CUPS 1.2 and bidirectional communications

Michael Sweet mike at easysw.com
Thu Jun 16 11:16:55 PDT 2005


Vladimir Buzuev wrote:
> More information:
> 
> I need another sort of filter works between my ordinal raster filter
> and the backend. The filter should be able to request some
> information from the printer, like a status, and based on that do
> some additional processing of sending data. Is it possible? How to
> read information returned by the printer?

In the (nearish) future, we will have the backchannel API stuff
committed to the repo (and thus be part of a future snapshot) which
will allow you to safely read backchannel data with a timeout, such
that your filter will not hang when printing through an interface
that does not support backchannel data (i.e. anything except socket,
usb, serial, and in some cases parallel)

Right now you just have to read from file descriptor 3 to get the
backchannel data.

-- 
______________________________________________________________________
Michael Sweet, Easy Software Products           mike at easysw dot com
Internet Printing and Document Software          http://www.easysw.com




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