[cups.development] Bi-di in cups1.2 ?

[Emmanuel Briand]

Hi,
I need to achieve bidirectional communications with ticket printers and IPP
(CUPS)  is studied as a candidate.
I understood  that some data can be get back from jobs (with
get-job-attributes requests) if the backend write it to stderr (?).
But with this mechanism, you are not sure to get all the messages sent by
the printer.

It seems that a bi-di API is studied by PWG and that backchanneling is
planned in cups 1.2.
Questions :
Is this bi-di API and backchanneling are the same thing ?
>From a quick look in cups 1.2 sources, it seems that backchanneling is far
from being implemented, am I right ?
Since my company is interested in Open Source, is there a way to contribute
?

Thanks for any response/comments,
Emmanuel