IPP> notification methods

IPP> notification methods

IPP> notification methods

pmoore at peerless.com pmoore at peerless.com
Fri Jul 21 12:20:54 EDT 2000

So are we agreed that mandating a machine readable form is needed - Yes? I mean
that if a device does a machine readble method it MUST do at least INDP.

Michael Sweet <mike at easysw.com> on 07/21/2000 08:48:58 AM

To:   pmoore at peerless.com
cc:   ipp at pwg.org (bcc: Paul Moore/AUCO/US)

Subject:  Re: IPP> notification methods

pmoore at peerless.com wrote:
> 1.mailto and indp are used by clients for totally different
> purposes - you can do things with indp that you absolutely cannot
> do with mailto and vice versa. They are not overlapping they are
> complimentary. Therefore there is no bloat issue as such

I didn't say mailto and indp would cause bloat - in fact I agree
with you.

However, if the PWG does not mandate one or more required methods
then a client will be required to support them *all*, which will
cause bloat.  Requiring a minimum level of notification support
(including one or two required methods) will prevent this from

> ...
> 3. I am surprised that CUPS would want to use mailto from the
> actual printer back to the cups end user. I would have thought

Nope, that's not what we would do.

For our IPP backend we'd probably use indp or polling.

> ...
> 4. even if we mandate mailto, not all printers will support it. In
> order for it to work the printer must have its SMTP gateway
> configured by somebody. In some cases this will not have been done
> so the mailto method wont work - interesting question about how a
> printer should deal with this case. Presumably it must not say it
> can do mailto - or perhaps it will accept the requests and throw
> them away. Clients will always have to be smart.

This is an interesting point - it would be easy to return an error
from a create-subscription operation, but what would we return from
a print-job or create-job?

> ...
> 7.Mandating a method does not gurantee interop. THe two methods do
> totally different things. If my client needs machine readable
> notifications (for example I have a rendering pipeline driven by
> page complete messages) then telling me that mailto is available
> does nothing to help me. Its like saying "we have mandated SMTP why
> the heck do you want to do HTTP" - they do different things.

I'm not suggesting that mandating email alone will be sufficient;
likely we need to mandate at least one machine-readable method as
well.  However, in practical terms email is the method that will
gain IPP the most visibility and acceptance, with the other
methods being supported as demand grows.

Michael Sweet, Easy Software Products                  mike at easysw.com
Printing Software for UNIX                       http://www.easysw.com

More information about the Ipp mailing list