OPC Studio User's Guide and Reference
ParentNode Property (UAServerNode)
Example 



OpcLabs.ServerOpcUA Assembly > OpcLabs.EasyOpc.UA.NodeSpace Namespace > UAServerNode Class : ParentNode Property
The server node that is the parent of this node.
Syntax
'Declaration
 
<BrowsableAttribute(False)>
<CanBeNullAttribute()>
<IgnoreDataMemberAttribute()>
Public Shadows ReadOnly Property ParentNode As UAServerNode
'Usage
 
Dim instance As UAServerNode
Dim value As UAServerNode
 
value = instance.ParentNode
[Browsable(false)]
[CanBeNull()]
[IgnoreDataMember()]
public new UAServerNode ParentNode {get;}
[Browsable(false)]
[CanBeNull()]
[IgnoreDataMember()]
public:
new property UAServerNode^ ParentNode {
   UAServerNode^ get();
}

Property Value

This value of this property can be null (Nothing in Visual Basic).

Remarks

This property is null when this node has no parent.

This method or property does not throw any exceptions, aside from execution exceptions such as System.Threading.ThreadAbortException or System.OutOfMemoryException.

Example
// This example shows how data from parent node can be used in the read event handler.
// You can use any OPC UA client, including our Connectivity Explorer and OpcCmd utility, to connect to the server. 
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client, server and subscriber examples in C# on GitHub: https://github.com/OPCLabs/Examples-OPCStudio-CSharp .
// Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
// a commercial license in order to use Online Forums, and we reply to every post.

using System;
using OpcLabs.BaseLib.NodeSpace;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.NodeSpace;
using OpcLabs.EasyOpc.UA.OperationModel;

namespace UAServerDocExamples._UAServerNode
{
    class ParentNode
    {
        public static void Main1()
        {
            // Instantiate the server object.
            // By default, the server will run on endpoint URL "opc.tcp://localhost:48040/".
            var server = new EasyUAServer();

            // Create multiple folder nodes, each with a data variable in it. Distinguish the folders by their state, however
            // the data variables are constructed the same, and use the same read event handler.

            UAFolder myFolder1 = UAFolder.CreateIn(server.Objects, "MyFolder1").SetState(1);
            UADataVariable.CreateIn(myFolder1, "MyDataVariable").Read += MyDataVariableOnRead;

            UAFolder myFolder2 = UAFolder.CreateIn(server.Objects, "MyFolder2").SetState(2);
            UADataVariable.CreateIn(myFolder2, "MyDataVariable").Read += MyDataVariableOnRead;

            UAFolder myFolder3 = UAFolder.CreateIn(server.Objects, "MyFolder3").SetState(3);
            UADataVariable.CreateIn(myFolder3, "MyDataVariable").Read += MyDataVariableOnRead;

            UAFolder myFolder4 = UAFolder.CreateIn(server.Objects, "MyFolder4").SetState(4);
            UADataVariable.CreateIn(myFolder4, "MyDataVariable").Read += MyDataVariableOnRead;

            UAFolder myFolder5 = UAFolder.CreateIn(server.Objects, "MyFolder5").SetState(5);
            UADataVariable.CreateIn(myFolder5, "MyDataVariable").Read += MyDataVariableOnRead;

            // Start the server.
            Console.WriteLine("The server is starting...");
            server.Start();

            Console.WriteLine("The server is started.");
            Console.WriteLine();

            // Let the user decide when to stop.
            Console.WriteLine("Press Enter to stop the server...");
            Console.ReadLine();

            // Stop the server.
            Console.WriteLine("The server is stopping...");
            server.Stop();

            Console.WriteLine("The server is stopped.");
        }

        /// <summary>
        /// Event handler for the read event on the data variable. 
        /// </summary>
        /// <param name="sender">The data variable object that sends the event.</param>
        /// <param name="e">Data for the variable read event.</param>
        static private void MyDataVariableOnRead(object sender, UADataVariableReadEventArgs e)
        {
            // Obtain the parent folder of the data variable that is being read.
            UAServerNode parentNode = e.DataVariable.ParentNode;

