UnlockConnection Method (_EasyUAClientConnectionControl)

Unlocks a connection.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
Sub UnlockConnection( _
   ByVal lockHandle As Integer _
)

'Usage
 
Dim instance As _EasyUAClientConnectionControl
Dim lockHandle As Integer
 
instance.UnlockConnection(lockHandle)

void UnlockConnection( 
   int lockHandle
)

void UnlockConnection( 
   int lockHandle
)

Parameters

lockHandle: The connection lock handle, returned by the LockConnection call.

Exceptions

Exception	Description
System.ArgumentException	One of the arguments provided to a method is not valid. This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.

Exception

Description

System.ArgumentException

One of the arguments provided to a method is not valid.

This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.

Example

.NET

// This example shows how to lock and unlock connections to an OPC UA server. The component attempts to keep the locked
// connections open, until unlocked.

using System;
using Microsoft.Extensions.DependencyInjection;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.OperationModel;
using OpcLabs.EasyOpc.UA.Services;

namespace UADocExamples._EasyUAClientConnectionControl
{
    class LockAndUnlockConnection
    {
        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
            using (var client = new EasyUAClient())
            {
                // Obtain the client connection monitoring service.
                IEasyUAClientConnectionMonitoring clientConnectionMonitoring = client.GetService<IEasyUAClientConnectionMonitoring>();
                if (clientConnectionMonitoring is null)
                {
                    Console.WriteLine("The client connection monitoring service is not available.");
                    return;
                }

                // Obtain the client connection control service.
                IEasyUAClientConnectionControl clientConnectionControl = client.GetService<IEasyUAClientConnectionControl>();
                if (clientConnectionControl is null)
                {
                    Console.WriteLine("The client connection control service is not available.");
                    return;
                }

                // Display the server condition changed events.
                clientConnectionMonitoring.ServerConditionChanged += (sender, args) => Console.WriteLine(args);

                int lockHandle = 0;
                bool locked = false;
                try
                {
                    Console.WriteLine("Reading (1)");
                    // The first read will cause a connection to the server.
                    UAAttributeData attributeData1 =
                        client.Read(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10853");
                    Console.WriteLine(attributeData1);

                    Console.WriteLine("Waiting for 10 seconds...");
                    // Since the connection is now not used for some time, and it is not locked, it will be closed.
                    System.Threading.Thread.Sleep(10 * 1000);

                    Console.WriteLine("Locking");
                    // Locking the connection causes it to open, if possible.
                    lockHandle = clientConnectionControl.LockConnection(endpointDescriptor);
                    locked = true;

                    Console.WriteLine("Waiting for 10 seconds...");
                    // The connection is locked, it will not be closed now.
                    System.Threading.Thread.Sleep(10 * 1000);

                    Console.WriteLine("Reading (2)");
                    UAAttributeData attributeData2 =
                        client.Read(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10853");
                    Console.WriteLine(attributeData2);

                    Console.WriteLine("Waiting for 10 seconds...");
                    // The connection is still locked, it will not be closed now.
                    System.Threading.Thread.Sleep(10 * 1000);
                }
                catch (UAException uaException)
                {
                    Console.WriteLine("*** Failure: {0}", uaException.GetBaseException().Message);
                }
                finally
                {
                    if (locked)
                    {
                        Console.WriteLine("Unlocking");
                        clientConnectionControl.UnlockConnection(lockHandle);
                    }
                }

                Console.WriteLine("Waiting for 10 seconds...");
                // After some delay, the connection will be closed, because there are no subscriptions to the server and no
                // connection locks.
                System.Threading.Thread.Sleep(10 * 1000);

