CreateDirectory Method (IEasyUAFileTransfer)

Creates a new OPC UA directory, organized under an existing one.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
<NotNullAttribute()>
Function CreateDirectory( _
   ByVal endpointDescriptor As UAEndpointDescriptor, _
   ByVal directoryNodeDescriptor As UANodeDescriptor, _
   ByVal directoryName As String _
) As UANodeId

'Usage
 
Dim instance As IEasyUAFileTransfer
Dim endpointDescriptor As UAEndpointDescriptor
Dim directoryNodeDescriptor As UANodeDescriptor
Dim directoryName As String
Dim value As UANodeId
 
value = instance.CreateDirectory(endpointDescriptor, directoryNodeDescriptor, directoryName)

[NotNull()]
UANodeId CreateDirectory( 
   UAEndpointDescriptor endpointDescriptor,
   UANodeDescriptor directoryNodeDescriptor,
   string directoryName
)

[NotNull()]
UANodeId^ CreateDirectory( 
   UAEndpointDescriptor^ endpointDescriptor,
   UANodeDescriptor^ directoryNodeDescriptor,
   String^ directoryName
)

Parameters

endpointDescriptor

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).

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).

directoryName

The name of the directory create.

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

Return Value

Returns the node Id of the created directory object.

Because there is an implicit conversion from OpcLabs.EasyOpc.UA.AddressSpace.UANodeId to OpcLabs.EasyOpc.UA.UANodeDescriptor, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use the returned OpcLabs.EasyOpc.UA.AddressSpace.UANodeId in any place where the OpcLabs.EasyOpc.UA.UANodeDescriptor is expected as input, and the corresponding node descriptor will be constructed automatically.

Also, because the OpcLabs.EasyOpc.UA.AddressSpace.UANodeId has an implicit conversion to System.String, and it converts to the expanded text of the node Id (OpcLabs.EasyOpc.UA.AddressSpace.UANodeId.ExpandedText), in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use the returned OpcLabs.EasyOpc.UA.AddressSpace.UANodeId in any place where expanded text of a node Id (a string) is expected as input, and the corresponding expanded text will be taken automatically from the node Id.

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.
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.

The directoryName "is used for the BrowseName and DisplayName of the directory object and also for the directory in the file system. For the BrowseName, the directoryName is used for the name part of the QualifiedName.The namespace index is Server specific. For the DisplayName, the directoryName is used for the text part of the LocalizedText. The locale part is Server specific."

This method will throw an exception if the directory you are attempting to create already exists.

If you do not know whether the directory you are creating already exists, and want to assure its creation, use the IEasyUAFileTransferExtension.FindOrCreateDirectory extension method instead. If you want to assure creation of a directory that is possibly deeper nested, use the IEasyUAFileTransferExtension.FindOrCreateAllDirectories or one of its other overloads.

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) and a writable directory contents (using OpcLabs.BaseLib.Extensions.FileProviders.IWritableDirectory.GetWritableDirectoryContents), and then call the OpcLabs.BaseLib.Extensions.FileProviders.IWritableDirectoryContents.Create or OpcLabs.BaseLib.Extensions.FileProviders.IWritableDirectoryContentsExtension.CreateSubdirectory method to create the directory.

Example

CSharp
VB.NET
Python

// Shows how to create and delete OPC UA directories, using the file transfer client.
// Note: Consider using a higher-level abstraction, OPC UA file provider, instead.
//
// 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.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.AddressSpace;
using OpcLabs.EasyOpc.UA.Extensions;
using OpcLabs.EasyOpc.UA.FileTransfer;
using OpcLabs.EasyOpc.UA.OperationModel;

namespace UADocExamples.FileTransfer._EasyUAFileTransferClient
{
    class CreateDirectoryAndDelete
    {
        public static void Main1()
        {
            // Unified Automation .NET based demo server (UaNETServer/UaServerNET.exe)
            var endpointDescriptor = new UAEndpointDescriptor("opc.tcp://localhost:48030")
                .WithUserNameIdentity("john", "master");

            // An object that aggregates an OPC UA file system.
            UANodeDescriptor objectDescriptor = "nsu=http://www.unifiedautomation.com/DemoServer/ ;s=Demo.Files";

            // Create a random number generator - will be used for file/directory names.
            var random = new Random();
            
            // Instantiate the file transfer client object
            var fileTransferClient = new EasyUAFileTransferClient();

