Data flow through CUPS

[Sebastian James]

1: I'm trying to modify cups a bit to make it more suitable as a print server on an embedded device. I'm going to send data through in small chunks, rather than as complete files, so that these will process through the system and large files won't get stored on the temporary file space.

Initially I thought I would change cups-lpd and some raw input programs to spool data in chunks. The filters in this device simple pass the data through to the backends (parallel and usb). This means that the backend is likely to be passed a portion of a printjob, which it'll spool to the printer. There shouldn't be and difficulties with this, should there, as long as the next portion of the job is spooled fairly soon after?

2: The filenaming convention of cups data files is d00001-001 for the first print job and d00002-001 for the second job and so on. Under what circumstances does the -001 increment to -002? Initially I thought, "oh must be page number" but how are the filters to know or care what the page number of the print job is? I'd very much appreciate a short explanation of how this works.

Kind regards,

Seb James
Hypercube Systems Ltd.