValueIdCollection nodesToRead = new HistoryReadValueIdCollection();
nodesToRead.Add(nodeToRead);
HistoryReadResultCollection results = null;
DiagnosticInfoCollection diagnosticInfos = null;
ResponseHeader responseHeader = m_session.HistoryRead(
null,
new ExtensionObject(details),
TimestampsToReturn.Neither,
false,
nodesToRead,
out results,
out diagnosticInfos);
Session.ValidateResponse(results, nodesToRead);
Session.ValidateDiagnosticInfos(diagnosticInfos, nodesToRead);
if (StatusCode.IsBad(results[0].StatusCode))
{
throw ServiceResultException.Create(results[0].StatusCode, 0, diagnosticInfos, responseHeader.StringTable);
}
// display results.
HistoryEvent data = ExtensionObject.ToEncodeable(results[0].HistoryData) as HistoryEvent;
ResultsLV.AddEventHistory(data);
// check if a continuation point exists.
if (results[0].ContinuationPoint != null && results[0].ContinuationPoint.Length > 0)
{
nodeToRead.ContinuationPoint = results[0].ContinuationPoint;
NextBTN.Visible = true;
StopBTN.Enabled = true;
GoBTN.Visible = false;
m_details = details;
m_nodeToRead = nodeToRead;
}
// all done.
else
{
NextBTN.Visible = false;
StopBTN.Enabled = false;
GoBTN.Visible = true;
m_details = null;
m_nodeToRead = null;
}
}
/// <summary>
/// Fetches the recent history.
/// </summary>
private void ReadHistory(ReadEventDetails details, NodeId areaId)
{
HistoryReadValueIdCollection nodesToRead = new HistoryReadValueIdCollection();
HistoryReadValueId nodeToRead = new HistoryReadValueId();
nodeToRead.NodeId = areaId;
nodesToRead.Add(nodeToRead);
HistoryReadResultCollection results = null;
DiagnosticInfoCollection diagnosticInfos = null;
m_session.HistoryRead(
null,
new ExtensionObject(details),
TimestampsToReturn.Neither,
false,
nodesToRead,
out results,
out diagnosticInfos);
ClientBase.ValidateResponse(results, nodesToRead);
ClientBase.ValidateDiagnosticInfos(diagnosticInfos, nodesToRead);
if (StatusCode.IsBad(results[0].StatusCode))
{
throw new ServiceResultException(results[0].StatusCode);
}
HistoryEvent events = ExtensionObject.ToEncodeable(results[0].HistoryData) as HistoryEvent;
foreach (HistoryEventFieldList e in events.Events)
{
DisplayEvent(e.EventFields);
}
// release continuation points.
if (results[0].ContinuationPoint != null && results[0].ContinuationPoint.Length > 0)
{
nodeToRead.ContinuationPoint = results[0].ContinuationPoint;
m_session.HistoryRead(
null,
new ExtensionObject(details),
TimestampsToReturn.Neither,
true,
nodesToRead,
out results,
out diagnosticInfos);
}
}
/// <summary>
/// Fetches the recent history.
/// </summary>
private void ReadRecentHistory()
{
// check if session is active.
if (m_session != null)
{
// check if area supports history.
IObject area = m_session.NodeCache.Find(m_areaId) as IObject;
if (area != null && ((area.EventNotifier & EventNotifiers.HistoryRead) != 0))
{
// get the last hour or 10 events.
ReadEventDetails details = new ReadEventDetails();
details.StartTime = DateTime.UtcNow.AddSeconds(30);
details.EndTime = details.StartTime.AddHours(-1);
details.NumValuesPerNode = 10;
details.Filter = m_filter.GetFilter();
// read the history.
ReadHistory(details, m_areaId);
}
}
}
/// <summary>
/// Returns the UTC timestamp of the first event in the archive.
/// </summary>
private DateTime ReadFirstDate()
{
// read the time of the first event in the archive.
