Subject: [Sipping] DialogUsage: How strong should the admonition against multiple usages be

From: Robert Sparks <[email-masked]>
Date: Tue, 22 Nov 2005 16:31:27 -0600

Some recent list traffic (Paul and Dale) pushes back against the current
position in the draft that multiple usages are "bad".

I believe this is the consensus of the group, but since I feel  
strongly this way myself,
I may be inappropriately biased. Please weigh in so I (and the  
chairs) can take
another reading.

Specifically, should the draft say "Multiple usages are bad, don't do  
things to make
more of them going forward", or should it be toned back to "Multiple  
usages have
the following ambiguities - here's the recommended resolution of  
them" and make
no statement around whether applications should consider entering  
into them.

Thanks,

RjS

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---

From: Paul Kyzivat <[email-masked]>
Date: Tue, 22 Nov 2005 18:08:54 -0500

Robert Sparks wrote:
> I believe this is the consensus of the group, but since I feel  strongly 
> this way myself,
> I may be inappropriately biased. Please weigh in so I (and the  chairs) 
> can take
> another reading.
> 
> the following ambiguities - here's the recommended resolution of  them" 
> and make
> no statement around whether applications should consider entering  into 
> them.

I would be satisfied with something in between:

"Multiple usages have the following ambiguities - here is the 
recommended resolution for them. Yadda yadda. Multiple usages also have 
some consequences that make them difficult to use in some cases. Yadda 
yadda. Be sure to take these consequences into account when deciding 
whether to employ multiple usages."

(In other words: this is playing with fire. While fire is sometimes 
useful, little kids shouldn't do it.)

	Paul

---

From: Jonathan Rosenberg <[email-masked]>
Date: Wed, 23 Nov 2005 09:54:00 -0500

I thought we had concluded they were bad, and this was one of the 
motivating factors for specs like gruu and target-dialog.

-Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.                   600 Lanidex Plaza
Director, Service Provider VoIP Architecture   Parsippany, NJ 07054-2711
Cisco Systems
[email-masked]                              FAX:   (973) 952-5050
http://www.jdrosen.net                         PHONE: (973) 952-5000
http://www.cisco.com

---

From: Paul Kyzivat <[email-masked]>
Date: Wed, 23 Nov 2005 11:53:41 -0500

Its a matter of degree. Having the alternative mechanisms is good. But I 
don't think it is inconsistent to acknowledge the other mechanism is 
still useful in certain cases.

	Paul

Jonathan Rosenberg wrote:
>>> Specifically, should the draft say "Multiple usages are bad, don't 
>>> do  things to make
>> recommended resolution for them. Yadda yadda. Multiple usages also 
>> have some consequences that make them difficult to use in some cases. 
>> Yadda yadda. Be sure to take these consequences into account when 
>> deciding whether to employ multiple usages."
>>

---

From: Jonathan Rosenberg <[email-masked]>
Date: Wed, 23 Nov 2005 12:07:33 -0500

In which cases? I thought we were documenting it to clarify it, since 
its (under) specified in rfc3261, but recongizing the limitations we've 
produced gruu and target dialog so we could go away from multiple usages.

-Jonathan R.

Paul Kyzivat wrote:

>>>> more of them going forward", or should it be toned back to 
>>>> "Multiple  usages have

---

From: "Vijay K. Gurbani" <[email-masked]>
Date: Wed, 23 Nov 2005 11:22:33 -0600

> still useful in certain cases.

I am looking at this from an implementation point of view: having
alternative mechanisms for doing the same thing lead to all
sorts of interoperability problems.

We are dealing with one right now in the double R-R vs. response
re-writing.  Admittedly, that one is not as severe as multiple
dialog usage one, but it is ambiguity all the same.

It'll be good if we pick *one way* and stick with it.  For the record,
I thought that we had agreed that dialog sharing was bad and
we were going to deprecate it.

Thanks,

- vijay
-- 
Vijay K. Gurbani, Ph.D.  vkg@{lucent.com,research.bell-labs.com,acm.org}
Lucent Technologies/Bell Labs Innovations, 2000 Lucent Lane, Rm 6G-440
Naperville, Illinois 60566     Voice: +1 630 224 0216
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