Parameters
- fileTransfer
- The OPC UA file transfer object that will perform the operation.
- endpointDescriptor
- Endpoint descriptor. Identifies the OPC-UA server.
- directoryNodeDescriptor
- Node descriptor of the OPC UA directory.
Exception | Description |
---|---|
System.ArgumentNullException |
A 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. |
This method does not make any OPC UA operation, and does not throw the usual OpcLabs.EasyOpc.UA.OperationModel.UAException. You can therefore always safely use it to obtain the result interface. All OPC UA operations are made later, on the returned object, and also operation-related exceptions are thrown at that time.
A file provider is an abstraction of a file system, with access to its files and directories. Concrete implementations include a file provider for the physical file system (provided by the operating system), file providers for embedded resources, and, as in this case, a file provider for OPC UA File Transfer facility.
The returned file provider object allows only read-only operations on the file system- such as obtaining a read-only file info or directory contents, or setting up change notifications for the changes in the file system. If you need operations that modify the file system or data in its files, you need to obtain the OpcLabs.BaseLib.Extensions.FileProviders.IWritableFileProvider interface instead, by calling the GetWritableFileProvider method.
Accessing OPC UA files and directories over the abstract file provider model (based on Microsoft.Extensions.FileProviders.IFileProvider, Microsoft.Extensions.FileProviders.IFileInfo, OpcLabs.BaseLib.Extensions.FileProviders.IDirectoryContents2 and their "writable" counterparts), which is what this method does, is highly recommended over the other, lower-level methods. Once you obtained the generalized interface in the file provider model, operations on files and directories can be performed using just names and paths, without having to deal with OPC UA nodes and references.