QuickOPC User's Guide and Reference
GetConnectionElement Method (_UAReadOnlyPubSubConfiguration)
Example 



OpcLabs.EasyOpcUA Assembly > OpcLabs.EasyOpc.UA.PubSub.Configuration.ComTypes Namespace > _UAReadOnlyPubSubConfiguration Interface : GetConnectionElement Method
The name of the PubSub connection.
Gets the element for the PubSub connection with specified name.
Syntax
'Declaration
 
<NotNullAttribute()>
Function GetConnectionElement( _
   ByVal pubSubConnectionName As String _
) As UAPubSubConnectionElement
'Usage
 
Dim instance As _UAReadOnlyPubSubConfiguration
Dim pubSubConnectionName As String
Dim value As UAPubSubConnectionElement
 
value = instance.GetConnectionElement(pubSubConnectionName)
[NotNull()]
UAPubSubConnectionElement GetConnectionElement( 
   string pubSubConnectionName
)
[NotNull()]
UAPubSubConnectionElement^ GetConnectionElement( 
   String^ pubSubConnectionName
) 

Parameters

pubSubConnectionName
The name of the PubSub connection.

Return Value

Returns the PubSub connection element.
Exceptions
ExceptionDescription

A null reference (Nothing in Visual Basic) is passed to a method that does not accept it as a valid argument.

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.

The OPC UA operation has failed. This operation exception in uniformly used to allow common handling of various kinds of errors. The System.Exception.InnerException always contains information about the actual error cause.

This is an operation error that depends on factors external to your program, and thus cannot be always avoided. Your code must handle it appropriately.

There is a logical error in the OPC UA operation.

This is an operation error that depends on factors external to your program, and thus cannot be always avoided. Your code must handle it appropriately.

Example

.NET

COM

// This example obtains and prints out information about PubSub connections, writer groups, and dataset writers in the
// OPC UA PubSub configuration.

using System;
using OpcLabs.BaseLib.Collections.Specialized;
using OpcLabs.EasyOpc.UA.OperationModel;
using OpcLabs.EasyOpc.UA.PubSub.Configuration;
using OpcLabs.EasyOpc.UA.PubSub.InformationModel;
using OpcLabs.EasyOpc.UA.PubSub.InformationModel.Extensions;

namespace UADocExamples.PubSub._IUAReadOnlyPubSubConfiguration
{
    partial class GetMethods
    {
        public static void PubSubComponents()
        {
            // Instantiate the publish-subscribe client object.
            var publishSubscribeClient = new EasyUAPublishSubscribeClient();

            try
            {
                Console.WriteLine("Loading the configuration...");
                // Load the PubSub configuration from a file. The file itself is at the root of the project, and we have
                // specified that it has to be copied to the project's output directory.
                IUAReadOnlyPubSubConfiguration pubSubConfiguration =
                    publishSubscribeClient.LoadReadOnlyConfiguration("UADemoPublisher-Default.uabinary");

                // Alternatively, using the statement below, you can access a live configuration residing in an OPC UA Server
                // with appropriate information model.
                //IUAReadOnlyPubSubConfiguration pubSubConfiguration =
                //    publishSubscribeClient.AccessReadOnlyConfiguration("opc.tcp://localhost:48010");

                // Get the names of PubSub connections in the configuration, regardless of the folder they reside in.
                StringCollection pubSubConnectionNames = pubSubConfiguration.ListConnectionNames();
                foreach (string pubSubConnectionName in pubSubConnectionNames)
                {
                    Console.WriteLine($"PubSub connection: {pubSubConnectionName}");

                    // You can use the statement below to obtain parameters of the PubSub connection.
                    //UAPubSubConnectionElement connectionElement = 
                    //    pubSubConfiguration.GetConnectionElement(pubSubConnectionName);

                    // Get names of the writer groups on this PubSub connection.
                    StringCollection writerGroupNames = pubSubConfiguration.ListWriterGroupNames(pubSubConnectionName);
                    foreach (string writerGroupName in writerGroupNames)
                    {
                        Console.WriteLine($"  Writer group: {writerGroupName}");

                        // You can use the statement below to obtain parameters of the writer group.
                        //UAWriterGroupElement writerGroupElement = 
                        //    pubSubConfiguration.GetWriterGroupElement(pubSubConnectionName, writerGroupName);

