Hi John,
I don't like using the 'hash-based' approach, because it completely
sacrifices human readability (the whole benefit of CONNEG, in my
opinion).
I think we should explore the possibility of explicitly excluding
'resolution' and a few other frequent variables from our base
CONNEG profiles.
Otherwise, yes I'd prefer to return to full CONNEG expressions with
all variables.
Cheers,
- Ira McDonald
High North Inc
-----Original Message-----
From: John Pulera [mailto:jpulera@minolta-mil.com]
Sent: Tuesday, January 29, 2002 7:25 PM
To: IPP-Fax Group
Subject: IFX> Using CONNEG with IPPFAX
Per my action item from the last meeting, I checked with Graham Klyne (main
author of the CONNEG-related RFCs) on the syntactical validity of section
A.1.2 and its subsections in the UIF Specification. Although we'll be able
to define "auxiliary predicate" values (e.g., "profile-uif-f" or
"profile-uif-cg"), we won't be able to use them to add on incremental
features like the following:
(| (profile-uif-s)
(& (profile-uif-f])
(dpi=[200,300,600,1200]) )
(& (profile-uif-c)
(dpi=[200,300,600]) ) )
to indicate optional support of 1200 dpi for UIF Profile F and optional 600
dpi for UIF Profile C. He made a couple of suggestions:
(1) If the goal is to shorten the length of the CONNEG expression, then he
suggested we use the hash-based approach described in RFC2938 (for which
there is a freely available Java implementation at the IMC website:
http://www.imc.org/ietf-medfree/index.html). The disadvantage here, however,
is capabilities advertised in the CONNEG expressions would no longer be
"human-readable". See some examples here:
(2) If human readability is desired, then, alternatively, we can exclude
frequently varied parameters (e.g., resolution) from the minimum CONNEG
strings specified in section A.1.2.1 of the UIF spec. If we did this, then
the CONNEG expression shown earlier would be valid. But, in this case, how
many parameters should be excluded from the minimum CONNEG strings &
separately specified in the CONNEG expression? Where would we draw the line?
Do I here preferences for either alternatives 1 or 2? Or should we just go
back to using the whole expression since we've already taken into account
really long values for the 'uif-profile-capabilities' IPP attribute by using
1setOf text(MAX)?
Graham Klyne's response is attached.
John P
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