Subject: IPP> MOD - towards conformance/simplification

From: Tom Hastings <[email-masked]>
Date: Fri, 21 Mar 1997 08:27:46 PST

Here are two proposals for simplification of the Model and for 
actually specifying some conformance (which is where the rubber
hits the road in determining what has to be implemented).

1. Lets make a pass through the document and see which attributes
we can make "conditionally mandatory" to use the SNMP parlance.

A conditionally mandatory attribute need not be implemented if the
implementation does not have the feature that the attribute controls.

For example, a simplex printer need not implement the sides attribute
and a printer that has no finishing need not implement the finishing
and a Printer that cannot do multiple copies from a single document
need not implement the copies attribute.  A Printer that does not
allow the administrator to specify supported values need only implement
the values that are ready (like the Printer MIB).  A Printer with a single
input tray and no means to request the operator to switch the media need
not implement the media attribute.  etc. etc.

Thus an IPP Printer embedded in a simple desktop printer would not have
to deal with many of the attributes in the Model.  It would not have
to return them at all in a Get Attributes or a Get Jobs Response.
The Printer would ignore them if submitted in a Print request.

A client either is a driver for that particualar printer and so will not
send any attributes that the Printer doesn't implement or the client should
first request the job template from the Printer and get only the attributes
that that Printer implements.

2. Lets make ALL adornments conditionally mandatory.

a. I believe that we have chosen the adornments, so that the simplest 
implementation is without any adornments.  

b. A conforming Printer shall ignore any adornments it doesn't understand.  

c. Also adorments are keywords that can be added to after the standard 
is done through type 2 keyword registration with the PWG and IANA.

I agree with Bob that we don't need to actually agree on the above 
simplification before publishing our internet draft, but I wanted to
give heart to those who think what we have is too complicated for
Printers embedded in a simple desktop output device (one, but not our 
only, goal).

So we could just list them as Issues for now.

Tom

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From: [email-masked] (Robert Herriot)
Date: Fri, 21 Mar 1997 18:32:14 -0800

>From [email-masked] Fri Mar 21 08:31:18 1997

> not implement the media attribute.  etc. etc.

But what should a printer with no duplexing and no finishing do when it
receives a job which has sides set to 1-sided and finishing set to
none.  Shouldn't that printer at least know enough about the standard
attributes to realize that it supports those two values?

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From: JK Martin <[email-masked]>
Date: Sat, 22 Mar 1997 15:38:07 -0500 (EST)

Bob,

Once again you've hit the proverbial nail on the head.

It never ceases to amaze me how some people insist on saying things
like "Well, if that's too complex, you don't have to implement it."

What do they mean when they say "You don't have to implement it"???
Do they mean you can just simply IGNORE the situation (whether it
be an attribute setting, or protocol operation, or whatever)?

To answer your question, OF COURSE the printer must know enough
about the standard to handle those attributes.  A similar question
arose during yesterday's telecon in which the group responded with
a consensual "NO" when asked whether an IPP Printer implementation
can simply ignore attribute values it chooses to "not implement".

	...jay

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>From [email-masked] Fri Mar 21 21:37 EST 1997
Date: Fri, 21 Mar 1997 18:32:14 -0800
From: [email-masked] (Robert Herriot)
To: [email-masked], [email-masked]
Subject: Re: IPP> MOD - towards conformance/simplification

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