                        // Get names of the dataset writers on this writer group.
                        StringCollection dataSetWriterNames =
                            pubSubConfiguration.ListDataSetWriterNames(pubSubConnectionName, writerGroupName);
                        foreach (string dataSetWriterName in dataSetWriterNames)
                        {
                            Console.WriteLine($"    Dataset writer: {dataSetWriterName}");

                            // You can use the statement below to obtain parameters of the dataset writer.
                            //UADataSetWriterElement dataSetWriterElement = pubSubConfiguration.GetDataSetWriterElement(
                            //    pubSubConnectionName, writerGroupName, dataSetWriterName);
                        }
                    }
                }
            }
            catch (UAException uaException)
            {
                Console.WriteLine($"*** Failure: {uaException.InnerException.Message}");
            }

            Console.WriteLine("Finished.");
        }

        // Example output:
        //
        //Loading the configuration...
        //PubSub connection: FixedLayoutConnection
        //  Writer group: FixedLayoutGroup
        //    Dataset writer: SimpleWriter
        //    Dataset writer: AllTypesWriter
        //    Dataset writer: MassTestWriter
        //PubSub connection: DynamicLayoutConnection
        //  Writer group: DynamicLayoutGroup
        //    Dataset writer: SimpleWriter
        //    Dataset writer: MassTestWriter
        //    Dataset writer: AllTypes-DynamicWriter
        //    Dataset writer: EventSimpleWriter
        //PubSub connection: FlexibleLayoutConnection
        //  Writer group: FlexibleLayoutGroup
        //    Dataset writer: SimpleWriter
        //    Dataset writer: MassTestWriter
        //    Dataset writer: AllTypes-DynamicWriter
        //Finished.
    }
}
# This example obtains and prints out information about PubSub connections, writer groups, and dataset writers in the
# OPC UA PubSub configuration.

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

# Import .NET namespaces.
from OpcLabs.BaseLib import *
#from OpcLabs.EasyOpc.UA import *
#from OpcLabs.EasyOpc.UA.PubSub.Configuration.Extensions import *
from OpcLabs.EasyOpc.UA.OperationModel import *
from OpcLabs.EasyOpc.UA.PubSub.InformationModel import *
from OpcLabs.EasyOpc.UA.PubSub.InformationModel.Extensions import *
from OpcLabs.EasyOpc.UA.PubSub.OperationModel import *


# Instantiate the publish-subscribe client object.
publishSubscribeClient = EasyUAPublishSubscribeClient()

try:
    print('Loading the configuration...')
    # Load the PubSub configuration from a file. The file itself is in this script's directory.
    pubSubConfiguration = IEasyUAPublishSubscribeClientExtension.LoadReadOnlyConfiguration(publishSubscribeClient,
        'UADemoPublisher-Default.uabinary')

    # Alternatively, using the statement below, you can access a live configuration residing in an OPC UA
    # Server with appropriate information model.
    #pubSubConfiguration = publishSubscribeClient.AccessReadOnlyConfiguration(
    #    UAEndpointDescriptor('opc.tcp://localhost:48010'))

    # Get the names of PubSub connections in the configuration, regardless of the folder they reside in.
    pubSubConnectionNames = pubSubConfiguration.ListConnectionNames()
    for pubSubConnectionName in pubSubConnectionNames:
        print('PubSub connection: ', pubSubConnectionName, sep='')

        # You can use the statement below to obtain parameters of the PubSub connection.
        #connectionElement = IUAReadOnlyPubSubConfigurationExtension.GetConnectionElement(pubSubConfiguration,
        #    pubSubConnectionName)

        # Get names of the writer groups on this PubSub connection.
        writerGroupNames = pubSubConfiguration.ListWriterGroupNames(pubSubConnectionName)
        for writerGroupName in writerGroupNames:
            print('  Writer group: ', writerGroupName, sep='')

            # You can use the statement below to obtain parameters of the writer group.
            #writerGroupElement = IUAReadOnlyPubSubConfigurationExtension.GetWriterGroupElement(pubSubConfiguration,
            #    pubSubConnectionName, writerGroupName)

            # Get names of the dataset writers on this writer group.
            dataSetWriterNames = pubSubConfiguration.ListDataSetWriterNames(pubSubConnectionName, writerGroupName)
            for dataSetWriterName in dataSetWriterNames:
                print('    Dataset writer: ', dataSetWriterName, sep='')

                # You can use the statement below to obtain parameters of the dataset writer.
                #dataSetWriterElement = IUAReadOnlyPubSubConfigurationExtension.GetDataSetWriterElement(pubSubConfiguration,
                #    pubSubConnectionName, writerGroupName, dataSetWriterName)

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

print('Finished.')
' This example obtains and prints out information about PubSub connections, writer groups, and dataset writers in the
' OPC UA PubSub configuration.