            // Obtain the state associated with the folder, where the data variable is located.
            // Use it as the offset for the random value, so that each data variable generates values in a unique range.
            int offset = (int)parentNode.State*100;

            // Generate a random value, indicate that the read has been handled, and return the generated value.
            e.HandleAndReturn(Random.Next(offset, offset + 100));
        }

        static private readonly Random Random = new Random();
    }
}
' This example shows how data from parent node can be used in the read event handler.
' You can use any OPC UA client, including our Connectivity Explorer and OpcCmd utility, to connect to the server. 
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
' OPC client and subscriber examples in VB.NET on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VBNET .
' Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
' a commercial license in order to use Online Forums, and we reply to every post.

Imports System
Imports OpcLabs.BaseLib.NodeSpace
Imports OpcLabs.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.NodeSpace
Imports OpcLabs.EasyOpc.UA.OperationModel

Namespace _UAServerNode
    Partial Friend Class ParentNode
        Shared Sub Main1()
            ' Instantiate the server object.
            ' By default, the server will run on endpoint URL "opc.tcp://localhost:48040/".
            Dim server = New EasyUAServer()

            ' Create multiple folder nodes, each with a data variable in it. Distinguish the folders by their state, however
            ' the data variables are constructed the same, and use the same read event handler.

            Dim myFolder1 As UAFolder = UAFolder.CreateIn(server.Objects, "MyFolder1").SetState(1)
            AddHandler UADataVariable.CreateIn(myFolder1, "MyDataVariable").Read, AddressOf MyDataVariableOnRead

            Dim myFolder2 As UAFolder = UAFolder.CreateIn(server.Objects, "MyFolder2").SetState(2)
            AddHandler UADataVariable.CreateIn(myFolder2, "MyDataVariable").Read, AddressOf MyDataVariableOnRead

            Dim myFolder3 As UAFolder = UAFolder.CreateIn(server.Objects, "MyFolder3").SetState(3)
            AddHandler UADataVariable.CreateIn(myFolder3, "MyDataVariable").Read, AddressOf MyDataVariableOnRead

            Dim myFolder4 As UAFolder = UAFolder.CreateIn(server.Objects, "MyFolder4").SetState(4)
            AddHandler UADataVariable.CreateIn(myFolder4, "MyDataVariable").Read, AddressOf MyDataVariableOnRead

            Dim myFolder5 As UAFolder = UAFolder.CreateIn(server.Objects, "MyFolder5").SetState(5)
            AddHandler UADataVariable.CreateIn(myFolder5, "MyDataVariable").Read, AddressOf MyDataVariableOnRead

            ' Start the server.
            Console.WriteLine("The server is starting...")
            server.Start()

            Console.WriteLine("The server is started.")
            Console.WriteLine()

            ' Let the user decide when to stop.
            Console.WriteLine("Press Enter to stop the server...")
            Console.ReadLine()

            ' Stop the server.
            Console.WriteLine("The server is stopping...")
            server.Stop()

            Console.WriteLine("The server is stopped.")
        End Sub

        ''' <summary>
        ''' Event handler for the read event on the data variable. 
        ''' </summary>
        ''' <param name="sender">The data variable object that sends the event.</param>
        ''' <param name="e">Data for the variable read event.</param>
        Private Shared Sub MyDataVariableOnRead(ByVal sender As Object, ByVal e As UADataVariableReadEventArgs)
            ' Obtain the parent folder of the data variable that is being read.
            Dim parentNode As UAServerNode = e.DataVariable.ParentNode

            ' Obtain the state associated with the folder, where the data variable is located.
            ' Use it as the offset for the random value, so that each data variable generates values in a unique range.
            Dim offset As Integer = CInt(parentNode.State * 100)

            ' Generate a random value, indicate that the read has been handled, and return the generated value.
            e.HandleAndReturn(Random.Next(offset, offset + 100))
        End Sub

        Private Shared ReadOnly Random As Random = New Random()
    End Class
End Namespace
Requirements

Target Platforms: .NET Framework: Windows 10 (selected versions), Windows 11 (selected versions), Windows Server 2016, Windows Server 2022; .NET: Linux, macOS, Microsoft Windows

See Also