@GODZE We are generating txt and xlsx files. We are writing 1 record at a time using connect-file and doing this in batch to append data to the same file several times in a day. Each day we produce new file. We did explore File Data sets but it is supporting CSV and JSON formats only.
We tried Repository API's as Pega suggested but still have the challenge of encoding in UTF-8 & UTF-16 as well as dealing with large volumes of data.