Many thanks for your help.
Could you clarify Step3 & 4 (refer as below Raja's post) since 'strlen' is not working for xstring (rawstring)?
And how to reverse the 'CONCATENATE' process to store xstring to itab ? Rawstring seems take maximum length of 10,880 char and we have to compress our big file at first.
Have a nice weekend!
Here is the step by step approach.
1. read the raw string from the table.
2. unzip using
CALL METHOD cl_abap_gzip=>decompress_binary EXPORTING gzip_in = <compressed binary string > IMPORTING raw_out = <decompressed binary string>.
3. find the length of the xstring - strlen( <variable> )
4. move the decomressed xstring to a itab
5. use GUI_download , passing file size and setting the file type to BIN
Hope this helps.