Delete Method (EasyUAFileTransferClientCore)

Endpoint descriptor. Identifies the OPC-UA server.

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 ToUAEndpointDescriptor or 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).

Deletes an OPC UA file or directory, organized under an existing directory.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
Public Sub Delete( _
   ByVal endpointDescriptor As UAEndpointDescriptor, _
   ByVal directoryNodeDescriptor As UANodeDescriptor, _
   ByVal existingFileOrDirectoryNodeId As UANodeId _
)

'Usage
 
Dim instance As EasyUAFileTransferClientCore
Dim endpointDescriptor As UAEndpointDescriptor
Dim directoryNodeDescriptor As UANodeDescriptor
Dim existingFileOrDirectoryNodeId As UANodeId
 
instance.Delete(endpointDescriptor, directoryNodeDescriptor, existingFileOrDirectoryNodeId)

public void Delete( 
   UAEndpointDescriptor endpointDescriptor,
   UANodeDescriptor directoryNodeDescriptor,
   UANodeId existingFileOrDirectoryNodeId
)

public:
void Delete( 
   UAEndpointDescriptor^ endpointDescriptor,
   UANodeDescriptor^ directoryNodeDescriptor,
   UANodeId^ existingFileOrDirectoryNodeId
)

Parameters

endpointDescriptor

Endpoint descriptor. Identifies the OPC-UA server.

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

directoryNodeDescriptor

Node descriptor of the OPC UA directory.

Because the OpcLabs.EasyOpc.UA.UANodeDescriptor has implicit conversions from OpcLabs.EasyOpc.UA.AddressSpace.UANodeId, OpcLabs.EasyOpc.UA.AddressSpace.UANodeElement, OpcLabs.EasyOpc.UA.Navigation.UABrowsePath and System.String, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a OpcLabs.EasyOpc.UA.AddressSpace.UANodeId object (representing the Id of the OPC UA node), a node element object (from OPC UA browsing), OpcLabs.EasyOpc.UA.Navigation.UABrowsePath object (representing OPC UA absolute browse path), or a string (with expanded node Id text) in place of this parameter, and the corresponding node 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.UANodeDescriptor.FromString, OpcLabs.EasyOpc.UA.UANodeDescriptor.FromUABrowsePath, OpcLabs.EasyOpc.UA.UANodeDescriptor.FromUANodeElement or OpcLabs.EasyOpc.UA.UANodeDescriptor.FromUANodeId static method instead.

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

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

existingFileOrDirectoryNodeId

A node descriptor of the file or directory to delete.

Because the OpcLabs.EasyOpc.UA.AddressSpace.UANodeId has an implicit conversion from System.String, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a string (representing the expanded text of the nodeId) in place of this parameter, and the corresponding OPC UA node Id will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can use the OpcLabs.EasyOpc.UA.AddressSpace.UANodeId.UANodeId Constructor(String) constructor instead.

The value of this parameter cannot be 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.
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.

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 corresponds to (but is not fully identical with) the OPC UA File Transfer Method .

The directoryNodeDescriptor must be an existing node in the server, of object type OpcLabs.EasyOpc.UA.AddressSpace.Standard.UAObjectTypeIds.FileDirectoryType.

For existingFileOrDirectoryNodeId, "In the case of a directory, all file and directory Objects below the directory to delete are deleted recursively."

This method will delete either a file or directory, as long as the existingFileOrDirectoryNodeId refers to an OPC UA file or directory object. If you want to delete a file and be sure that you do not delete a directory, use the IEasyUAFileTransferExtension.DeleteFile extension method or one of its other overloads. If you want to delete a directory and be sure that you do not delete a file, use the IEasyUAFileTransferExtension.DeleteDirectory extension method or one of its other overloads.

This method will throw an exception if the object you are trying to delete does not exist. If you want to assure object deletion and do nothing if the object does not exist, you one of the following extension methods:

Recommendation: Whenever possible, do not use this method directly, and use a higher-level abstraction instead. You can obtain a writable file provider (using IEasyUAFileTransferExtension.GetWritableFileProvider). For directories, you can obtain writable directory contents (using OpcLabs.BaseLib.Extensions.FileProviders.IWritableDirectory.GetWritableDirectoryContents), and then call the OpcLabs.BaseLib.Extensions.FileProviders.IWritableDirectoryContents.Delete method to delete the directory. For files, you can obtain writable file info (using OpcLabs.BaseLib.Extensions.FileProviders.IWritableDirectory.GetWritableFileInfo) and then call the OpcLabs.BaseLib.Extensions.FileProviders.IWritableFileInfo.Delete method to delete the file.

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

EasyUAFileTransferClientCore Class
EasyUAFileTransferClientCore Members
CreateDirectory Method
CreateFile Method

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