Overall design of enabling external Cups filter

[Andreas Bohne-Lang]

I would like to ask for a good strategy to enable external cups filter and how to embed them with minimal costs. While programming a filter during the last days I noticed that cups can handle external filter but there is no real hook to embed them.

Wish: A chain that works on the postscript files passed by the cups postscript chain - coming with the mime-type: application/vnd.cups-postscript

How to enable external filters?:

Case 1) Cups design part a

* Edit the PPD-File and set the *cupsFilter to a new final mime-type
* Edit the mime.conv and add your new mime-type
* Edit the mime.type and add your new mime-type (application/accounting)

EG: Your new filter is accounting then your mime.conv is
application/postscript  application/vnd.cups-postscript 33 pstops
application/vnd.cups-postscript  application/accounting 33 accounting

and you have to add this to the PPD file.

All in all you need to edit 3 cups files



Case 2) Cups design part b
* Edit the mime.conv and add your new mime-type in the chain
* Edit the mime.type and add your new mime-type (o-ps)

EG: Your new filter is accounting then your mime.conv is
application/postscript  application/o-ps        33 pstops
application/o-ps        application/vnd.cups-postscript 33 accounting

You do not need to edit the PPD file.

All in all you need to edit 2 cups files


Case 3) A skript chain within the cups chain
I programmed a filter that can call other filter - one after each other.
Thus I have a chain within a chain.

* Edit the mime.conv and replace the filter at postscript
application/postscript  application/vnd.cups-postscript  33 mychain

All in all you need to edit 1 cups files

Case 4) (Theoretical - as far as I know)
* Edit the mime.conv and add  your filter

EG: Your new filter is accounting then your mime.conv is
application/postscript  application/vnd.cups-postscript 33 pstops
application/postscript  application/vnd.cups-postscript 22 accounting

The could be more than one filter for each mime-type and the order of calling the different filters is set by the cost.


My question: Which will bes the way cups go on the day after tomorrow?
Which way is recommended?

Greetings -- Andreas