Starting Event (IStartableEvents)

Raised when the component is starting.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
Event Starting As EventHandler

'Usage
 
Dim instance As IStartableEvents
Dim handler As EventHandler
 
AddHandler instance.Starting, handler

event EventHandler Starting

event EventHandler^ Starting

Remarks

The event handlers for this event should not throw any exceptions. If an exception is thrown from the event handler, it might be reported through debugging, tracing or logging facilities, but the processing continues as normally, i.e. the invocation of remaining handlers is not influenced.

Example

CSharp
VB.NET

// This example shows how to react to events in order to initiate and finalize data collection in the push data provision
// model.
// 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 System.Timers;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.NodeSpace;

namespace UAServerDocExamples._UAServerNode
{
    class Starting_Stopped
    {
        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 a read-only data variable.
            var dataVariable = UADataVariable.CreateIn(server.Objects, "ReadThisVariable")
                .ValueType<int>()
                .Writable(false);

            dataVariable.Starting += (sender, args) =>
            {
                // Create a timer for pushing the data for OPC reads.
                var timer = new Timer
                {
                    Interval = 1000,
                    AutoReset = true,
                };

                // Set the read attribute data of the data variable to a random value whenever the timer interval elapses.
                // Note that this example shows the basic concept, however there is also an UpdateReadAttributeData method that
                // can be used in most cases to achieve slightly more concise code.
                var random = new Random();
                timer.Elapsed += (s, a) =>
                    dataVariable.ReadAttributeData = new UAAttributeData(random.Next(), DateTime.UtcNow);
                timer.Start();

                // Associate the timer with the data variable.
                dataVariable.State = timer;
            };
            dataVariable.Stopped += (sender, args) =>
            {
                // Obtain the timer associated with the data variable.
                var timer = (Timer)((UADataVariable)sender).State;

                // Stop the timer.
                timer.Stop();
            };
            
            // 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.");
        }
    }
}

' This example shows how to react to events in order to initiate and finalize data collection in the push data provision
' model.
' 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 System.Timers
Imports OpcLabs.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.NodeSpace

Namespace _UAServerNode
    Partial Friend Class Starting_Stopped
        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 a read-only data variable.
            Dim dataVariable = UADataVariable.CreateIn(server.Objects, "ReadThisVariable") _
                .ValueType(Of Integer)() _
                .Writable(False)

            AddHandler dataVariable.Starting, Sub(sender, args)
                                                  ' Create a timer for pushing the data for OPC reads.
                                                  Dim timer = New Timer With
                                                  {
                                                    .Interval = 1000,
                                                    .AutoReset = True
                                                  }

                                                  ' Set the read attribute data of the data variable to a random value whenever the timer interval elapses.
                                                  ' Note that this example shows the basic concept, however there is also an UpdateReadAttributeData method that
                                                  ' can be used in most cases to achieve slightly more concise code.
                                                  Dim random = New Random()
                                                  AddHandler timer.Elapsed, Sub(s, a)
                                                                                dataVariable.ReadAttributeData = New UAAttributeData(random.Next(), DateTime.UtcNow)
                                                                            End Sub
                                                  timer.Start()

                                                  ' Associate the timer with the data variable.
                                                  dataVariable.State = timer
                                              End Sub

            AddHandler dataVariable.Stopped, Sub(sender, args)
                                                 ' Obtain the timer associated with the data variable.
                                                 Dim timer = CType(CType(sender, UADataVariable).State, Timer)

                                                 ' Stop the timer.
                                                 timer.Stop()
                                             End Sub

            ' 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
    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

Reference

IStartableEvents Interface
IStartableEvents Members

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Missing some example? Ask us for it on our Online Forums! You do not have to own a commercial license in order to use Online Forums, and we reply to every post.