Subject: [Sip] INFO Issue: Multiple Bodies

From: Eric Burger <[email-masked]>
Date: Fri, 1 Aug 2008 16:07:37 -0400

The current text says we do not allow multiple Info-Packages per INFO  
message.  Although not stated (and I will state explicitly if we  
continue to go in this direction), this nominally makes parsers easier  
and makes failure handling straightforward.

I would offer the former issue is not real.  Namely the way of  
transporting multiple Info-Packages in an INFO message would be to  
encapsulate in a multipart MIME body.  However, all SIP endpoints must  
support multipart MIME, so this is a non-issue.

The latter issue is quite true in theory.  If I send two Info Package  
bodies, and for some reason the UAS barfs on one of those bodies, the  
UAS does not have a clean way of indicating which body barfed, and  
both effectively get treated at the UAC as failed.  The reason I  
caveated this issue "in theory" is I cannot think of a situation where  
this would matter.  Most of these usages are all-or-nothing, which  
means simply failing is OK.

Moreover, I would offer the first thing people will ask for is  
transporting multiple INFO messages in a single message....
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From: Paul Kyzivat <[email-masked]>
Date: Sat, 02 Aug 2008 10:33:37 -0400

I think banning multiple body parts is a bad precedent to set right when 
we are trying to foster widespread support of multipart.

	Paul

Eric Burger wrote:
> UAS does not have a clean way of indicating which body barfed, and both 
> effectively get treated at the UAC as failed.  The reason I caveated 
> this issue "in theory" is I cannot think of a situation where this would 
> matter.  Most of these usages are all-or-nothing, which means simply 
> failing is OK.
>

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From: "Christer Holmberg" <[email-masked]>
Date: Sat, 2 Aug 2008 23:11:33 +0200

Hi,
 
I don't think we should ban support of multipart at this point.
 
Regards,
 
Christer

________________________________

Lähettäjä: [email-masked] puolesta: Paul Kyzivat
Lähetetty: la 2.8.2008 16:33
Vastaanottaja: Eric Burger
Kopio: SIP IETF
Aihe: Re: [Sip] INFO Issue: Multiple Bodies

        Paul

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From: Dean Willis <[email-masked]>
Date: Tue, 05 Aug 2008 11:24:10 -0500

> and makes failure handling straightforward.

I support single packages per message; although it might be reasonable
that some package itself use a multipart content delivery.

For example, a "surf&turf" INFO package might contain a steak and a
lobster. This creates no consternation for the consumer, because that's
what he asked for, and if he can't handle a multipart, he should have
ordered something else.

--
Dean

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From: Eric Burger <[email-masked]>
Date: Mon, 11 Aug 2008 22:27:11 -0400

What is at Steak here [sic] is not whether an Info-Package can be a  
multipart MIME type.  That (almost, but clearly I guess I need to  
include such text) goes without saying (but will in the future).

The question is if I will eat Steak, and I will eat Lobster, is it OK  
for me to receive an INFO that has a multipart/mixed with one part  
being Steak and another (theoretically unrelated) part being Lobster?

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From: Dean Willis <[email-masked]>
Date: Mon, 11 Aug 2008 21:28:29 -0500

On Aug 11, 2008, at 9:27 PM, Eric Burger wrote:

> The question is if I will eat Steak, and I will eat Lobster, is it  
> OK for me to receive an INFO that has a multipart/mixed with one  
> part being Steak and another (theoretically unrelated) part being  
> Lobster?

Clearly, any client that doesn't understand multipart will be left  
asking "Where's the beef?"

--
Deab

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From: Eric Burger <[email-masked]>
Date: Mon, 11 Aug 2008 23:15:53 -0400

But on the serious side, my guess is the chance of a UA that  
understands "modern" Info-Packages but does not understand multipart/*  
will approach zero.  Especially if Info-Packages mandates support of  
multipart.

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From: "Francois Audet" <[email-masked]>
Date: Mon, 11 Aug 2008 20:41:47 -0700

Especially if we mandate support for multipart MIME in modern Info-package.

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From: Dean Willis <[email-masked]>
Date: Tue, 12 Aug 2008 10:47:33 -0500

On Aug 11, 2008, at 10:15 PM, Eric Burger wrote:

> understands "modern" Info-Packages but does not understand multipart/ 
> * will approach zero.  Especially if Info-Packages mandates support  
> of multipart.

I believe you are correct.

--
Dean

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From: "DRAGE, Keith \(Keith\)" <[email-masked]>
Date: Wed, 13 Aug 2008 23:27:53 +0200

There is a documentation rathole here that we will need to resolve
sometime.

My understanding is that draft-ietf-sip-body-handling updates RFC 3261
and this mandates the support of multipart.

Any referencing should therefore reference RFC 3261 as updated by
draft-ietf-sip-body-handling.

However we are still left with the problem that the INFO documentation
is in an RFC that still references RFC 2543, and therefore misses this
part of the documentation entirely.

Regards

Keith 

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On 
> Behalf Of Francois Audet
> Sent: Tuesday, August 12, 2008 4:42 AM
> To: Eric Burger; Dean Willis
> Cc: SIP IETF
> Subject: Re: [Sip] INFO Issue: Multiple Bodies
> 
> > This list is for NEW development of the core SIP Protocol Use 
> > [email-masked] for questions on current sip Use 
> > [email-masked] for new developments on the application of sip
> 
> This list is for NEW development of the core SIP Protocol Use 
> [email-masked] for questions on current sip

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From: Dean Willis <[email-masked]>
Date: Wed, 13 Aug 2008 18:15:55 -0500

> part of the documentation entirely.

Oh gee, maybe we ought to revise INFO?

--
Dean