Represents an enumerable contents of a directory, from which files and sub-directories can be obtained.
Syntax
Example
.NET
// Shows how to browse for OPC UA files and 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._DirectoryContents2
{
class Enumerate
{
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 files, and then browse the directory that contains them.
try
{
string fileName1 = "MyFile1-" + random.Next();
Console.WriteLine($"Creating first file, '{fileName1}'...");
IWritableFileInfo writableFileInfo1 = writableFileProvider.GetWritableFileInfo(fileName1);
writableFileInfo1.WriteAllBytes(Array.Empty<byte>());
string fileName2 = "MyFile2-" + random.Next();
Console.WriteLine($"Creating second file, '{fileName2}'...");
IWritableFileInfo writableFileInfo2 = writableFileProvider.GetWritableFileInfo(fileName2);
writableFileInfo2.WriteAllBytes(Array.Empty<byte>());
Console.WriteLine("Browsing for files...");
IDirectoryContents2 directoryContents2 = writableFileProvider.GetDirectoryContents2(null);
foreach (IFileInfo2 fileInfo2 in directoryContents2)
Console.WriteLine(fileInfo2);
// You can distinguish between files and directories using the IFileInfo.IsDirectory property.
}
// 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 browse for OPC UA files and 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 files, and then browse the directory that contains them.
try:
fileName1 = 'MyFile1-' + str(random.randint(0, 999_999_999))
print("Creating first file, '", fileName1, "'...", sep='')
writableFileInfo1 = writableFileProvider.GetWritableFileInfo(fileName1)
IWritableFileInfoExtension.WriteAllBytes(writableFileInfo1, Array.Empty[Byte]())
fileName2 = 'MyFile2-' + str(random.randint(0, 999_999_999))
print("Creating second file, '", fileName2, "'...", sep='')
writableFileInfo2 = writableFileProvider.GetWritableFileInfo(fileName2)
IWritableFileInfoExtension.WriteAllBytes(writableFileInfo2, Array.Empty[Byte]())
print('Browsing for files...')
directoryContents2 = writableFileProvider.GetDirectoryContents2(None)
for fileInfo2 in directoryContents2:
print(fileInfo2)
# You can distinguish between files and directories using the IFileInfo.IsDirectory property.
# 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 browse for OPC UA files and 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._DirectoryContents2
Friend Class Enumerate
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 files, and then browse the directory that contains them.
Try
Dim fileName1 As String = "MyFile1-" & random.Next()
Console.WriteLine($"Creating first file, '{fileName1}'...")
Dim writableFileInfo1 As IWritableFileInfo = writableFileProvider.GetWritableFileInfo(fileName1)
writableFileInfo1.WriteAllBytes(Array.Empty(Of Byte))
Dim fileName2 As String = "MyFile2-" & random.Next()
Console.WriteLine($"Creating second file, '{fileName2}'...")
Dim writableFileInfo2 As IWritableFileInfo = writableFileProvider.GetWritableFileInfo(fileName2)
writableFileInfo2.WriteAllBytes(Array.Empty(Of Byte))
Console.WriteLine("Browsing for files...")
Dim directoryContents2 As IDirectoryContents2 = writableFileProvider.GetDirectoryContents2(Nothing)
For Each fileInfo2 As IFileInfo2 In directoryContents2
Console.WriteLine(fileInfo2)
Next fileInfo2
' You can distinguish between files and directories using the IFileInfo.IsDirectory property.
' 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
See Also
