Create Method (IWritableDirectoryContents)

Creates a directory.

Syntax

void Create()

void Create();

'Declaration
 
Sub Create()

'Usage
 
Dim instance As IWritableDirectoryContents
 
instance.Create()

Exceptions

Exception	Description
System.IO.IOException	An I/O error has occurred. 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.NotSupportedException	An invoked method is not supported at all, or is not supported with the parameters used to create the object.
System.Security.SecurityException	A security error was detected. 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.UnauthorizedAccessException	The operating system has denied access because of an I/O error or a specific type of security error. 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 is similar in purpose to System.IO.DirectoryInfo.Create, but is generalized for any kind of writable directory contents, not just files in the physical file system.

If the directory already exists, this method does nothing.

If the directory is created by this method, it initially contains no files.

Example

.NET

// Shows how to create and delete OPC UA directories, using the file provider model.

using System;
using OpcLabs.BaseLib.Extensions.FileProviders;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.Extensions;
using OpcLabs.EasyOpc.UA.FileTransfer;

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

            // A node that represents an OPC UA file system (a root directory).
            UANodeDescriptor fileSystemNodeDescriptor = "nsu=http://www.unifiedautomation.com/DemoServer/ ;s=Demo.Files.FileSystem";

            // 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();

            Console.WriteLine("Getting writable file provider...");
            IWritableFileProvider writableFileProvider =
                fileTransferClient.GetWritableFileProvider(endpointDescriptor, fileSystemNodeDescriptor);
            // From this point onwards, the code is independent of the concrete realization of the file provider, and would
            // be identical e.g. for files in the physical file system, if the corresponding file provider was used.

            // Create two directories, and one nested directory, and delete the first one.
            try
            {
                string directoryName1 = "MyDirectory1-" + random.Next();
                Console.WriteLine($"Creating first directory, '{directoryName1}'...");
                IWritableDirectoryContents writableDirectoryContents1 = writableFileProvider.GetWritableDirectoryContents(directoryName1);
                writableDirectoryContents1.Create();

                string directoryName2 = "MyDirectory2-" + random.Next();
                Console.WriteLine($"Creating second directory, '{directoryName2}'...");
                IWritableDirectoryContents writableDirectoryContents2 = writableFileProvider.GetWritableDirectoryContents(directoryName2);
                writableDirectoryContents2.Create();

                string nestedDirectoryName = "MyDirectory3-" + random.Next();
                Console.WriteLine($"Creating nested directory, '{nestedDirectoryName}'...");
                writableDirectoryContents2.CreateSubdirectory(nestedDirectoryName);

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

                Console.WriteLine("Deleting the first directory...");
                writableDirectoryContents1.Delete();
            }
            // Methods in the file provider model throw IOException and other exceptions, but not UAException.
            catch (Exception exception)
            {
                Console.WriteLine($"*** Failure: {exception.GetBaseException().Message}");
                return;
            }

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

# Shows how to create and delete OPC UA directories, using the file provider model.

# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc
import random

# Import .NET namespaces.
from System import *
from OpcLabs.BaseLib.Extensions.FileProviders import *
from OpcLabs.EasyOpc.UA import *
from OpcLabs.EasyOpc.UA.Extensions import *
from OpcLabs.EasyOpc.UA.FileTransfer import *


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

# A node that represents an OPC UA file system (a root directory).
fileSystemNodeDescriptor = UANodeDescriptor('nsu=http://www.unifiedautomation.com/DemoServer/ ;s=Demo.Files.FileSystem')

# 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)

print('Getting writable file provider...')
writableFileProvider = IEasyUAFileTransferExtension.GetWritableFileProvider(fileTransferClient,
                                                                            endpointDescriptor,
                                                                            fileSystemNodeDescriptor)
# From this point onwards, the code is independent of the concrete realization of the file provider, and would
# be identical e.g. for files in the physical file system, if the corresponding file provider was used.

# Create two directories, and one nested directory, and delete the first one.
try:
    directoryName1 = 'MyDirectory1-' + str(random.randint(0, 999_999_999))
    print("Creating first directory, '", directoryName1, "'...", sep='')
    writableDirectoryContents1 = writableFileProvider.GetWritableDirectoryContents(directoryName1)
    writableDirectoryContents1.Create()

    directoryName2 = 'MyDirectory2-' + str(random.randint(0, 999_999_999))
    print("Creating second directory, '", directoryName2, "'...", sep='')
    writableDirectoryContents2 = writableFileProvider.GetWritableDirectoryContents(directoryName2)
    writableDirectoryContents2.Create()

    nestedDirectoryName = 'MyDirectory3-' + str(random.randint(0, 999_999_999))
    print("Creating nested directory, '", nestedDirectoryName, "'...", sep='')
    IWritableDirectoryContentsExtension.CreateSubdirectory(writableDirectoryContents2, nestedDirectoryName)

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

    print('Deleting the first directory...')
    IWritableDirectoryContentsExtension.Delete(writableDirectoryContents1)

# Methods in the file provider model throw IOException and other exceptions, but not UAException.
except Exception as exception:
    print('*** Failure: ' + exception.GetBaseException().Message)
    exit()

print()
print('Finished.')

' Shows how to create and delete OPC UA directories, using the file provider model.

Imports OpcLabs.BaseLib.Extensions.FileProviders
Imports OpcLabs.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.Extensions
Imports OpcLabs.EasyOpc.UA.FileTransfer

Namespace FileProviders._WritableDirectoryContents

    Friend Class CreateAndDelete

        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")

            ' A node that represents an OPC UA file system (a root directory).
            Dim fileSystemNodeDescriptor As UANodeDescriptor =
                "nsu=http://www.unifiedautomation.com/DemoServer/ ;s=Demo.Files.FileSystem"

            ' 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

            Console.WriteLine("Getting writable file provider...")
            Dim writableFileProvider As IWritableFileProvider =
                fileTransferClient.GetWritableFileProvider(endpointDescriptor, fileSystemNodeDescriptor)
            ' From this point onwards, the code is independent of the concrete realization of the file provider, and would
            ' be identical e.g. for files in the physical file system, if the corresponding file provider was used.

            ' Create two directories, and one nested directory, and delete the first one.
            Try
                Dim directoryName1 As String = "MyDirectory1-" & random.Next()
                Console.WriteLine($"Creating first directory, '{directoryName1}'...")
                Dim writableDirectoryContents1 As IWritableDirectoryContents = writableFileProvider.GetWritableDirectoryContents(directoryName1)
                writableDirectoryContents1.Create()

                Dim directoryName2 As String = "directoryName2-" & random.Next()
                Console.WriteLine($"Creating second directory, '{directoryName2}'...")
                Dim writableDirectoryContents2 As IWritableDirectoryContents = writableFileProvider.GetWritableDirectoryContents(directoryName2)
                writableDirectoryContents2.Create()

                Dim nestedDirectoryName As String = "MyDirectory3-" & random.Next()
                Console.WriteLine($"Creating nested directory, '{nestedDirectoryName}'...")
                writableDirectoryContents2.CreateSubdirectory(nestedDirectoryName)

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

                Console.WriteLine("Deleting the first directory...")
                writableDirectoryContents1.Delete()

                ' Methods in the file provider model throw IOException and other exceptions, but not UAException.
            Catch exception As Exception
                Console.WriteLine("*** Failure: {0}", exception.GetBaseException.Message)
                Exit Sub
            End Try

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

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

IWritableDirectoryContents Interface
IWritableDirectoryContents Members
CreateSubdirectory Method
Delete Method

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