ReadEventDetails details = new ReadEventDetails();
details.StartTime = new DateTime(1970, 1, 1);
details.EndTime = DateTime.MinValue;
details.NumValuesPerNode = 1;
details.Filter = new EventFilter();
details.Filter.AddSelectClause(Opc.Ua.ObjectTypeIds.BaseEventType, Opc.Ua.BrowseNames.Time);
HistoryReadValueId nodeToRead = new HistoryReadValueId();
nodeToRead.NodeId = m_areaId;
HistoryReadValueIdCollection nodesToRead = new HistoryReadValueIdCollection();
nodesToRead.Add(nodeToRead);
HistoryReadResultCollection results = null;
DiagnosticInfoCollection diagnosticInfos = null;
m_session.HistoryRead(
null,
new ExtensionObject(details),
TimestampsToReturn.Neither,
false,
nodesToRead,
out results,
out diagnosticInfos);
Session.ValidateResponse(results, nodesToRead);
Session.ValidateDiagnosticInfos(diagnosticInfos, nodesToRead);
if (StatusCode.IsBad(results[0].StatusCode))
{
throw new ServiceResultException(results[0].StatusCode);
}
// get the data.
HistoryEvent data = ExtensionObject.ToEncodeable(results[0].HistoryData) as HistoryEvent;
// release the continuation point.
if (results[0].ContinuationPoint != null)
{
nodeToRead.ContinuationPoint = results[0].ContinuationPoint;
m_session.HistoryRead(
null,
new ExtensionObject(details),
TimestampsToReturn.Neither,
true,
nodesToRead,
out results,
out diagnosticInfos);
Session.ValidateResponse(results, nodesToRead);
Session.ValidateDiagnosticInfos(diagnosticInfos, nodesToRead);
}
// check if an event found.
if (data == null || data.Events.Count == 0 || data.Events[0].EventFields.Count == 0)
{
throw new ServiceResultException(StatusCodes.BadNoDataAvailable);
}
// get the event time.
DateTime? eventTime = data.Events[0].EventFields[0].Value as DateTime?;
if (eventTime == null)
{
throw new ServiceResultException(StatusCodes.BadTypeMismatch);
}
// return time as UTC value.
return eventTime.Value;
}
/// <summary>
/// Releases any continuation points.
/// </summary>
private void ReleaseContinuationPoints()
{
if (m_details != null)
{
HistoryReadValueIdCollection nodesToRead = new HistoryReadValueIdCollection();
nodesToRead.Add(m_nodeToRead);
HistoryReadResultCollection results = null;
DiagnosticInfoCollection diagnosticInfos = null;
m_session.HistoryRead(
null,
new ExtensionObject(m_details),
TimestampsToReturn.Neither,
true,
nodesToRead,
out results,
out diagnosticInfos);
Session.ValidateResponse(results, nodesToRead);
Session.ValidateDiagnosticInfos(diagnosticInfos, nodesToRead);
NextBTN.Visible = false;
StopBTN.Enabled = false;
GoBTN.Visible = true;
m_details = null;
m_nodeToRead = null;
}
}
/// <summary>
/// Reads history events.
/// </summary>
protected virtual void HistoryReadEvents(
ServerSystemContext context,
ReadEventDetails details,
TimestampsToReturn timestampsToReturn,
IList<HistoryReadValueId> nodesToRead,
IList<HistoryReadResult> results,
IList<ServiceResult> errors,
List<NodeHandle> nodesToProcess,
IDictionary<NodeId, NodeState> cache)
{
for (int ii = 0; ii < nodesToProcess.Count; ii++)
{
NodeHandle handle = nodesToProcess[ii];
// validate node.
NodeState source = ValidateNode(context, handle, cache);
if (source == null)
{
continue;
}
errors[handle.Index] = StatusCodes.BadHistoryOperationUnsupported;
}
}
/// <summary>
/// Creates a new history request.
/// </summary>
private HistoryReadRequest CreateHistoryReadRequest(
ServerSystemContext context,
ReadEventDetails details,
NodeHandle handle,
HistoryReadValueId nodeToRead)
{
FilterContext filterContext = new FilterContext(context.NamespaceUris, context.TypeTable, context.PreferredLocales);
LinkedList <BaseEventState> events = new LinkedList <BaseEventState>();
for (ReportType ii = ReportType.FluidLevelTest; ii <= ReportType.InjectionTest; ii++)
{
DataView view = null;
if (handle.Node is WellState)
{
view = m_generator.ReadHistoryForWellId(
ii,
(string)handle.Node.NodeId.Identifier,
details.StartTime,
details.EndTime);
}
else
{
view = m_generator.ReadHistoryForArea(
ii,
handle.Node.NodeId.Identifier as string,
details.StartTime,
details.EndTime);
}
LinkedListNode <BaseEventState> pos = events.First;
bool sizeLimited = (details.StartTime == DateTime.MinValue || details.EndTime == DateTime.MinValue);
foreach (DataRowView row in view)
{
// check if reached max results.