Imports OpcLabs.EasyOpc.UA.OperationModel
Imports OpcLabs.EasyOpc.UA.PubSub.Configuration
'Imports OpcLabs.EasyOpc.UA.PubSub.Configuration.Extensions
Imports OpcLabs.EasyOpc.UA.PubSub.InformationModel
Imports OpcLabs.EasyOpc.UA.PubSub.InformationModel.Extensions

Namespace PubSub._IUAReadOnlyPubSubConfiguration
    Partial Friend Class GetMethods
        Public Shared Sub PubSubComponents()

            ' Instantiate the publish-subscribe client object.
            Dim publishSubscribeClient = New EasyUAPublishSubscribeClient()

            Try
                Console.WriteLine("Loading the configuration...")
                ' Load the PubSub configuration from a file. The file itself is at the root of the project, and we have
                ' specified that it has to be copied to the project's output directory.
                Dim pubSubConfiguration As IUAReadOnlyPubSubConfiguration =
                    publishSubscribeClient.LoadReadOnlyConfiguration("UADemoPublisher-Default.uabinary")

                ' Alternatively, using the statement below, you can access a live configuration residing in an OPC UA
                ' Server with appropriate information model.
                'Dim pubSubConfiguration As IUAReadOnlyPubSubConfiguration =
                '    publishSubscribeClient.AccessReadOnlyConfiguration("opc.tcp://localhost:48010")

                ' Get the names of PubSub connections in the configuration, regardless of the folder they reside in.
                Dim pubSubConnectionNames = pubSubConfiguration.ListConnectionNames()
                For Each pubSubConnectionName As String In pubSubConnectionNames
                    Console.WriteLine($"PubSub connection: {pubSubConnectionName}")

                    ' You can use the statement below to obtain parameters of the PubSub connection.
                    'Dim connectionElement As UAPubSubConnectionElement =
                    '    pubSubConfiguration.GetConnectionElement(pubSubConnectionName)

                    ' Get names of the writer groups on this PubSub connection.
                    Dim writerGroupNames = pubSubConfiguration.ListWriterGroupNames(pubSubConnectionName)
                    For Each writerGroupName As String In writerGroupNames
                        Console.WriteLine($"  Writer group: {writerGroupName}")

                        ' You can use the statement below to obtain parameters of the writer group.
                        'Dim writerGroupElement As UAWriterGroupElement =
                        '    pubSubConfiguration.GetWriterGroupElement(pubSubConnectionName, writerGroupName)

                        ' Get names of the dataset writers on this writer group.
                        Dim dataSetWriterNames =
                            pubSubConfiguration.ListDataSetWriterNames(pubSubConnectionName, writerGroupName)
                        For Each dataSetWriterName As String In dataSetWriterNames
                            Console.WriteLine($"    Dataset writer: {dataSetWriterName}")

                            ' You can use the statement below to obtain parameters of the dataset writer.
                            'Dim dataSetWriterElement As UADataSetWriterElement = pubSubConfiguration.GetDataSetWriterElement(
                            '    pubSubConnectionName, writerGroupName, dataSetWriterName)
                        Next dataSetWriterName
                    Next writerGroupName
                Next pubSubConnectionName
            Catch uaException As UAException
                Console.WriteLine("*** Failure: {0}", uaException.GetBaseException.Message)
            End Try

            Console.WriteLine("Finished...")
        End Sub
    End Class

    ' Example output
    '
    'Loading the configuration...
    'PubSub connection FixedLayoutConnection
    '  Writer group: FixedLayoutGroup
    '    Dataset writer: SimpleWriter
    '    Dataset writer: AllTypesWriter
    '    Dataset writer: MassTestWriter
    'PubSub connection: DynamicLayoutConnection
    '  Writer group: DynamicLayoutGroup
    '    Dataset writer: SimpleWriter
    '    Dataset writer: MassTestWriter
    '    Dataset writer: AllTypes-DynamicWriter
    '    Dataset writer: EventSimpleWriter
    'PubSub connection: FlexibleLayoutConnection
    '  Writer group: FlexibleLayoutGroup
    '    Dataset writer: SimpleWriter
    '    Dataset writer: MassTestWriter
    '    Dataset writer: AllTypes-DynamicWriter
    'Finished.

