QuickOPC User's Guide and Reference
FindRootDirectory Method



OpcLabs.EasyOpcUA Assembly > OpcLabs.EasyOpc.UA.FileTransfer Namespace > IEasyUAFileTransferExtension Class : FindRootDirectory Method
The OPC UA file transfer object that will perform the operation.
Endpoint descriptor. Identifies the OPC-UA server.
The directory node descriptor of the file or directory for which the root directory should be found.
Finds a root directory of the specified OPC UA file or directory object.
Syntax
'Declaration
 
<ExtensionAttribute()>
<CanBeNullAttribute()>
Public Shared Function FindRootDirectory( _
   ByVal fileTransfer As IEasyUAFileTransfer, _
   ByVal endpointDescriptor As UAEndpointDescriptor, _
   ByVal fileOrDirectoryNodeDescriptor As UANodeDescriptor _
) As UANodeDescriptor
'Usage
 
Dim fileTransfer As IEasyUAFileTransfer
Dim endpointDescriptor As UAEndpointDescriptor
Dim fileOrDirectoryNodeDescriptor As UANodeDescriptor
Dim value As UANodeDescriptor
 
value = IEasyUAFileTransferExtension.FindRootDirectory(fileTransfer, endpointDescriptor, fileOrDirectoryNodeDescriptor)

Parameters

fileTransfer
The OPC UA file transfer object that will perform the operation.
endpointDescriptor
Endpoint descriptor. Identifies the OPC-UA server.
fileOrDirectoryNodeDescriptor
The directory node descriptor of the file or directory for which the root directory should be found.

Return Value

Returns a node descriptor of the root directory object, if the root directory was found. Returns null otherwise.
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.

Remarks

In typical file systems, it is always possible to find a root. Also, in them, a root for the root is the root itself. In OPC UA file transfer, however, files can also appear standalone, and such files have no associated parent or root directory.

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