if (sizeLimited)
{
if (events.Count >= details.NumValuesPerNode)
{
break;
}
}
BaseEventState e = m_generator.GetReport(context, NamespaceIndex, ii, row.Row);
if (details.Filter.WhereClause != null && details.Filter.WhereClause.Elements.Count > 0)
{
if (!details.Filter.WhereClause.Evaluate(filterContext, e))
{
continue;
}
}
bool inserted = false;
for (LinkedListNode <BaseEventState> jj = pos; jj != null; jj = jj.Next)
{
if (jj.Value.Time.Value > e.Time.Value)
{
events.AddBefore(jj, e);
pos = jj;
inserted = true;
break;
}
}
if (!inserted)
{
events.AddLast(e);
pos = null;
}
}
}
HistoryReadRequest request = new HistoryReadRequest();
request.Events = events;
request.TimeFlowsBackward = details.StartTime == DateTime.MinValue || (details.EndTime != DateTime.MinValue && details.EndTime < details.StartTime);
request.NumValuesPerNode = details.NumValuesPerNode;
request.Filter = details.Filter;
request.FilterContext = filterContext;
return(request);
}
/// <summary>
/// Reads history events.
/// </summary>
protected override void HistoryReadEvents(
ServerSystemContext context,
ReadEventDetails details,
TimestampsToReturn timestampsToReturn,
IList <HistoryReadValueId> nodesToRead,
IList <HistoryReadResult> results,
IList <ServiceResult> errors,
List <NodeHandle> nodesToProcess,
IDictionary <NodeId, NodeState> cache)
{
for (int ii = 0; ii < nodesToProcess.Count; ii++)
{
NodeHandle handle = nodesToProcess[ii];
HistoryReadValueId nodeToRead = nodesToRead[handle.Index];
HistoryReadResult result = results[handle.Index];
HistoryReadRequest request = null;
// load an exising request.
if (nodeToRead.ContinuationPoint != null)
{
request = LoadContinuationPoint(context, nodeToRead.ContinuationPoint);
if (request == null)
{
errors[handle.Index] = StatusCodes.BadContinuationPointInvalid;
continue;
}
}
// create a new request.
else
{
request = CreateHistoryReadRequest(
context,
details,
handle,
nodeToRead);
}
// process events until the max is reached.
HistoryEvent events = new HistoryEvent();
while (request.NumValuesPerNode == 0 || events.Events.Count < request.NumValuesPerNode)
{
if (request.Events.Count == 0)
{
break;
}
BaseEventState e = null;
if (request.TimeFlowsBackward)
{
e = request.Events.Last.Value;
request.Events.RemoveLast();
}
else
{
e = request.Events.First.Value;
request.Events.RemoveFirst();
}
events.Events.Add(GetEventFields(request, e));
}
errors[handle.Index] = ServiceResult.Good;
// check if a continuation point is requred.
if (request.Events.Count > 0)
{
// only set if both end time and start time are specified.
if (details.StartTime != DateTime.MinValue && details.EndTime != DateTime.MinValue)
{
result.ContinuationPoint = SaveContinuationPoint(context, request);
}
}
// check if no data returned.
else
{
errors[handle.Index] = StatusCodes.GoodNoData;
}
// return the data.
result.HistoryData = new ExtensionObject(events);
}
}
/// <summary>
/// Creates a new history request.
/// </summary>
private HistoryReadRequest CreateHistoryReadRequest(
ServerSystemContext context,
ReadEventDetails details,
NodeHandle handle,
HistoryReadValueId nodeToRead)
{
FilterContext filterContext = new FilterContext(context.NamespaceUris, context.TypeTable, context.PreferredLocales);
LinkedList<BaseEventState> events = new LinkedList<BaseEventState>();
for (ReportType ii = ReportType.FluidLevelTest; ii <= ReportType.InjectionTest; ii++)
{
DataView view = null;
if (handle.Node is WellState)
{
view = m_generator.ReadHistoryForWellId(
ii,
(string)handle.Node.NodeId.Identifier,
details.StartTime,
details.EndTime);
}
else
{
view = m_generator.ReadHistoryForArea(
ii,
handle.Node.NodeId.Identifier as string,
details.StartTime,
details.EndTime);
}
LinkedListNode<BaseEventState> pos = events.First;
bool sizeLimited = (details.StartTime == DateTime.MinValue || details.EndTime == DateTime.MinValue);
foreach (DataRowView row in view)
{
// check if reached max results.
