/// <summary>
/// Creates the nodes provided and associated with the node manager.
/// </summary>
/// <param name="references">A dictionary used to determine the logical references between
/// existing nodes (e.g. OPC default nodes) and the nodes provided by the node
/// manager.</param>
/// <returns>An enumerable containing the root nodes of the node manager.</returns>
/// <remarks>This method will be only called once by the server on start up.</remarks>
protected override IEnumerable <IOpcNode> CreateNodes(OpcNodeReferenceCollection references)
{
// It is necessary to assign to all root nodes one of the namespaces used to
// identify one of the associated namespaces (see the ctor of the class). This
// namespace does identify the node as member of the namespace of the node
// manager. Optionally it is possible to assign namespace to the child nodes
// too. But by default their missing namespace will be auto-completed through the
// namespace of their parent node.
var machineOne = new OpcFolderNode(this.DefaultNamespace.GetName("Machine_1"));
// Add new reference to make the node visible beneath the ObjectsFolder
// (the top most root node within every OPC UA server).
references.Add(machineOne, OpcObjectTypes.ObjectsFolder);
new OpcDataVariableNode <string>(machineOne, "Name", "Machine 1");
new OpcDataVariableNode <byte>(machineOne, "Status", 1);
this.positionHistorian = new OpcNodeHistorian(
this, new OpcDataVariableNode <int>(machineOne, "Position", -1));
SampleNodeManager.CreateHistoryEntries(this.positionHistorian);
new OpcDataVariableNode <bool>(machineOne, "IsActive", true);
new OpcDataVariableNode <double>(machineOne, "Temperature", 18.3);
return(new IOpcNode[] { machineOne });
}
/// <summary>
/// Creates the different entries contained in the raw history and modified raw history
/// of the node historian used.
/// </summary>
/// <param name="historian">The <see cref="OpcNodeHistorian"/> its history
/// entries being created.</param>
private static void CreateHistoryEntries(OpcNodeHistorian historian)
{
for (int second = 0; second < 3600; second++)
{
var value = new OpcHistoryValue(
1000 + second, DateTime.UtcNow.Date.AddHours(6).AddSeconds(second));
if ((second % 30) == 0)
{
historian.ModifiedHistory.Add(value.CreateModified(
OpcHistoryModificationType.Delete, "Anonymous", value.Timestamp));
}
else
{
historian.History.Add(value);
}
}
}
protected override void AddNode(
OpcContext context,
IOpcNode node,
IEnumerable <IOpcNodeReferenceAware> references)
{
base.AddNode(context, node, references);
// "Catch" nodes added by the client and "attach" the on-demand timestamp determination
// (see HandleWriteVariableValue) and a simple in-memory historian which shall
// automatically fill its historical values whenever a node value is written.
if (node is OpcVariableNode variableNode && variableNode.AccessLevel.HasFlag(OpcAccessLevel.HistoryRead))
{
variableNode.WriteVariableValueCallback = this.HandleWriteVariableValue;
variableNode.IsHistorizing = true;
var historian = new OpcNodeHistorian(this, variableNode);
historian.AutoUpdateHistory = true;
this.historians.Add(node, historian);
}
}
