QuickOPC User's Guide and Reference
UnsubscribeMultipleMonitoredItems Method (EasyUAClient)
Example 



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OpcLabs.EasyOpcUA Assembly > OpcLabs.EasyOpc.UA Namespace > EasyUAClient Class : UnsubscribeMultipleMonitoredItems Method
Array of subscription handles
Unsubscribe from changes of multiple monitored items, specifying an enumerable of integer handles.
Syntax
'Declaration
 

Public Sub UnsubscribeMultipleMonitoredItems( _
   ByVal handlesToUnsubscribe As IEnumerable(Of Integer) _
)
 
'Usage
 

Dim instance As EasyUAClient
Dim handlesToUnsubscribe As IEnumerable(Of Integer)
 
instance.UnsubscribeMultipleMonitoredItems(handlesToUnsubscribe)

Parameters

handlesToUnsubscribe
Array of subscription handles
Exceptions
ExceptionDescription
System.ArgumentExceptionOne of the arguments provided to a method is not valid.
System.ArgumentNullExceptionA null reference (Nothing in Visual Basic) is passed to a method that does not accept it as a valid argument.
Remarks

 

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
// This example shows how to unsubscribe from changes of multiple items.

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

namespace UADocExamples._EasyUAClient
{
    partial class UnsubscribeMultipleMonitoredItems
    {
        public static void Main1()
        {
            UAEndpointDescriptor endpointDescriptor =
                "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
            // or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            // or "https://opcua.demo-this.com:51212/UA/SampleServer/"

            // Instantiate the client object and hook events.
            var client = new EasyUAClient();
            client.DataChangeNotification += client_DataChangeNotification;

            Console.WriteLine("Subscribing...");
            int[] handleArray = client.SubscribeMultipleMonitoredItems(new[]
                {
                    new EasyUAMonitoredItemArguments(null, endpointDescriptor, 
                        "nsu=http://test.org/UA/Data/ ;i=10845", 1000),
                    new EasyUAMonitoredItemArguments(null, endpointDescriptor, 
                        "nsu=http://test.org/UA/Data/ ;i=10853", 1000),
                    new EasyUAMonitoredItemArguments(null, endpointDescriptor, 
                        "nsu=http://test.org/UA/Data/ ;i=10855", 1000)
                });

            Console.WriteLine("Processing monitored item changed events for 10 seconds...");
            System.Threading.Thread.Sleep(10 * 1000);

            Console.WriteLine("Unsubscribing...");
            client.UnsubscribeMultipleMonitoredItems(handleArray);

            Console.WriteLine("Waiting for 5 seconds...");
            System.Threading.Thread.Sleep(5 * 1000);

            Console.WriteLine("Finished.");
        }

        static void client_DataChangeNotification(object sender, EasyUADataChangeNotificationEventArgs e)
        {
            // Display value.
            if (e.Succeeded)
                Console.WriteLine($"{e.Arguments.NodeDescriptor}: {e.AttributeData.Value}");
            else
                Console.WriteLine($"{e.Arguments.NodeDescriptor} *** Failure: {e.ErrorMessageBrief}");
        }
    }
}
// This example shows how to unsubscribe from changes of just some monitored
// items.

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

namespace UADocExamples._EasyUAClient
{
    partial class UnsubscribeMultipleMonitoredItems
    {
        public static void Some()
        {
            UAEndpointDescriptor endpointDescriptor =
                "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
            // or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            // or "https://opcua.demo-this.com:51212/UA/SampleServer/"

            // Instantiate the client object and hook events.
            var client = new EasyUAClient();
            client.DataChangeNotification += client_DataChangeNotification2;

            Console.WriteLine();
            Console.WriteLine("Subscribing...");
            int[] handleArray = client.SubscribeMultipleMonitoredItems(new[]
                {
                    new EasyUAMonitoredItemArguments(null, endpointDescriptor, 
                        "nsu=http://test.org/UA/Data/ ;i=10845", 1000),
                    new EasyUAMonitoredItemArguments(null, endpointDescriptor, 
                        "nsu=http://test.org/UA/Data/ ;i=10853", 1000),
                    new EasyUAMonitoredItemArguments(null, endpointDescriptor, 
                        "nsu=http://test.org/UA/Data/ ;i=10855", 1000)
                });

            for (int i = 0; i < handleArray.Length; i++)
                Console.WriteLine($"handleArray[{i}]: {handleArray[i]}");

            Console.WriteLine();
            Console.WriteLine("Processing monitored item changed events for 10 seconds...");
            System.Threading.Thread.Sleep(10 * 1000);

            Console.WriteLine();
            Console.WriteLine("Unsubscribing from 2 monitored items...");
            // We will unsubscribe from the first and third monitored item we have
            // previously subscribed to.
            client.UnsubscribeMultipleMonitoredItems(new [] {handleArray[0], handleArray[2]});

            Console.WriteLine();
            Console.WriteLine("Processing monitored item changed events for 10 seconds...");
            System.Threading.Thread.Sleep(10 * 1000);

            Console.WriteLine();
            Console.WriteLine("Unsubscribing from all remaining monitored items...");
            client.UnsubscribeAllMonitoredItems();

            Console.WriteLine("Waiting for 5 seconds...");
            System.Threading.Thread.Sleep(5 * 1000);

            Console.WriteLine("Finished.");
        }

        static void client_DataChangeNotification2(object sender, EasyUADataChangeNotificationEventArgs e)
        {
            // Display value.
            if (e.Succeeded)
                Console.WriteLine($"{e.Arguments.NodeDescriptor}: {e.AttributeData.Value}");
            else
                Console.WriteLine($"{e.Arguments.NodeDescriptor} *** Failure: {e.ErrorMessageBrief}");
        }
    }
}
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

See Also

Reference

EasyUAClient Class
EasyUAClient Members

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