if (sizeLimited)
{
if (events.Count >= details.NumValuesPerNode)
{
break;
}
}
BaseEventState e = m_generator.GetReport(context, NamespaceIndex, ii, row.Row);
if (details.Filter.WhereClause != null && details.Filter.WhereClause.Elements.Count > 0)
{
if (!details.Filter.WhereClause.Evaluate(filterContext, e))
{
continue;
}
}
bool inserted = false;
for (LinkedListNode<BaseEventState> jj = pos; jj != null; jj = jj.Next)
{
if (jj.Value.Time.Value > e.Time.Value)
{
events.AddBefore(jj, e);
pos = jj;
inserted = true;
break;
}
}
if (!inserted)
{
events.AddLast(e);
pos = null;
}
}
}
HistoryReadRequest request = new HistoryReadRequest();
request.Events = events;
request.TimeFlowsBackward = details.StartTime == DateTime.MinValue || (details.EndTime != DateTime.MinValue && details.EndTime < details.StartTime);
request.NumValuesPerNode = details.NumValuesPerNode;
request.Filter = details.Filter;
request.FilterContext = filterContext;
return request;
}
/// <summary>
/// Fetches the recent history.
/// </summary>
private void ReadRecentHistory()
{
// check if session is active.
if (m_session != null)
{
// check if area supports history.
IObject area = m_session.NodeCache.Find(m_areaId) as IObject;
if (area != null && ((area.EventNotifier & EventNotifiers.HistoryRead) != 0))
{
// get the last hour or 10 events.
ReadEventDetails details = new ReadEventDetails();
details.StartTime = DateTime.UtcNow.AddSeconds(30);
details.EndTime = details.StartTime.AddHours(-1);
details.NumValuesPerNode = 10;
details.Filter = m_filter.GetFilter();
// read the history.
ReadHistory(details, m_areaId);
}
}
}
/// <summary>
/// Starts a new read operation.
/// </summary>
private void ReadFirst()
{
ResultsLV.ClearEventHistory();
// set up the request parameters.
ReadEventDetails details = new ReadEventDetails();
details.StartTime = DateTime.MinValue;
details.EndTime = DateTime.MinValue;
details.NumValuesPerNode = 0;
details.Filter = m_filter.GetFilter();
if (StartTimeCK.Checked)
{
details.StartTime = StartTimeDP.Value.ToUniversalTime();
}
if (EndTimeCK.Checked)
{
details.EndTime = EndTimeDP.Value.ToUniversalTime();
}
if (MaxReturnValuesCK.Checked)
{
details.NumValuesPerNode = (uint)MaxReturnValuesNP.Value;
}
// read the events from the server.
HistoryReadValueId nodeToRead = new HistoryReadValueId();
nodeToRead.NodeId = m_areaId;
ReadNext(details, nodeToRead);
}
/// <summary>
/// Fetches the recent history.
/// </summary>
private void ReadHistory(ReadEventDetails details, NodeId areaId)
{
HistoryReadValueIdCollection nodesToRead = new HistoryReadValueIdCollection();
HistoryReadValueId nodeToRead = new HistoryReadValueId();
nodeToRead.NodeId = areaId;
nodesToRead.Add(nodeToRead);
HistoryReadResultCollection results = null;
DiagnosticInfoCollection diagnosticInfos = null;
m_session.HistoryRead(
null,
new ExtensionObject(details),
TimestampsToReturn.Neither,
false,
nodesToRead,
out results,
out diagnosticInfos);
ClientBase.ValidateResponse(results, nodesToRead);
ClientBase.ValidateDiagnosticInfos(diagnosticInfos, nodesToRead);
if (StatusCode.IsBad(results[0].StatusCode))
{
throw new ServiceResultException(results[0].StatusCode);
}
HistoryEvent events = ExtensionObject.ToEncodeable(results[0].HistoryData) as HistoryEvent;
AddEventHistory(events);
// release continuation points.
if (results[0].ContinuationPoint != null && results[0].ContinuationPoint.Length > 0)
{
nodeToRead.ContinuationPoint = results[0].ContinuationPoint;
m_session.HistoryRead(
null,
new ExtensionObject(details),
TimestampsToReturn.Neither,
true,
nodesToRead,
out results,
out diagnosticInfos);
}
}
/// <summary>
/// Returns the UTC timestamp of the first event in the archive.
