Returns the contents of an OPC UA file as a byte array.
Syntax
Parameters
- fileTransfer
- The OPC UA file transfer object that will perform the operation.
- endpointDescriptor
- Endpoint descriptor. Identifies the OPC-UA server.
- fileNamedNodeDescriptor
- The named node descriptor of the file whose contents should be read.
Return Value
System.Byte array containing the contents of the file.
Exceptions
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. |
System.IO.FileNotFoundException |
An attempt to access a file that does not exist on disk has failed.
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.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. |
Example
.NET
// Shows how to read the full contents of an OPC UA file at once, 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 .
using System;
using System.IO;
using System.Text;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.FileTransfer;
using OpcLabs.EasyOpc.UA.IO.Extensions;
namespace UADocExamples.FileTransfer._EasyUAFileTransferClient
{
class ReadAllBytes
{
public static void Main1()
{
// Unified Automation .NET based demo server (UaNETServer/UaServerNET.exe)
UAEndpointDescriptor endpointDescriptor = "opc.tcp://localhost:48030";
// A node that represents an instance of OPC UA FileType object.
UANodeDescriptor fileNodeDescriptor = "nsu=http://www.unifiedautomation.com/DemoServer/ ;s=Demo.Files.TextFile";
// Instantiate the file transfer client object
var fileTransferClient = new EasyUAFileTransferClient();
// Read in all contents from a specified file node.
byte[] bytes;
try
{
Console.WriteLine("Reading the whole file...");
bytes = fileTransferClient.ReadAllBytes(endpointDescriptor, fileNodeDescriptor);
}
// Beware that ReadAllFileBytes throws IOException and not UAException.
catch (IOException ioException)
{
Console.WriteLine("*** Failure: {0}", ioException.GetBaseException().Message);
return;
}
// Display result
Console.WriteLine();
// We know that the file contains text, so we convert the received data to a string. If the file contents was
// binary, you would process the data according to their format.
string text = Encoding.UTF8.GetString(bytes);
Console.WriteLine("File content:");
Console.WriteLine(text);
Console.WriteLine();
Console.WriteLine("Finished...");
}
}
}
# Shows how to read the full contents of an OPC UA file at once, 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 .
# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc
# Import .NET namespaces.
from System.Text import *
from OpcLabs.EasyOpc.UA import *
from OpcLabs.EasyOpc.UA.FileTransfer import *
from OpcLabs.EasyOpc.UA.IO.Extensions import *
from OpcLabs.EasyOpc.UA.Navigation import *
# Unified Automation .NET based demo server (UaNETServer/UaServerNET.exe).
endpointDescriptor = UAEndpointDescriptor('opc.tcp://localhost:48030')
# A node that represents an instance of OPC UA FileType object.
fileNodeDescriptor = UANodeDescriptor('nsu=http://www.unifiedautomation.com/DemoServer/ ;s=Demo.Files.TextFile')
# Instantiate the file transfer client object.
fileTransferClient = EasyUAFileTransferClient()
# Read in all contents from a specified file node.
try:
print('Reading the whole file...')
bytes = IEasyUAFileTransferExtension2.ReadAllBytes(fileTransferClient,
endpointDescriptor,
UANamedNodeDescriptor(fileNodeDescriptor))
# Beware that ReadAllFileBytes throws IOException and not UAException.
except IOException as ioException:
print('*** Failure: ' + ioException.GetBaseException().Message)
exit()
# Display result.
print()
# We know that the file contains text, so we convert the received data to a string. If the file contents was
# binary, you would process the data according to their format.
text = Encoding.UTF8.GetString(bytes)
print('File content:')
print(text)
print()
print('Finished.')
' Shows how to read the full contents of an OPC UA file at once, 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 .
Imports System.IO
Imports System.Text
Imports OpcLabs.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.FileTransfer
Imports OpcLabs.EasyOpc.UA.IO.Extensions
Namespace FileTransfer._EasyUAFileTransferClient
Friend Class ReadAllBytes
Public Shared Sub Main1()
' Unified Automation .NET based demo server (UaNETServer/UaServerNET.exe)
Dim endpointDescriptor As UAEndpointDescriptor = "opc.tcp://localhost:48030"
' A node that represents an instance of OPC UA FileType object.
Dim fileNodeDescriptor As UANodeDescriptor = "nsu=http://www.unifiedautomation.com/DemoServer/ ;s=Demo.Files.TextFile"
' Instantiate the file transfer client object
Dim fileTransferClient = New EasyUAFileTransferClient
' Read in all contents from a specified file node.
Dim bytes As Byte()
Try
Console.WriteLine("Reading the whole file...")
bytes = fileTransferClient.ReadAllBytes(endpointDescriptor, fileNodeDescriptor)
' Beware that ReadAllFileBytes throws IOException And Not UAException.
Catch ioException As IOException
Console.WriteLine("*** Failure: {0}", ioException.GetBaseException.Message)
Exit Sub
End Try
' Display result
Console.WriteLine()
' We know that the file contains text, so we convert the received data to a string. If the file contents was
' binary, you would process the data according to their format.
Dim text As String = Encoding.UTF8.GetString(bytes)
Console.WriteLine("File content:")
Console.WriteLine(text)
Console.WriteLine()
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