QuickOPC User's Guide and Reference
ReadAllText(IEasyUAFileTransfer,UAEndpointDescriptor,UANamedNodeDescriptor,Encoding) Method



OpcLabs.EasyOpcUA Assembly > OpcLabs.EasyOpc.UA.IO.Extensions Namespace > IEasyUAFileTransferExtension2 Class > ReadAllText Method : ReadAllText(IEasyUAFileTransfer,UAEndpointDescriptor,UANamedNodeDescriptor,Encoding) 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.
The character encoding to use.
Returns the contents of an OPC UA text file as a System.String.
Syntax
'Declaration
 
<ExtensionAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function ReadAllText( _
   ByVal fileTransfer As IEasyUAFileTransfer, _
   ByVal endpointDescriptor As UAEndpointDescriptor, _
   ByVal fileNamedNodeDescriptor As UANamedNodeDescriptor, _
   ByVal encoding As Encoding _
) As String
'Usage
 
Dim fileTransfer As IEasyUAFileTransfer
Dim endpointDescriptor As UAEndpointDescriptor
Dim fileNamedNodeDescriptor As UANamedNodeDescriptor
Dim encoding As Encoding
Dim value As String
 
value = IEasyUAFileTransferExtension2.ReadAllText(fileTransfer, endpointDescriptor, fileNamedNodeDescriptor, encoding)

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.
encoding
The character encoding to use.

Return Value

System.String 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.ReadAllText 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.

Note: This method allows you to read from a text file. The contents of the file are returned as a string.

The file encoding can be specified if the contents of the file are in an encoding such as ASCII or UTF-8. If you are reading from a file with extended characters, you need to specify the file encoding using the appropriate overload of this method.

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)).

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