End Namespace
// This example obtains and prints out information about PubSub connections, writer groups, and dataset writers in the
// OPC UA PubSub configuration.

class procedure GetMethods.PubSubComponents;
var
  //DataSetWriterElement: _UADataSetWriterElement;
  DataSetWriterName: string;
  DataSetWriterNames: _StringCollection;
  //EndpointDescriptor: _UAEndpointDescriptor;
  I, J, K: Integer;
  //PubSubConnectionElement: _UAPubSubConnectionElement;
  PubSubConnectionName: string;
  ConnectionNames: _StringCollection;
  PublishSubscribeClient: _EasyUAPublishSubscribeClient;
  PubSubConfiguration: _UAReadOnlyPubSubConfiguration;
  //WriterGroupElement: _UAWriterGroupElement;
  WriterGroupName: string;
  WriterGroupNames: _StringCollection;
begin
  // Instantiate the publish-subscribe client object.
  PublishSubscribeClient := CoEasyUAPublishSubscribeClient.Create;

  try
    WriteLn('Loading the configuration...');
    // Load the PubSub configuration from a file. The file itself is included alongside the script.
    PubSubConfiguration := PublishSubscribeClient.LoadReadOnlyConfiguration('UADemoPublisher-Default.uabinary');

    // Alternatively, using the statements below, you can access a live configuration residing in an OPC UA Server
    // with appropriate information model.
    //EndpointDescriptor := CoUAEndpointDescriptor.Create;
    //EndpointDescriptor.UrlString := 'opc.tcp://localhost:48010';
    //PubSubConfiguration := PublishSubscribeClient.AccessReadOnlyConfiguration(EndpointDescriptor);

    // Get the names of PubSub connections in the configuration.
    ConnectionNames := PubSubConfiguration.ListConnectionNames;

    for I := 0 to ConnectionNames.Count-1 do
    begin
      PubSubConnectionName := ConnectionNames[I];
      WriteLn('PubSub connection: ', PubSubConnectionName);

      // You can use the statement below to obtain parameters of the PubSub connection.
      //PubSubConnectionElement := PubSubConfiguration.GetConnectionElement(PubSubConnectionName);

      // Get names of the writer groups on this PubSub connection.
      WriterGroupNames := PubSubConfiguration.ListWriterGroupNames(PubSubConnectionName);
      for J := 0 to WriterGroupNames.Count-1 do
      begin
        WriterGroupName := WriterGroupNames[J];
        WriteLn('  Writer group: ', WriterGroupName);

        // You can use the statement below to obtain parameters of the writer group.
        //WriterGroupElement := PubSubConfiguration.GetWriterGroupElement(PubSubConnectionName, WriterGroupName);

        // Get names of the dataset writers on this writer group.
        DataSetWriterNames := PubSubConfiguration.ListDataSetWriterNames(PubSubConnectionName, WriterGroupName);
        for K := 0 to DataSetWriterNames.Count-1 do
        begin
          DataSetWriterName := DataSetWriterNames[K];
          WriteLn('    Dataset writer: ', DataSetWriterName);

          // You can use the statement below to obtain parameters of the dataset writer.
          //DataSetWriterElement := PubSubConfiguration.GetDataSetWriterElement(PubSubConnectionName, WriterGroupName, DataSetWriterName);
        end;
      end;
    end;
  except
    on E: EOleException do
    begin
      WriteLn(Format('*** Failure: %s', [E.GetBaseException.Message]));
    end;
  end;

  WriteLn('Finished.');
end;

// Example output:
//
//Loading the configuration...
//PubSub connection: FixedLayoutConnection
//  Writer group: FixedLayoutGroup
//    Dataset writer: SimpleWriter
//    Dataset writer: AllTypesWriter
//    Dataset writer: MassTestWriter
//PubSub connection: DynamicLayoutConnection
//  Writer group: DynamicLayoutGroup
//    Dataset writer: SimpleWriter
//    Dataset writer: MassTestWriter
//    Dataset writer: AllTypes-DynamicWriter
//    Dataset writer: EventSimpleWriter
//PubSub connection: FlexibleLayoutConnection
//  Writer group: FlexibleLayoutGroup
//    Dataset writer: SimpleWriter
//    Dataset writer: MassTestWriter
//    Dataset writer: AllTypes-DynamicWriter
//Finished.
Rem This example obtains and prints out information about PubSub connections, writer groups, and dataset writers in the
Rem OPC UA PubSub configuration.