                Console.WriteLine("Finished.");
            }
        }


        // Example output:
        //
        //Reading (1)
        //"opc.tcp://opcua.demo-this.com:51210/UA/SampleServer" Connecting; Success; Attempt #1
        //"opc.tcp://opcua.demo-this.com:51210/UA/SampleServer" Connected; Success
        //-1.034588E+18 {Single} @2021-11-15T15:26:39.169 @@2021-11-15T15:26:39.169; Good
        //Waiting for 10 seconds...
        //"opc.tcp://opcua.demo-this.com:51210/UA/SampleServer" Disconnecting; Success
        //"opc.tcp://opcua.demo-this.com:51210/UA/SampleServer" Disconnected(RetrialDelay=Infinite); Success
        //Locking
        //"opc.tcp://opcua.demo-this.com:51210/UA/SampleServer" Connecting; Success; Attempt #1
        //"opc.tcp://opcua.demo-this.com:51210/UA/SampleServer" Connected; Success
        //Waiting for 10 seconds...
        //Reading (2)
        //2.288872E+21 {Single} @2021-11-15T15:26:59.836 @@2021-11-15T15:26:59.836; Good
        //Waiting for 10 seconds...
        //Unlocking
        //Waiting for 10 seconds...
        //"opc.tcp://opcua.demo-this.com:51210/UA/SampleServer" Disconnecting; Success
        //"opc.tcp://opcua.demo-this.com:51210/UA/SampleServer" Disconnected(RetrialDelay=Infinite); Success
        //Finished.
    }
}

# This example shows how to lock and unlock connections to an OPC UA server. The component attempts to keep the locked
# connections open, until unlocked.
import time

# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc

# Import .NET namespaces.
from Microsoft.Extensions.DependencyInjection import *
from OpcLabs.EasyOpc.UA import *
from OpcLabs.EasyOpc.UA.OperationModel import *
from OpcLabs.EasyOpc.UA.Services import *


endpointDescriptor = UAEndpointDescriptor('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.
client = None
try:
    client = EasyUAClient()

    # Obtain the client connection monitoring service.
    clientConnectionMonitoring = ServiceProviderServiceExtensions.GetService[IEasyUAClientConnectionMonitoring](client)
    if clientConnectionMonitoring is None:
        print('The client connection monitoring service is not available.')
        exit()

    # Obtain the client connection control service.
    clientConnectionControl = ServiceProviderServiceExtensions.GetService[IEasyUAClientConnectionControl](client)
    if clientConnectionControl is None:
        print('The client connection control service is not available.')
        exit()

    # Display the server condition changed events.
    clientConnectionMonitoring.ServerConditionChanged += lambda sender, args: print(args)

    lockHandle = 0
    locked = False
    try:
        print('Reading (1)')
        # The first read will cause a connection to the server.
        attributeData1 = IEasyUAClientExtension.Read(client,
                                                     endpointDescriptor,
                                                     UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10853'))
        print(attributeData1)

        print('Waiting for 10 seconds...')
        # Since the connection is now not used for some time, and it is not locked, it will be closed.
        time.sleep(10)

        print('Locking')
        # Locking the connection causes it to open, if possible.
        lockHandle = clientConnectionControl.LockConnection(endpointDescriptor)
        locked = True

        print('Waiting for 10 seconds...')
        # The connection is locked, it will not be closed now.
        time.sleep(10)

        print('Reading (2)')
        attributeData2 = IEasyUAClientExtension.Read(client,
                                                     endpointDescriptor,
                                                     UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10853'))
        print(attributeData2)

        print('Waiting for 10 seconds...')
        # The connection is still locked, it will not be closed now.
        time.sleep(10)

    except UAException as uaException:
        print('*** Failure: ' + uaException.GetBaseException().Message)

    finally:
        if locked:
            print('Unlocking')
            clientConnectionControl.UnlockConnection(lockHandle)

    print('Waiting for 10 seconds...')
    # After some delay, the connection will be closed, because there are no subscriptions to the server and no
    # connection locks.
    time.sleep(10)

    print('Finished.')

finally:
    client and client.Dispose()

VBScript

Rem This example shows how to lock and unlock connections to an OPC UA server. The component attempts to keep the locked
Rem connections open, until unlocked.

