cups cupsBackChannelRead

[velupillai]

i wrote a port monitor and now i get the status.
thank you very much.
> velupillai wrote:
> >> velupillai wrote:
> >>> Hello,
> >>>
> >>> Thanks for your response.
> >>> It is the standard usb backend which is used.
> >>> We are working for the manufacturer of the USB Printer.
> >>> We have developed driver (The printing is working -- But we cannot receive the status)
> >>> To Get the status we have to send a request. We do that directly in the data flow.
> >>> The Printer sends a response (one byte) which is received by the backEnd
> >>> (trace "Received 1 bytes of back-channel data!")
> >>> We see in the sources that the Backend call "CupsBackchannelWrite"
> >>> (this function write in fd=3)
> >>>
> >>> In our process (ijsserver) we try to get the status Byte by calling
> >>> cupsBackChannelRead
> >>> _bytes = cupsBackChannelRead(_buffer,1, 0.0)) which return -1
> >> You can't read back-channel data from an IJS-based printer driver.
> >> You MUST use CUPS raster, as IJS does not pass the back (or side)
> >> channel file descriptors to the driver...
> >>
> >
> > So How can we get the printer status ?
> > The backend receive the response (we verified it's the good one)
> > Now what can we do ?
> > Our IJS Server is already operational and delivered to our client.
>
> You could do a port monitor, which is a separate filter between
> your driver and the backend, but longer term you really want to
> do a CUPS raster driver.  IJS requires Ghostscript, which kills it
> as a solution systems without it (e.g. Mac OS X).
>
> --
> ______________________________________________________________________
> Michael Sweet, Easy Software Products           mike at easysw dot com