Option Explicit

' Instantiate the publish-subscribe client object.
Dim PublishSubscribeClient: Set PublishSubscribeClient = CreateObject("OpcLabs.EasyOpc.UA.PubSub.InformationModel.EasyUAPublishSubscribeClient")

On Error Resume Next
DumpPubSubComponents
If Err.Number <> 0 Then
    WScript.Echo "*** Failure: " & Err.Source & ": " & Err.Description
    WScript.Quit
End If
On Error Goto 0

WScript.Echo "Finished."



Sub DumpPubSubComponents()
    WScript.Echo "Loading the configuration..."
    ' Load the PubSub configuration from a file. The file itself is included alongside the script.
    Dim PubSubConfiguration: Set PubSubConfiguration = PublishSubscribeClient.LoadReadOnlyConfiguration("UADemoPublisher-Default.uabinary")

    ' Alternatively, using the statements below, you can access a live configuration residing in an OPC UA Server
    ' with appropriate information model.
    'Dim EndpointDescriptor: Set EndpointDescriptor = CreateObject("OpcLabs.EasyOpc.UA.UAEndpointDescriptor")
    'EndpointDescriptor.UrlString = "opc.tcp://localhost:48010"
    'Dim PubSubConfiguration: Set PubSubConfiguration = PublishSubscribeClient.AccessReadOnlyConfiguration(EndpointDescriptor)

    ' Get the names of PubSub connections in the configuration.
    Dim ConnectionNames: Set ConnectionNames = PubSubConfiguration.ListConnectionNames
    Dim pubSubConnectionName: For Each pubSubConnectionName In ConnectionNames
        WScript.Echo "PubSub connection: " & pubSubConnectionName

        ' You can use the statement below to obtain parameters of the PubSub connection.
        'Dim PubSubConnectionElement: Set PubSubConnectionElement = PubSubConfiguration.GetConnectionElement(pubSubConnectionName)

        ' Get names of the writer groups on this PubSub connection.
        Dim WriterGroupNames: Set WriterGroupNames = PubSubConfiguration.ListWriterGroupNames(pubSubConnectionName)
        Dim writerGroupName: For Each writerGroupName In WriterGroupNames
            WScript.Echo "  Writer group: " & writerGroupName

            ' You can use the statement below to obtain parameters of the writer group.
            'Dim WriterGroupElement: Set WriterGroupElement = PubSubConfiguration.GetWriterGroupElement(pubSubConnectionName, writerGroupName)

            ' Get names of the dataset writers on this writer group.
            Dim DataSetWriterNames: Set DataSetWriterNames = PubSubConfiguration.ListDataSetWriterNames(pubSubConnectionName, writerGroupName)
            Dim dataSetWriterName: For Each dataSetWriterName In DataSetWriterNames
                WScript.Echo "    Dataset writer: " & dataSetWriterName

                ' You can use the statement below to obtain parameters of the dataset writer.
                'Dim DataSetWriterElement: Set DataSetWriterElement = _
                '    PubSubConfiguration.GetDataSetWriterElement(pubSubConnectionName, writerGroupName, dataSetWriterName)
            Next
        Next
    Next
End Sub



' Example output:
'
'Loading the configuration...
'PubSub connection: FixedLayoutConnection
'  Writer group: FixedLayoutGroup
'    Dataset writer: SimpleWriter
'    Dataset writer: AllTypesWriter
'    Dataset writer: MassTestWriter
'PubSub connection: DynamicLayoutConnection
'  Writer group: DynamicLayoutGroup
'    Dataset writer: SimpleWriter
'    Dataset writer: MassTestWriter
'    Dataset writer: AllTypes-DynamicWriter
'    Dataset writer: EventSimpleWriter
'PubSub connection: FlexibleLayoutConnection
'  Writer group: FlexibleLayoutGroup
'    Dataset writer: SimpleWriter
'    Dataset writer: MassTestWriter
'    Dataset writer: AllTypes-DynamicWriter
'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

See Also