How to submit a PDF document to spool request by coding

Hi experts,

I have a pdf document that is stored somewhere in SAP system, for example MIME repository. So I can read this PDF document and get its content as an xstring.

I know SAP can print a smartform directly by calling its function module, or submit a program (list output) to SAP-SPOOL to generate a spool request.

But how can I submit a document or an xstring which presents the content of a document to spool request in order to print it out?

Or should I do it in some other way?

Any of the suggestion or hint will be help.

Thanks!