title_body: Sending data automatically to a server from a PDF document
upvoted_answer: Answer:
  the easiest way is to add URL-links in the PDF text, because is the unique widespread (standard) option to online interactivity, present in near all PDF-readers. Some variations: 1) a link to a complete online form webpage; 2) one link for each question/answer.
  
  Comment: why to use PDF? and about EPUB?. EPUB is HTML, so have standard support to HTML interactivity.