AccessOrLoadReadOnlyConfiguration Method (_EasyUAPublishSubscribeClient)

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.

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).

Provides read-only access to the PubSub configuration provided by an OPC UA server, either by using the PubSub configuration model, or optionally by loading it from an OPC UA file object.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
<NotNullAttribute()>
Function AccessOrLoadReadOnlyConfiguration( _
   ByVal endpointDescriptor As Object, _
   ByVal pubSubConfigurationAccessMethod As UAPubSubConfigurationAccessMethod _
) As _UAReadOnlyPubSubConfiguration

'Usage
 
Dim instance As _EasyUAPublishSubscribeClient
Dim endpointDescriptor As Object
Dim pubSubConfigurationAccessMethod As UAPubSubConfigurationAccessMethod
Dim value As _UAReadOnlyPubSubConfiguration
 
value = instance.AccessOrLoadReadOnlyConfiguration(endpointDescriptor, pubSubConfigurationAccessMethod)

[NotNull()]
_UAReadOnlyPubSubConfiguration AccessOrLoadReadOnlyConfiguration( 
   object endpointDescriptor,
   UAPubSubConfigurationAccessMethod pubSubConfigurationAccessMethod
)

[NotNull()]
_UAReadOnlyPubSubConfiguration^ AccessOrLoadReadOnlyConfiguration( 
   Object^ endpointDescriptor,
   UAPubSubConfigurationAccessMethod pubSubConfigurationAccessMethod
)

Parameters

endpointDescriptor

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

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

pubSubConfigurationAccessMethod

Determines whether it is allowed to load the configuration from the file node in the information model, if available.

Return Value

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

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

Exceptions

Exception Description

Exception	Description
System.ArgumentNullException	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.
System.ComponentModel.InvalidEnumArgumentException	An invalid enumeration value was used. 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.
OpcLabs.EasyOpc.UA.OperationModel.UAException	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.

System.ArgumentNullException

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.

System.ComponentModel.InvalidEnumArgumentException

An invalid enumeration value was used.

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.

OpcLabs.EasyOpc.UA.OperationModel.UAException

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.

Remarks

This method optionally detects and possibly uses a PubSubConfiguration file node defined in OPC UA 1.05, or a vendor specific ConfigurationFile file node, present in servers implemented with Unified Automation (C++) toolkit.

Loading the configuration from a file node is typically faster than accessing it through individual nodes in the information model, but it only provides a one-time snapshot of the configuration.

This member or type is for use from COM. It is not meant to be used from .NET or Python. Refer to the corresponding .NET member or type instead, if you are developing in .NET or Python.

This is an extension method (info: C#, VB.NET). In languages that have support for extensions methods (such as C# and VB.NET), you can use the extension method as if it were a regular method on the object that is its first parameter. In other languages (such as with Python.NET), you will call the extension as a static method, and pass it the object on which it acts as its first parameter.

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

_EasyUAPublishSubscribeClient Interface
_EasyUAPublishSubscribeClient Members

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