ReadAllText(IEasyUAFileTransfer,UAEndpointDescriptor,UANamedNodeDescriptor) Method

Endpoint descriptor. Identifies the OPC-UA server.

Because the OpcLabs.EasyOpc.UA.UAEndpointDescriptor has implicit conversions from System.String and System.Uri, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a string (representing the endpoint URL, or a so-called OPC UA endpoint descriptor string), or a System.Uri object, in place of this parameter, and the corresponding endpoint descriptor will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can use the OpcLabs.EasyOpc.UA.UAEndpointDescriptor.FromString or OpcLabs.EasyOpc.UA.UAEndpointDescriptor.FromUri static method instead.

If you are using OPC Wizard (for server development), an implicit conversion from OpcLabs.EasyOpc.UA.EasyUAServerCore can be used in the same way to simply pass the server object in place of this parameter, which will use its OpcLabs.EasyOpc.UA.EasyUAServerCore.EffectiveServerDescriptor property for the connection.

The value of this parameter cannot be null (Nothing in Visual Basic).

Returns the contents of an OPC UA text file as a System.String, using the UTF-8 encoding.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
<ExtensionAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function ReadAllText( _
   ByVal fileTransfer As IEasyUAFileTransfer, _
   ByVal endpointDescriptor As UAEndpointDescriptor, _
   ByVal fileNamedNodeDescriptor As UANamedNodeDescriptor _
) As String

'Usage
 
Dim fileTransfer As IEasyUAFileTransfer
Dim endpointDescriptor As UAEndpointDescriptor
Dim fileNamedNodeDescriptor As UANamedNodeDescriptor
Dim value As String
 
value = IEasyUAFileTransferExtension2.ReadAllText(fileTransfer, endpointDescriptor, fileNamedNodeDescriptor)

[Extension()]
[NotNull()]
public static string ReadAllText( 
   IEasyUAFileTransfer fileTransfer,
   UAEndpointDescriptor endpointDescriptor,
   UANamedNodeDescriptor fileNamedNodeDescriptor
)

[Extension()]
[NotNull()]
public:
static String^ ReadAllText( 
   IEasyUAFileTransfer^ fileTransfer,
   UAEndpointDescriptor^ endpointDescriptor,
   UANamedNodeDescriptor^ fileNamedNodeDescriptor
)

Parameters

fileTransfer

The OPC UA file transfer object that will perform the operation.

This is typically the OpcLabs.EasyOpc.UA.FileTransfer.EasyUAFileTransferClient object.

The value of this parameter cannot be null (Nothing in Visual Basic).

endpointDescriptor

Endpoint descriptor. Identifies the OPC-UA server.

The value of this parameter cannot be null (Nothing in Visual Basic).

fileNamedNodeDescriptor

The named node descriptor of the file whose contents should be read.

Because the OpcLabs.EasyOpc.UA.Navigation.UANamedNodeDescriptor has an implicit conversion from OpcLabs.EasyOpc.UA.UANodeDescriptor, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a OpcLabs.EasyOpc.UA.UANodeDescriptor (containing the final node descriptor) in place of this parameter, and the corresponding OPC UA named node descriptor will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can use the OpcLabs.EasyOpc.UA.Navigation.UANamedNodeDescriptor.FromUANodeDescriptor static method instead.

The value of this parameter cannot be null (Nothing in Visual Basic).

Return Value

System.String containing the contents of the file.

This method never returns null (Nothing in Visual Basic).

Exceptions

Exception Description

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.

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.

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)).

This is an extension method (info: C#, VB.NET). In languages that have support for extensions methods (such as C# and VB.NET), you can use the extension method as if it were a regular method on the object that is its first parameter. In other languages (such as with Python.NET), you will call the extension as a static method, and pass it the object on which it acts as its first parameter.

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

IEasyUAFileTransferExtension2 Class
IEasyUAFileTransferExtension2 Members
Overload List
ReadAllText(IFileInfo) Method
ReadAllBytes(IEasyUAFileTransfer,UAEndpointDescriptor,UANamedNodeDescriptor) Method
WriteAllText(IEasyUAFileTransfer,UAEndpointDescriptor,UANamedNodeDescriptor,String) Method

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