OPC Studio User's Guide and Reference
ReadAllBytes(IEasyUAFileTransfer,UAEndpointDescriptor,UANamedNodeDescriptor) Method
Example 



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OpcLabs.EasyOpcUA Assembly > OpcLabs.EasyOpc.UA.IO.Extensions Namespace > IEasyUAFileTransferExtension2 Class > ReadAllBytes Method : ReadAllBytes(IEasyUAFileTransfer,UAEndpointDescriptor,UANamedNodeDescriptor) Method
The OPC UA file transfer object that will perform the operation.
Endpoint descriptor. Identifies the OPC-UA server.
The named node descriptor of the file whose contents should be read.
Returns the contents of an OPC UA file as a byte array.
Syntax
'Declaration
 
<ExtensionAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function ReadAllBytes( _
   ByVal fileTransfer As IEasyUAFileTransfer, _
   ByVal endpointDescriptor As UAEndpointDescriptor, _
   ByVal fileNamedNodeDescriptor As UANamedNodeDescriptor _
) As Byte()
 
'Usage
 
Dim fileTransfer As IEasyUAFileTransfer
Dim endpointDescriptor As UAEndpointDescriptor
Dim fileNamedNodeDescriptor As UANamedNodeDescriptor
Dim value() As Byte
 
value = IEasyUAFileTransferExtension2.ReadAllBytes(fileTransfer, endpointDescriptor, fileNamedNodeDescriptor)

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
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.

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.

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.

Remarks

This method is similar to FileSystem.ReadAllBytes Method for normal (operating system) files.

CAUTION: This method does not throw the usual OpcLabs.EasyOpc.UA.OperationModel.UAException. Instead, an System.IO.IOException is thrown in case of an error during the operation.

This method allows you to read from a binary file. The contents of the file are returned as a byte array.

See OPC UA File Transfer internals for information about Stream buffering.

Recommendation: Whenever possible, do not use this method directly, and use a higher-level abstraction instead. You can obtain a file provider (using GetFileProvider2), and make use of its methods, and methods available on the directory contents (obtained using Microsoft.Extensions.FileProviders.IFileProvider.GetDirectoryContents(System.String)) or file info (obtained using Microsoft.Extensions.FileProviders.IFileProvider.GetFileInfo(System.String)).

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...");
        }
    }
}
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