Hands a piece of file data to the application.
func onWriteFile(connectionID: Int64, operationStatus: inout Int32)
The class fires this event repeatedly during an overridden upload operation to pass file data to the application.
The handler of this event should retrieve the pending data buffer with a GetClientBuffer call, and write it to the end of the file that is being uploaded.
Use the OperationStatus parameter to return the operation result back to the server.
Set OperationStatus to one of the following values: