OPC Studio User's Guide and Reference
CreateStream(IEasyUAFileTransfer,UAEndpointDescriptor,UANamedNodeDescriptor,Int32) Method



OpcLabs.EasyOpcUA Assembly > OpcLabs.EasyOpc.UA.IO.Extensions Namespace > IEasyUAFileTransferExtension2 Class > CreateStream Method : CreateStream(IEasyUAFileTransfer,UAEndpointDescriptor,UANamedNodeDescriptor,Int32) Method
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).

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.

Also, because the OpcLabs.EasyOpc.UA.Discovery.UAApplicationElement and OpcLabs.EasyOpc.UA.Discovery.UADiscoveryElement have an implicit conversion to OpcLabs.EasyOpc.UA.UAEndpointDescriptor, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a OpcLabs.EasyOpc.UA.Discovery.UAApplicationElement or OpcLabs.EasyOpc.UA.Discovery.UADiscoveryElement (results from OPC UA discovery) 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 convert a (non-null) OpcLabs.EasyOpc.UA.Discovery.UAApplicationElement or OpcLabs.EasyOpc.UA.Discovery.UADiscoveryElement to OpcLabs.EasyOpc.UA.UAEndpointDescriptor using the OpcLabs.EasyOpc.UA.Discovery.UAApplicationElement.ToUAEndpointDescriptor or ToUAEndpointDescriptor 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).

The named node descriptor of the file that should be created for the stream.

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).

The buffer size in bytes.

Valid values of this parameter are in the range from 0 to 2147483647 (Int32.MaxValue).

Creates a new OPC UA file and provides a System.IO.Stream to access it for reading/writing, specifying the buffer size.
Syntax
'Declaration
 
<ExtensionAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function CreateStream( _
   ByVal fileTransfer As IEasyUAFileTransfer, _
   ByVal endpointDescriptor As UAEndpointDescriptor, _
   ByVal fileNamedNodeDescriptor As UANamedNodeDescriptor, _
   ByVal bufferSize As Integer _
) As Stream
'Usage
 
Dim fileTransfer As IEasyUAFileTransfer
Dim endpointDescriptor As UAEndpointDescriptor
Dim fileNamedNodeDescriptor As UANamedNodeDescriptor
Dim bufferSize As Integer
Dim value As Stream
 
value = IEasyUAFileTransferExtension2.CreateStream(fileTransfer, endpointDescriptor, fileNamedNodeDescriptor, bufferSize)

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.

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.

Also, because the OpcLabs.EasyOpc.UA.Discovery.UAApplicationElement and OpcLabs.EasyOpc.UA.Discovery.UADiscoveryElement have an implicit conversion to OpcLabs.EasyOpc.UA.UAEndpointDescriptor, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a OpcLabs.EasyOpc.UA.Discovery.UAApplicationElement or OpcLabs.EasyOpc.UA.Discovery.UADiscoveryElement (results from OPC UA discovery) 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 convert a (non-null) OpcLabs.EasyOpc.UA.Discovery.UAApplicationElement or OpcLabs.EasyOpc.UA.Discovery.UADiscoveryElement to OpcLabs.EasyOpc.UA.UAEndpointDescriptor using the OpcLabs.EasyOpc.UA.Discovery.UAApplicationElement.ToUAEndpointDescriptor or ToUAEndpointDescriptor 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).

fileNamedNodeDescriptor
The named node descriptor of the file that should be created for the stream.

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).

bufferSize
The buffer size in bytes.

Valid values of this parameter are in the range from 0 to 2147483647 (Int32.MaxValue).

Return Value

Returns a System.IO.Stream that provides read/write access to the file specified.

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

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.

The value of an argument is outside the allowable range of values as defined by the invoked method.

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 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

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.

For this method to succeed, the fileNamedNodeDescriptor must contain both the named node path (of the parent directory) in the OpcLabs.EasyOpc.UA.Navigation.UANamedNodeDescriptor.NamedNodePath property, and the node name (name of the file) in the OpcLabs.EasyOpc.UA.Navigation.UANamedNodeDescriptor.NodeName property.

A new file will be created. If the file already exists, an System.IO.IOException exception is thrown.

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

Recommendation: Whenever possible, do not use this method directly, and use a higher-level abstraction instead. You can obtain a writable file provider (using GetWritableFileProvider), and make use of its methods, and methods available on the writable directory contents (obtained using OpcLabs.BaseLib.Extensions.FileProviders.IWritableDirectory.GetWritableDirectoryContents) or writable file info (obtained using OpcLabs.BaseLib.Extensions.FileProviders.IWritableDirectory.GetWritableFileInfo).

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

See Also