            // Create two directories, and one nested directory, and delete the first one.
            try
            {
                // The file system node is a root directory of the file system.
                Console.WriteLine("Getting file system...");
                UANodeDescriptor fileSystemNodeDescriptor = fileTransferClient.GetFileSystem(endpointDescriptor, objectDescriptor);

                string directoryName1 = "MyDirectory1-" + random.Next();
                Console.WriteLine($"Creating first directory, '{directoryName1}'...");
                UANodeId directoryNodeId1 = fileTransferClient.CreateDirectory(endpointDescriptor, fileSystemNodeDescriptor, directoryName1);
                Console.WriteLine($"Node Id of the first directory: {directoryNodeId1}");

                string directoryName2 = "MyDirectory2-" + random.Next();
                Console.WriteLine($"Creating second directory, '{directoryName2}'...");
                UANodeId directoryNodeId2 = fileTransferClient.CreateDirectory(endpointDescriptor, fileSystemNodeDescriptor, directoryName2);
                Console.WriteLine($"Node Id of the second directory: {directoryNodeId2}");

                string nestedDirectoryName = "MyDirectory3-" + random.Next();
                Console.WriteLine($"Creating nested directory, '{nestedDirectoryName}'...");
                // Note how directoryNodeId2 (a parent directory) is passed as the 2nd argument to the CreateDirectory method.
                UANodeId nestedDirectoryNodeId = fileTransferClient.CreateDirectory(endpointDescriptor, directoryNodeId2, nestedDirectoryName);
                Console.WriteLine($"Node Id of the nested directory: {nestedDirectoryNodeId}");

                // At this moment, the directory structure we have created looks like this:
                // * MyDirectory1
                // * MyDirectory2
                // * * MyDirectory3

                Console.WriteLine("Deleting the first directory...");
                fileTransferClient.DeleteDirectory(endpointDescriptor, fileSystemNodeDescriptor, directoryName1);
            }
            catch (UAException uaException)
            {
                Console.WriteLine("*** Failure: {0}", uaException.GetBaseException().Message);
                return;
            }

            Console.WriteLine("Finished...");
        }
    }
}

' Shows how to create and delete OPC UA directories, using the file transfer client.
' Note: Consider using a higher-level abstraction, OPC UA file provider, instead.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
' OPC client and subscriber examples in VB.NET on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VBNET .
' 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.

Imports OpcLabs.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.AddressSpace
Imports OpcLabs.EasyOpc.UA.Extensions
Imports OpcLabs.EasyOpc.UA.FileTransfer
Imports OpcLabs.EasyOpc.UA.OperationModel

Namespace FileTransfer._EasyUAFileTransferClient

    Friend Class CreateDirectoryAndDelete

        Public Shared Sub Main1()

            ' Unified Automation .NET based demo server (UaNETServer/UaServerNET.exe)
            Dim endpointDescriptor As UAEndpointDescriptor =
                New UAEndpointDescriptor("opc.tcp://localhost:48030") _
                .WithUserNameIdentity("john", "master")

            ' An object that aggregates an OPC UA file system.
            Dim objectDescriptor As UANodeDescriptor = "nsu=http://www.unifiedautomation.com/DemoServer/ ;s=Demo.Files"

            ' Create a random number generator - will be used for file/directory names.
            Dim random = New Random

            ' Instantiate the file transfer client object
            Dim fileTransferClient = New EasyUAFileTransferClient

            ' Create two directories, and one nested directory, and delete the first one.
            Try
                ' The file system node is a root directory of the file system.
                Console.WriteLine("Getting file system...")
                Dim fileSystemNodeDescriptor As UANodeDescriptor = fileTransferClient.GetFileSystem(endpointDescriptor, objectDescriptor)

                Dim directoryName1 As String = "MyDirectory1-" & random.Next()
                Console.WriteLine($"Creating first directory, '{directoryName1}'...")
                Dim directoryNodeId1 As UANodeId = fileTransferClient.CreateDirectory(endpointDescriptor, fileSystemNodeDescriptor, directoryName1)
                Console.WriteLine($"Node Id of the first directory: {directoryNodeId1}")

                Dim directoryName2 As String = "MyDirectory2-" & random.Next()
                Console.WriteLine($"Creating second directory, '{directoryName2}'...")
                Dim directoryNodeId2 As UANodeId = fileTransferClient.CreateDirectory(endpointDescriptor, fileSystemNodeDescriptor, directoryName2)
                Console.WriteLine($"Node Id of the second directory: {directoryNodeId2}")

                Dim nestedDirectoryName As String = "MyDirectory3-" & random.Next()
                Console.WriteLine($"Creating nested directory, '{nestedDirectoryName}'...")
                ' Note how directoryNodeId2 (a parent directory) Is passed as the 2nd argument to the CreateDirectory method.
                Dim nestedDirectoryNodeId As UANodeId = fileTransferClient.CreateDirectory(endpointDescriptor, directoryNodeId2, nestedDirectoryName)
                Console.WriteLine($"Node Id of the nested directory: {nestedDirectoryNodeId}")

