Subject: RE: [VPIM] Re: draft-ema-vpim-pndn-00.txt

From: "McDonald, Ira" <[email-masked]>
Date: Mon, 24 Jan 2000 21:31:01 -0800

Ned,

With all respect to you and Keith, this recent thread and
both of your remarks below come perilously close to saying
that Quality of Service is entirely subjective and therefore
interoperability testing is a waste of time for Internet
Fax services.  

More thought should go into partial delivery, sure.  But at
the end of the day, there should be some entirely *objective*
tests that determine conformance or non-conformance.  Citing
the technology problems of traditional Fax (analog lines)
and Internet mail (wide variation in quality of deployed
infrastructure) is a fruitless form of waffling.

My two cents,
- Ira McDonald (consulting architect at Sharp Labs America)
  High North Inc

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
Sent: Monday, January 24, 2000 5:52 PM
To: Keith Moore
Cc: Mark Fraser; IETF fax WG; IETF VPIM List
Subject: Re: [VPIM] Re: draft-ema-vpim-pndn-00.txt

> and I don't believe for a millisecond that email-to-foo gateway
> vendors/operators are going to be willing to return "failure"
> DSNs every time they can't translate every single portion of the
> message content.

Yup. And this isn't going to change no matter what the standards say.

				Ned

---

From: Keith Moore <[email-masked]>
Date: Tue, 25 Jan 2000 00:56:27 -0500

> interoperability testing is a waste of time for Internet

well, I don't believe that.  so there must be a gap somewhere.

first of all, interop testing potetntially has more means at 
its disposal to verify correct operation than an MTA or
gateway has.  at an interop test you can send a fax end-to-end
and compare the results with the original.  An MTA or gateway
that is trying to send back a non-delivery report cannot, in 
general, determine how much signal degradation has occurred.

Also, for the specific case of email-to-fax gateways I think you 
could (with some work) probably define reasonably good criteria for 
an overeall 'delivered with some degradation' vs.  'not delivered'
decision, where the criteria for 'delivered' is substantially better 
than 'anything goes' and not quite as stringent as 'every pixel on 
every page transmitted without error'.  And you could probably define 
similar criteria for other specific cases.  

What I don't think you can do  - or at least, I don't see how to do -
is define reasonable 'delivered' vs. 'not delivered' criteria for 
arbitrary multipart MIME messages.

Keith

---

From: [email-masked]
Date: Mon, 24 Jan 2000 22:06:12 -0800 (PST)

> interoperability testing is a waste of time for Internet

I'm sorry, but I reject this conclusion absolutely. Nothing either Keith or I
have said has anything to do with making quality of service a subjective
measure. You are confusing the things we've both said about the
delivered/not delivered indication we must provide with quality of service.
The two have little if anything to do with each other.

> tests that determine conformance or non-conformance.

I fail to see how any of this has anything to with conformance or
non-conformance. If you're referring to specifying a minimum set of
types that have to be supported, that's all well and good, but again it
has little if anything to do with the problem at hand.

> Citing

On the contrary, if we fail to examine the past and learn from it we
will simply make them all over again. This is about as far from waffling
as it gets.

				Ned

---

From: Graham Klyne <[email-masked]>
Date: Tue, 25 Jan 2000 10:37:35 +0000

I believe this debate has wandered somewhat from the original proposal that 
sparked it, and I'll try to use Keith's comment to bring it back...

>arbitrary multipart MIME messages.

This is exactly the point I was trying to address...

We have argued (I think we agree) that a partial NDN mechanism should be a 
natural extension of DSN that can reasonably be interpreted by existing 
DSN-aware senders.  This requires that the receiving MTA must make a 
judgement about overall success/failure for the purposes of DSN generation, 
even if it will supplement that information with partial delivery 
information (which, to partially address Ned's point, may help an NDN-aware 
sender to make an appropriate report to the user).

I was (implicitly) agreeing with Eric that if the original message is 
accompanied by critical part information (whatever that may be), then it is 
reasonable to declare success if all the critical parts are delivered.

But in the absence of such information, and given choice between declaring 
success or failure, then I was suggesting that failure to deliver _any_ 
part should result in a report of failure to deliver the message as a 
whole.  The alternative of declaring success seems unreasonable (but I am 
open to hear other proposals).

#g

------------
Graham Klyne
([email-masked])

---

From: Mark Fraser <[email-masked]>
Date: Tue, 25 Jan 2000 05:56:22 -0800

Thank you for expressing it so much better than I.
I agree completely / mark

---

From: Keith Moore <[email-masked]>
Date: Tue, 25 Jan 2000 11:23:46 -0500

> open to hear other proposals).

and - just to complete the summary - I have argued that this criteria
is not reasonable for a significant number of cases, and that (in the
absence of a per-part criticality flag) you cannot come up with good
criteria that should be applied in every case.

though, as I said earlier, you probably can come with reasonable
criteria for specific cases such as email-to-fax gateways

so I suggest that folks

a) define a per-part criticality flag
   (perhaps a content-disposition keyword?) , and 

b) define success/failure criteria for the specific cases that they're
   interested in.

Keith