Hardware support architecture for remote Clients

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Hi!

Sorry for probably dumb/beginner question. I read manual, 
but partly by language problems and lack of experience it 
was not clear to me about the hardware support for remote 
clients.

Let's say we have central server where the LedgerSMB 
resides and have remote clients:

How the printer jobs is sent to printer (if it is not HTML 
print)?
How the card / bar code readers send their requests/posts 
to the server?

Are there some software with them?
etc.?

brgds & Thanks in advance,
Janeks