/// </summary>
private DateTime ReadFirstDate()
{
// read the time of the first event in the archive.
ReadEventDetails details = new ReadEventDetails();
details.StartTime = new DateTime(1970, 1, 1);
details.EndTime = DateTime.MinValue;
details.NumValuesPerNode = 1;
details.Filter = new EventFilter();
details.Filter.AddSelectClause(Opc.Ua.ObjectTypeIds.BaseEventType, Opc.Ua.BrowseNames.Time);
HistoryReadValueId nodeToRead = new HistoryReadValueId();
nodeToRead.NodeId = m_areaId;
HistoryReadValueIdCollection nodesToRead = new HistoryReadValueIdCollection();
nodesToRead.Add(nodeToRead);
HistoryReadResultCollection results = null;
DiagnosticInfoCollection diagnosticInfos = null;
m_session.HistoryRead(
null,
new ExtensionObject(details),
TimestampsToReturn.Neither,
false,
nodesToRead,
out results,
out diagnosticInfos);
Session.ValidateResponse(results, nodesToRead);
Session.ValidateDiagnosticInfos(diagnosticInfos, nodesToRead);
if (StatusCode.IsBad(results[0].StatusCode))
{
throw new ServiceResultException(results[0].StatusCode);
}
// get the data.
HistoryEvent data = ExtensionObject.ToEncodeable(results[0].HistoryData) as HistoryEvent;
// release the continuation point.
if (results[0].ContinuationPoint != null)
{
nodeToRead.ContinuationPoint = results[0].ContinuationPoint;
m_session.HistoryRead(
null,
new ExtensionObject(details),
TimestampsToReturn.Neither,
true,
nodesToRead,
out results,
out diagnosticInfos);
Session.ValidateResponse(results, nodesToRead);
Session.ValidateDiagnosticInfos(diagnosticInfos, nodesToRead);
}
// check if an event found.
if (data == null || data.Events.Count == 0 || data.Events[0].EventFields.Count == 0)
{
throw new ServiceResultException(StatusCodes.BadNoDataAvailable);
}
// get the event time.
DateTime?eventTime = data.Events[0].EventFields[0].Value as DateTime?;
if (eventTime == null)
{
throw new ServiceResultException(StatusCodes.BadTypeMismatch);
}
// return time as UTC value.
return(eventTime.Value);
}
/// <summary>
/// Encode historic events
/// </summary>
/// <param name="ct"></param>
/// <returns></returns>
private async Task EncodeHistoricEventsAsync(CancellationToken ct)
{
EventFilter filter = null;
try {
filter = await ReadEventFilterAsync(ct);
}
catch (Exception ex) {
_logger.Error(ex, "Failed to retrieve event filter for {nodeId}", _nodeId);
}
if (filter == null)
{
// Nothing to do without event filter
// TODO: use generates events? What other way to get event field structure?
return;
}
var details = new ReadEventDetails {
NumValuesPerNode = (uint)_maxValues,
// Read from today backward
EndTime = _startTime,
StartTime = _endTime,
Filter = filter
};
//
// Read first and retry with lower number of nodes to fix issues with
// misbehaving servers such as reference stack server.
//
byte[] continuationToken = null;
while (true)
{
ct.ThrowIfCancellationRequested();
try {
var result = await ReadHistoryAsync <HistoryEvent>(details, ct);
if (result.history?.Events != null)
{
_logger.Verbose(" {count} events...",
result.history.Events.Count);
foreach (var data in result.history.Events)
{
_encoder.WriteEncodeable(null, data, data.GetType());
_count++;
}
}
continuationToken = result.continuationToken;
break;
}
catch (FormatException) {
if (details.NumValuesPerNode == 0)
{
details.NumValuesPerNode = ushort.MaxValue;
}
else
{
details.NumValuesPerNode /= 2;
}
}
}
// Continue reading
while (continuationToken != null && _count < _maxValues)
{
// Continue reading history
ct.ThrowIfCancellationRequested();
var result = await ReadHistoryAsync <HistoryEvent>(details, ct,
continuationToken);
if (result.history?.Events != null)
{
_logger.Verbose("+ {count} events...",
result.history.Events.Count);
foreach (var data in result.history.Events)
{
_encoder.WriteEncodeable(null, data, data.GetType());
_count++;
}
}
continuationToken = result.continuationToken;
}
}
/// <summary>
/// Continues a read operation.