                ' At this moment, the directory structure we have created looks Like this
                ' * MyDirectory1
                ' * MyDirectory2
                ' * * MyDirectory3

                Console.WriteLine("Deleting the first directory...")
                fileTransferClient.DeleteDirectory(endpointDescriptor, fileSystemNodeDescriptor, directoryName1)
            Catch uaException As UAException
                Console.WriteLine("*** Failure: {0}", uaException.GetBaseException.Message)
                Exit Sub
            End Try

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

# Shows how to create and delete OPC UA directories, using the file transfer client.
# Note: Consider using a higher-level abstraction, OPC UA file provider, instead.
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
# OPC client and subscriber examples in Python on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-Python .
# 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.
# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc
import random

# Import .NET namespaces.
from OpcLabs.EasyOpc.UA import *
from OpcLabs.EasyOpc.UA.Extensions import *
from OpcLabs.EasyOpc.UA.FileTransfer import *
from OpcLabs.EasyOpc.UA.OperationModel import *


# Unified Automation .NET based demo server (UaNETServer/UaServerNET.exe).
endpointDescriptor = UAEndpointDescriptor('opc.tcp://localhost:48030')
endpointDescriptor = UAEndpointDescriptorExtension.WithUserNameIdentity(endpointDescriptor,'john', 'master')

# An object that aggregates an OPC UA file system.
objectDescriptor = UANodeDescriptor('nsu=http://www.unifiedautomation.com/DemoServer/ ;s=Demo.Files')

# Create a random number generator - will be used for file/directory names.
random = random.Random()

# Instantiate the file transfer client object.
fileTransferClient = EasyUAFileTransferClient()

# Prevent prompt to trust the server certificate (INSECURE, used just for smooth example flow).
EasyUAClient.SharedParameters.EngineParameters.CertificateAcceptancePolicy.TrustEndpointUrlString(
    endpointDescriptor.UrlString)

# Create two directories, and one nested directory, and delete the first one.
try:
    # The file system node is a root directory of the file system.
    print('Getting file system...')
    fileSystemNodeDescriptor = IEasyUAFileTransferExtension.GetFileSystem(fileTransferClient,
                                                                          endpointDescriptor, objectDescriptor)

    directoryName1 = 'MyDirectory1-' + str(random.randint(0, 999_999_999))
    print("Creating first directory, '", directoryName1, "'...", sep='')
    directoryNodeId1 = fileTransferClient.CreateDirectory(endpointDescriptor,
                                                          fileSystemNodeDescriptor,
                                                          directoryName1)
    print('Node Id of the first directory: ', directoryNodeId1, sep='')

    directoryName2 = 'MyDirectory2-' + str(random.randint(0, 999_999_999))
    print("Creating second directory, '", directoryName2, "'...", sep='')
    directoryNodeId2 = fileTransferClient.CreateDirectory(endpointDescriptor,
                                                          fileSystemNodeDescriptor,
                                                          directoryName2)
    print('Node Id of the second directory: ', directoryNodeId1, sep='')

    nestedDirectoryName = 'MyDirectory3-' + str(random.randint(0, 999_999_999))
    print("Creating nested directory, '", nestedDirectoryName, "'...", sep='')
    # Note how directoryNodeId2 (a parent directory) is passed as the 2nd argument to the CreateDirectory method.
    nestedDirectoryNodeId = fileTransferClient.CreateDirectory(endpointDescriptor,
                                                               UANodeDescriptor(directoryNodeId2),
                                                               nestedDirectoryName)
    print('Node Id of the nested directory: ', nestedDirectoryNodeId, sep='')

    # At this moment, the directory structure we have created looks like this:
    # * MyDirectory1
    # * MyDirectory2
    # * * MyDirectory3

    print('Deleting the first directory...')
    IEasyUAFileTransferExtension.DeleteDirectory(fileTransferClient,
                                                 endpointDescriptor, fileSystemNodeDescriptor, directoryName1)

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

print()
print('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

Reference

IEasyUAFileTransfer Interface
IEasyUAFileTransfer Members
CreateFile Method
Delete Method
CreateDirectory(IEasyUAFileTransfer,UAEndpointDescriptor,UANamedNodePath,String) Method
FindOrCreateAllDirectories(IEasyUAFileTransfer,UAEndpointDescriptor,UANamedNodePath) Method
FindOrCreateDirectory Method

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