Return binary data via RFC

I want to return binary data in ABAP, for example a PNG image file.

Which data type should I use? string, xstring, ...?

I use the PyRFC SDK: https://github.com/SAP/PyRFC

xstring

Sidenotes if you have large data:

• max size of an xstring is 2GB (depending also on profile parameter ztta/max_memreq_MB)
• If you use an internal table of xstrings (e.g. dictionary type XSTRINGS_TABLE), dynamic memory allocation is easier because it will not be requested in one go, as is the case for a flat xstring