lpoptions applied when?

[Michael Sweet]

Pierre Ossman wrote:
> I was wondering at what points the options for a printer are applied?
> 
> Say that you have the following layout:
> 
> 
> Host A        Relay B        Server C
> +----+        +-----+        +------+
> |    | =====> |     | =====> |      | = [Printer]
> +----+        +-----+        +------+
> 
> Is this the way it goes:
> 
> * An application prints a document to cups on Host A.
> 
> * The pstops filter will be applied so that settings from ~/.lpoptions
> and /etc/cups/lpoptions get applied.

Nope, no filtering is done on the client (Host A).

> * The document is sent via IPP to cups on Relay B.
> 
> * pstops is run on Relay B to get settings from /etc/cups/lpoptions.

Nope, no filtering is done on the relay machine.

> * The document is sent via IPP to cups on Server C.
> 
> * pstops is run on Server C to get settings from /etc/cups/lpoptions.

Here we do run pstops, but the /etc/cups/lpoptions on Server C are
NOT used.

> * The document is sent to the printer.
> 
> In this scenario Host A has found the printer via broadcasts from Relay
> B, but in Relay B the printer is added locally to make sure the jobs
> actually pass through it.

What happens is:

     1. User on Host A submits job via lp/lpr, which add any lpoptions
        stuff for the destination queue from ~/.lpoptions and/or
        /etc/cups/lpoptions.

     2. cupsd on Host A passes the job and any options to Relay B.

     3. cupsd on Relay B passes the job and any options to Server C.

     4. cupsd on Server C passes the job and any options to pstops
        and any other filters in the filter chain for the printer.

        pstops -> other-printer-specific-filters -> backend

     5. pstops and any other filters apply the options and do any
        necessary transformations to the print data and pass it on
        to the backend.

     6. The backend sends the print data to the printer.

In short, options are collected on the client and applied on the
server.

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