Parameters
- fileTransfer
- The OPC UA file transfer object that will perform the operation.
- endpointDescriptor
- Endpoint descriptor. Identifies the OPC-UA server.
- directoryNamedNodePath
- A named node path 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.
If the directory does not exist, an exception is not thrown until the first time a property is accessed or a method is called on the returned object.
The returned writable directory content object allows operations that modify the directory or the file system. If you do not perform such operations and only need read-only operations, such as test for its existence, and enumeration of child files and directories, it is recommended that obtain the OpcLabs.BaseLib.Extensions.FileProviders.IDirectoryContents2 interface instead, by calling the GetDirectoryContents2(IEasyUAFileTransfer,UAEndpointDescriptor,UANamedNodePath) method. This way, you will be protected against calling a method that makes some modifications accidentally.
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.