/// <summary>
/// Returns the history data source for a node.
/// </summary>
protected virtual ServiceResult GetHistoryDataSource(
Opc.Ua.Server.ServerSystemContext context,
BaseVariableState variable,
out IHistoryDataSource datasource)
{
datasource = m_system.GetHistoryFile(variable);
if (datasource == null)
{
return(StatusCodes.BadNotReadable);
}
return(ServiceResult.Good);
}
/// <summary>
/// Constructs a reader for the source.
/// </summary>
/// <param name="source">The source of the history data.</param>
public HistoryDataReader(NodeId variableId, IHistoryDataSource source)
{
m_id = Guid.NewGuid();
m_variableId = variableId;
m_source = source;
}
/// <summary>
/// Reads the raw data for a variable
/// </summary>
protected ServiceResult HistoryReadRaw(
ISystemContext context,
BaseVariableState source,
ReadRawModifiedDetails details,
TimestampsToReturn timestampsToReturn,
bool releaseContinuationPoints,
HistoryReadValueId nodeToRead,
HistoryReadResult result)
{
ServerSystemContext serverContext = context as ServerSystemContext;
HistoryDataReader reader = null;
HistoryData data = new HistoryData();
if (nodeToRead.ContinuationPoint != null && nodeToRead.ContinuationPoint.Length > 0)
{
// restore the continuation point.
reader = RestoreDataReader(serverContext, nodeToRead.ContinuationPoint);
if (reader == null)
{
return(StatusCodes.BadContinuationPointInvalid);
}
// node id must match previous node id.
if (reader.VariableId != nodeToRead.NodeId)
{
Utils.SilentDispose(reader);
return(StatusCodes.BadContinuationPointInvalid);
}
// check if releasing continuation points.
if (releaseContinuationPoints)
{
Utils.SilentDispose(reader);
return(ServiceResult.Good);
}
}
else
{
// get the source for the variable.
IHistoryDataSource datasource = null;
ServiceResult error = GetHistoryDataSource(serverContext, source, out datasource);
if (ServiceResult.IsBad(error))
{
return(error);
}
// create a reader.
reader = new HistoryDataReader(nodeToRead.NodeId, datasource);
// start reading.
reader.BeginReadRaw(
serverContext,
details,
timestampsToReturn,
nodeToRead.ParsedIndexRange,
nodeToRead.DataEncoding,
data.DataValues);
}
// continue reading data until done or max values reached.
bool complete = reader.NextReadRaw(
serverContext,
timestampsToReturn,
nodeToRead.ParsedIndexRange,
nodeToRead.DataEncoding,
data.DataValues);
// save continuation point.
if (!complete)
{
SaveDataReader(serverContext, reader);
result.StatusCode = StatusCodes.GoodMoreData;
}
// return the dat.
result.HistoryData = new ExtensionObject(data);
return(result.StatusCode);
}
/// <summary>
/// Returns the history data source for a node.
/// </summary>
protected virtual ServiceResult GetHistoryDataSource(
Opc.Ua.Server.ServerSystemContext context,
BaseVariableState variable,
out IHistoryDataSource datasource)
{
datasource = m_system.GetHistoryFile(variable);
if (datasource == null)
{
return StatusCodes.BadNotReadable;
}
return ServiceResult.Good;
}
/// <summary>
/// Constructs a reader for the source.
/// </summary>
/// <param name="source">The source of the history data.</param>
public HistoryDataReader(NodeId variableId, IHistoryDataSource source)
{
m_id = Guid.NewGuid();
m_variableId = variableId;
m_source = source;
}