/// </summary>
private void ReadNext(ReadEventDetails details, HistoryReadValueId nodeToRead)
{
HistoryReadValueIdCollection nodesToRead = new HistoryReadValueIdCollection();
nodesToRead.Add(nodeToRead);
HistoryReadResultCollection results = null;
DiagnosticInfoCollection diagnosticInfos = null;
ResponseHeader responseHeader = m_session.HistoryRead(
null,
new ExtensionObject(details),
TimestampsToReturn.Neither,
false,
nodesToRead,
out results,
out diagnosticInfos);
Session.ValidateResponse(results, nodesToRead);
Session.ValidateDiagnosticInfos(diagnosticInfos, nodesToRead);
if (StatusCode.IsBad(results[0].StatusCode))
{
throw ServiceResultException.Create(results[0].StatusCode, 0, diagnosticInfos, responseHeader.StringTable);
}
// display results.
HistoryEvent data = ExtensionObject.ToEncodeable(results[0].HistoryData) as HistoryEvent;
ResultsLV.AddEventHistory(data);
// check if a continuation point exists.
if (results[0].ContinuationPoint != null && results[0].ContinuationPoint.Length > 0)
{
nodeToRead.ContinuationPoint = results[0].ContinuationPoint;
NextBTN.Visible = true;
StopBTN.Enabled = true;
GoBTN.Visible = false;
m_details = details;
m_nodeToRead = nodeToRead;
}
// all done.
else
{
NextBTN.Visible = false;
StopBTN.Enabled = false;
GoBTN.Visible = true;
m_details = null;
m_nodeToRead = null;
}
}
/// <summary>
/// Reads history events.
/// </summary>
protected override void HistoryReadEvents(
ServerSystemContext context,
ReadEventDetails details,
TimestampsToReturn timestampsToReturn,
IList<HistoryReadValueId> nodesToRead,
IList<HistoryReadResult> results,
IList<ServiceResult> errors,
List<NodeHandle> nodesToProcess,
IDictionary<NodeId, NodeState> cache)
{
for (int ii = 0; ii < nodesToProcess.Count; ii++)
{
NodeHandle handle = nodesToProcess[ii];
HistoryReadValueId nodeToRead = nodesToRead[handle.Index];
HistoryReadResult result = results[handle.Index];
HistoryReadRequest request = null;
// load an exising request.
if (nodeToRead.ContinuationPoint != null)
{
request = LoadContinuationPoint(context, nodeToRead.ContinuationPoint);
if (request == null)
{
errors[handle.Index] = StatusCodes.BadContinuationPointInvalid;
continue;
}
}
// create a new request.
else
{
request = CreateHistoryReadRequest(
context,
details,
handle,
nodeToRead);
}
// process events until the max is reached.
HistoryEvent events = new HistoryEvent();
while (request.NumValuesPerNode == 0 || events.Events.Count < request.NumValuesPerNode)
{
if (request.Events.Count == 0)
{
break;
}
BaseEventState e = null;
if (request.TimeFlowsBackward)
{
e = request.Events.Last.Value;
request.Events.RemoveLast();
}
else
{
e = request.Events.First.Value;
request.Events.RemoveFirst();
}
events.Events.Add(GetEventFields(request, e));
}
errors[handle.Index] = ServiceResult.Good;
// check if a continuation point is requred.
if (request.Events.Count > 0)
{
// only set if both end time and start time are specified.
if (details.StartTime != DateTime.MinValue && details.EndTime != DateTime.MinValue)
{
result.ContinuationPoint = SaveContinuationPoint(context, request);
}
}
// check if no data returned.
else
{
errors[handle.Index] = StatusCodes.GoodNoData;
}
// return the data.
result.HistoryData = new ExtensionObject(events);
}
}