Option Explicit

Dim endpointDescriptorUrlString: endpointDescriptorUrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
Dim EndpointDescriptor: Set EndpointDescriptor = CreateObject("OpcLabs.EasyOpc.UA.UAEndpointDescriptor")
EndpointDescriptor.UrlString = endpointDescriptorUrlString

' Instantiate the client object.
Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.UA.EasyUAClient")

' Obtain the client connection monitoring service.
Dim ClientConnectionMonitoring: Set ClientConnectionMonitoring = Client.GetServiceByName("OpcLabs.EasyOpc.UA.Services.IEasyUAClientConnectionMonitoring, OpcLabs.EasyOpcUA")
If ClientConnectionMonitoring Is Nothing Then
    WScript.Echo "The client connection monitoring service is not available."
    WScript.Quit
End If

' Obtain the client connection control service.
Dim ClientConnectionControl: Set ClientConnectionControl = Client.GetServiceByName("OpcLabs.EasyOpc.UA.Services.IEasyUAClientConnectionControl, OpcLabs.EasyOpcUA")
If ClientConnectionControl Is Nothing Then
    WScript.Echo "The client connection control service is not available."
    WScript.Quit
End If

' Display the server condition changed events.
WScript.ConnectObject ClientConnectionMonitoring, "ClientConnectionMonitoring_"

WScript.Echo "Reading (1)"
' The first read will cause a connection to the server.
Dim AttributeData1: Set AttributeData1 = Client.Read(endpointDescriptorUrlString, "nsu=http://test.org/UA/Data/ ;i=10853")
WScript.Echo AttributeData1

WScript.Echo "Waiting for 10 seconds..."
' Since the connection is now not used for some time, and it is not locked, it will be closed.
WScript.Sleep 10*1000

WScript.Echo "Locking..."
' Locking the connection causes it to open, if possible.
Dim lockHandle: lockHandle = ClientConnectionControl.LockConnection(EndpointDescriptor)

WScript.Echo "Waiting for 10 seconds..."
' The connection is locked, it will not be closed now.
WScript.Sleep 10*1000

WScript.Echo "Reading (2)"
' The second read, because it closely follows the first one, will reuse the connection that is already open.
Dim AttributeData2: Set AttributeData2 = Client.Read(endpointDescriptorUrlString, "nsu=http://test.org/UA/Data/ ;i=10853")
WScript.Echo AttributeData2

WScript.Echo "Waiting for 10 seconds..."
' The connection is still locked, it will not be closed now.
WScript.Sleep 10*1000

WScript.Echo "Unlocking..."
ClientConnectionControl.UnlockConnection(lockHandle)

WScript.Echo "Waiting for 10 seconds..."
' After some delay, the connection will be closed, because there are no subscriptions to the server and no
' connection locks.
WScript.Sleep 10*1000

WScript.Echo "Finished."



Sub ClientConnectionMonitoring_ServerConditionChanged(Sender, e)
    WScript.Echo e
End Sub


' Example output:
'
'Reading (1)
'"opc.tcp://opcua.demo-this.com:51210/UA/SampleServer" Connecting; Success; Attempt #1
'"opc.tcp://opcua.demo-this.com:51210/UA/SampleServer" Connected; Success
'-1.034588E+18 {Single} @2021-11-15T15:26:39.169 @@2021-11-15T15:26:39.169; Good
'Waiting for 10 seconds...
'"opc.tcp://opcua.demo-this.com:51210/UA/SampleServer" Disconnecting; Success
'"opc.tcp://opcua.demo-this.com:51210/UA/SampleServer" Disconnected(RetrialDelay=Infinite); Success
'Locking
'"opc.tcp://opcua.demo-this.com:51210/UA/SampleServer" Connecting; Success; Attempt #1
'"opc.tcp://opcua.demo-this.com:51210/UA/SampleServer" Connected; Success
'Waiting for 10 seconds...
'Reading (2)
'2.288872E+21 {Single} @2021-11-15T15:26:59.836 @@2021-11-15T15:26:59.836; Good
'Waiting for 10 seconds...
'Unlocking
'Waiting for 10 seconds...
'"opc.tcp://opcua.demo-this.com:51210/UA/SampleServer" Disconnecting; Success
'"opc.tcp://opcua.demo-this.com:51210/UA/SampleServer" Disconnected(RetrialDelay=Infinite); Success
'Finished.

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

_EasyUAClientConnectionControl Interface
_EasyUAClientConnectionControl Members

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