OPC Studio User's Guide and Reference
AccessReadOnlyConfiguration Method (EasyUAPublishSubscribeClientCore)
Example 



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OpcLabs.EasyOpcUA Assembly > OpcLabs.EasyOpc.UA.PubSub.InformationModel Namespace > EasyUAPublishSubscribeClientCore Class : AccessReadOnlyConfiguration Method
The endpoint descriptor of the OPC UA server containing the PubSub information model.

Because the OpcLabs.EasyOpc.UA.UAEndpointDescriptor has implicit conversions from System.String and System.Uri, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a string (representing the endpoint URL, or a so-called OPC UA endpoint descriptor string), or a System.Uri object, in place of this parameter, and the corresponding endpoint descriptor will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can use the OpcLabs.EasyOpc.UA.UAEndpointDescriptor.FromString or OpcLabs.EasyOpc.UA.UAEndpointDescriptor.FromUri static method instead.

Also, because the OpcLabs.EasyOpc.UA.Discovery.UAApplicationElement and OpcLabs.EasyOpc.UA.Discovery.UADiscoveryElement have an implicit conversion to OpcLabs.EasyOpc.UA.UAEndpointDescriptor, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a OpcLabs.EasyOpc.UA.Discovery.UAApplicationElement or OpcLabs.EasyOpc.UA.Discovery.UADiscoveryElement (results from OPC UA discovery) in place of this parameter, and the corresponding endpoint descriptor will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can convert a (non-null) OpcLabs.EasyOpc.UA.Discovery.UAApplicationElement or OpcLabs.EasyOpc.UA.Discovery.UADiscoveryElement to OpcLabs.EasyOpc.UA.UAEndpointDescriptor using the OpcLabs.EasyOpc.UA.Discovery.UAApplicationElement.ToUAEndpointDescriptor or OpcLabs.EasyOpc.UA.Discovery.UADiscoveryElement.ToUAEndpointDescriptor method instead.

If you are using OPC Wizard (for server development), an implicit conversion from OpcLabs.EasyOpc.UA.EasyUAServerCore can be used in the same way to simply pass the server object in place of this parameter, which will use its OpcLabs.EasyOpc.UA.EasyUAServerCore.EffectiveServerDescriptor property for the connection.

The value of this parameter cannot be null (Nothing in Visual Basic).

Gives read-only access to PubSub configuration provided by the specified OPC UA server.
Syntax
'Declaration
 
Public Function AccessReadOnlyConfiguration( _
   ByVal endpointDescriptor As UAEndpointDescriptor _
) As IUAReadOnlyPubSubConfiguration
 
'Usage
 
Dim instance As EasyUAPublishSubscribeClientCore
Dim endpointDescriptor As UAEndpointDescriptor
Dim value As IUAReadOnlyPubSubConfiguration
 
value = instance.AccessReadOnlyConfiguration(endpointDescriptor)

Parameters

endpointDescriptor
The endpoint descriptor of the OPC UA server containing the PubSub information model.

Because the OpcLabs.EasyOpc.UA.UAEndpointDescriptor has implicit conversions from System.String and System.Uri, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a string (representing the endpoint URL, or a so-called OPC UA endpoint descriptor string), or a System.Uri object, in place of this parameter, and the corresponding endpoint descriptor will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can use the OpcLabs.EasyOpc.UA.UAEndpointDescriptor.FromString or OpcLabs.EasyOpc.UA.UAEndpointDescriptor.FromUri static method instead.

Also, because the OpcLabs.EasyOpc.UA.Discovery.UAApplicationElement and OpcLabs.EasyOpc.UA.Discovery.UADiscoveryElement have an implicit conversion to OpcLabs.EasyOpc.UA.UAEndpointDescriptor, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a OpcLabs.EasyOpc.UA.Discovery.UAApplicationElement or OpcLabs.EasyOpc.UA.Discovery.UADiscoveryElement (results from OPC UA discovery) in place of this parameter, and the corresponding endpoint descriptor will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can convert a (non-null) OpcLabs.EasyOpc.UA.Discovery.UAApplicationElement or OpcLabs.EasyOpc.UA.Discovery.UADiscoveryElement to OpcLabs.EasyOpc.UA.UAEndpointDescriptor using the OpcLabs.EasyOpc.UA.Discovery.UAApplicationElement.ToUAEndpointDescriptor or OpcLabs.EasyOpc.UA.Discovery.UADiscoveryElement.ToUAEndpointDescriptor method instead.

If you are using OPC Wizard (for server development), an implicit conversion from OpcLabs.EasyOpc.UA.EasyUAServerCore can be used in the same way to simply pass the server object in place of this parameter, which will use its OpcLabs.EasyOpc.UA.EasyUAServerCore.EffectiveServerDescriptor property for the connection.

The value of this parameter cannot be null (Nothing in Visual Basic).

Return Value

Returns an interface that provides read-only access to PubSub configuration.

This method never returns null (Nothing in Visual Basic).

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.

Remarks

You can use the HasConfigurationModel method to determine whether the given server provides a PubSub configuration model. Operations on the returned OpcLabs.EasyOpc.UA.PubSub.Configuration.IUAReadOnlyPubSubConfiguration will fail if it does not.

Example
// This example obtains and prints out information about all published datasets in the OPC UA PubSub configuration.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in C# on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-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 OpcLabs.BaseLib.Collections.Specialized;
using OpcLabs.EasyOpc.UA.OperationModel;
using OpcLabs.EasyOpc.UA.PubSub.Configuration;
using OpcLabs.EasyOpc.UA.PubSub.Configuration.Extensions;
using OpcLabs.EasyOpc.UA.PubSub.InformationModel;
using OpcLabs.EasyOpc.UA.PubSub.InformationModel.Extensions;

namespace UASubscriberDocExamples.PubSub._IUAReadOnlyPubSubConfiguration
{
    partial class GetMethods
    {
        public static void PublishedDataSets()
        {
            // 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 all published datasets in the PubSub configuration.
                StringCollection publishedDataSetNames = pubSubConfiguration.ListAllPublishedDataSetNames();

                foreach (string publishedDataSetName in publishedDataSetNames)
                {
                    Console.WriteLine($"Published dataset: {publishedDataSetName}");

                    // You can use the statement below to obtain parameters of the published dataset.
                    //UAPublishedDataSetElement publishedDataSetElement = 
                    //    pubSubConfiguration.GetPublishedDataSetElement(publishedDataSetName);
                }
            }
            catch (UAException uaException)
            {
                Console.WriteLine($"*** Failure: {uaException.InnerException.Message}");
            }

            Console.WriteLine("Finished.");
        }

        // Example output:
        //
        //Loading the configuration...
        //Published dataset: Simple
        //Published dataset: AllTypes
        //Published dataset: MassTest
        //Published dataset: AllTypes-Dynamic
        //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