UnsubscribeAllEvents Method (EasyAEClient)

Unsubscribe from changes of all OPC events.

Syntax

public void UnsubscribeAllEvents()

public:
void UnsubscribeAllEvents();

'Declaration
 
Public Sub UnsubscribeAllEvents()

'Usage
 
Dim instance As EasyAEClient
 
instance.UnsubscribeAllEvents()

Remarks

All event subscriptions on this IEasyAEClient object are unsubscribed. Their corresponding handles become invalid after this method is called.

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

This method operates (at least in part) asynchronously, with respect to the caller. The actual execution of the operation may be delayed, and the outcome of the operation (if any) is provided to the calling code using an event notification, callback, or other means explained in the text. In a properly written program, this method does not throw any exceptions. You should therefore not put try/catch statements or similar constructs around calls to this method. The only exceptions thrown by this method are for usage errors, i.e. when your code violates the usage contract of the method, such as passing in invalid arguments or calling the method when the state of the object does not allow it. Any operation-related errors (i.e. errors that depend on external conditions that your code cannot reliably check) are indicated by the means the operation returns its outcome (if any), which is described in the text. For more information, see Do not catch any exceptions with asynchronous or multiple-operation methods.

Example

CSharp
VB.NET

// This example shows how to unsubscribe from all event notifications.

using System;
using System.Threading;
using OpcLabs.EasyOpc.AlarmsAndEvents;
using OpcLabs.EasyOpc.AlarmsAndEvents.OperationModel;

namespace DocExamples.AlarmsAndEvents._EasyAEClient
{
    class UnsubscribeAllEvents
    {
        public static void Main1()
        {
            // Instantiate the client object.
            using (var client = new EasyAEClient())
            {
                var eventHandler = new EasyAENotificationEventHandler(client_Notification);
                client.Notification += eventHandler;

                Console.WriteLine("Subscribing...");
                client.SubscribeEvents("", "OPCLabs.KitEventServer.2", 1000);

                Console.WriteLine("Waiting for 10 seconds...");
                Thread.Sleep(10 * 1000);

                Console.WriteLine("Unsubscribing...");
                client.UnsubscribeAllEvents();

                Console.WriteLine("Waiting for 10 seconds...");
                Thread.Sleep(10 * 1000);
            }
        }

        // Notification event handler
        static void client_Notification(object sender, EasyAENotificationEventArgs e)
        {
            if (!e.Succeeded)
            {
                Console.WriteLine("*** Failure: {0}", e.ErrorMessageBrief);
                return;
            }
            if (!(e.EventData is null))
                Console.WriteLine(e.EventData.Message);
        }
    }
}

' This example shows how to unsubscribe from all event notifications.

Imports System.Threading
Imports OpcLabs.EasyOpc.AlarmsAndEvents
Imports OpcLabs.EasyOpc.AlarmsAndEvents.OperationModel

Namespace AlarmsAndEvents._EasyAEClient

    Friend Class UnsubscribeAllEvents
        Public Shared Sub Main1()
            Using client = New EasyAEClient()
                Dim eventHandler = New EasyAENotificationEventHandler(AddressOf client_Notification)
                AddHandler client.Notification, eventHandler

                Console.WriteLine("Subscribing...")
                client.SubscribeEvents("", "OPCLabs.KitEventServer.2", 1000)

                Console.WriteLine("Waiting for 10 seconds...")
                Thread.Sleep(10 * 1000)

                Console.WriteLine("Unsubscribing...")
                client.UnsubscribeAllEvents()

                Console.WriteLine("Waiting for 10 seconds...")
                Thread.Sleep(10 * 1000)
            End Using
        End Sub

        ' Notification event handler
        Private Shared Sub client_Notification(ByVal sender As Object, ByVal e As EasyAENotificationEventArgs)
            If Not e.Succeeded Then
                Console.WriteLine("*** Failure: {0}", e.ErrorMessageBrief)
                Exit Sub
            End If
            If e.EventData IsNot Nothing Then
                Console.WriteLine(e.EventData.Message)
            End If
        End Sub
    End Class
End Namespace

Requirements

Target Platforms: .NET Framework: Windows 10 (selected versions), Windows 11 (selected versions), Windows Server 2012 R2, Windows Server 2016; .NET: Linux, macOS, Microsoft Windows

Reference

EasyAEClient Class
EasyAEClient Members

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