Subject: RE: [Sip] INFO considered harmful

From: Adam Roach <[email-masked]>
Date: Thu, 2 Jan 2003 19:10:44 -0600

> From: Neil Deason [mailto:[email-masked]]
> 
> Actually if we want to police protocol usage closely we had 
> better look at deprecating MESSAGE too.

Come back when SIMPLE has finished defining the message sessions,
and I'll throw my voice behind yours in advocating this.

/a
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From: Henning Schulzrinne <[email-masked]>
Date: Thu, 02 Jan 2003 20:24:37 -0500

Actually, there's an important difference: MESSAGE can use the SIP 
features outside an established session, while INFO is within a session 
(and thus there are other SDP-negotiated, options available). Within a 
session, the only real reason for a follow-the-INVITE SIP message is 
that a direct IP-level connection can't be made to work.

 From an efficiency standpoint, if you only have very occasional 
messages, you gain by a "connectionless" approach. After all, an INVITE 
transaction for a single MESSAGE doesn't buy you much and doesn't 
conserve the oh-so-precious proxy cycles. While such short sessions are 
probably not common for human-to-human communication (except spam...), 
they may well be common for the type of things that SMS and pagers are 
popular for: machine-to-human or machine-to-machine communications 
announcing infrequent and unpredictable events ("your flight is now 
leaving on gate 37", "your FedEx just arrived", "Server 42 is on fire").

---

From: "Neil Deason" <[email-masked]>
Date: Thu, 2 Jan 2003 18:56:23 -0800

> -----Original Message-----
> From: Adam Roach [mailto:[email-masked]]
>

What I was actually advocating here was ppl wanting to keep INFO around
write up something to illuminate INFO packages and provide example
usage.

The MESSAGE cf INFO was just an attempt to highlight an apparent
limitation with the ban INFO approach. Every MIME type in an INFO can be
moved into MESSAGE rather than go away. Maybe through exploring INFO
packages we evolve the collective understanding that this is/isn't a
necessary thing.

Cheers,
Neil.

---

From: Jonathan Rosenberg <[email-masked]>
Date: Fri, 03 Jan 2003 01:17:41 -0500

inline.

> write up something to illuminate INFO packages and provide example

Well, let me suggest an amendment to that.

It seems that people have a bunch of problems they want to solve, for 
which they are finding INFO a good solution. They have some requirements 
like, "support application to application messaging", and other folks, 
like myself, have requirements for things like congestion control and 
the ability to indicate what kind of usages are supported. It seems like 
RFC 3427 is screaming at us here. Someone needs to write down what 
problems they are trying to solve, and then sipping can debate them. If 
we choose to address them, the sip working group might conclude that it 
should revise INFO to meet those requirements, or it might decide to 
obsolete it in favor of a totally separate solution (like my proposed 
SDP-based approach).

Given the volume on this thread during the holiday season even, there 
should be no shortage of volunteers to write such a requirements doc. 
For once though, I am NOT volunteering ;)

-Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.                72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
[email-masked]                     FAX:   (973) 952-5050
http://www.jdrosen.net                      PHONE: (973) 952-5000
http://www.dynamicsoft.com

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From: Jonathan Rosenberg <[email-masked]>
Date: Fri, 03 Jan 2003 01:19:19 -0500

Henning is dead on.

I think we will always need MESSAGE for this reason exactly. It may be, 
that as messaging sessions are completed, and we understand the problem 
space better, we would revise MESSAGE to impose further restrictions on 
it. For now, I think its pretty good as written.

-Jonathan R.

Henning Schulzrinne wrote:
>>> Actually if we want to police protocol usage closely we had better 
>>> look at deprecating MESSAGE too.
>>
>>
>>

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From: "Dean Willis" <[email-masked]>
Date: Fri, 3 Jan 2003 17:13:20 -0600

> What I was actually advocating here was ppl wanting to keep 
> INFO around write up something to illuminate INFO packages 
> and provide example usage.
> 
> The MESSAGE cf INFO was just an attempt to highlight an 
> apparent limitation with the ban INFO approach. Every MIME 
> type in an INFO can be moved into MESSAGE rather than go 
> away. Maybe through exploring INFO packages we evolve the 
> collective understanding that this is/isn't a necessary thing.
> 
> Cheers,
> Neil.

This is an excellent suggestion, and very similar to the one Jonathan made
to me on the phone yesterday (actually, I think he more tersely worded it as
"Send Text!")

--
Dean

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From: "Frank W. Miller" <[email-masked]>
Date: Fri, 3 Jan 2003 19:02:24 -0500

Well, any illusion of reasonableness I may have garnered in the past is
about to be shattered.  I would refer folks to:

http://www.ietf.org/internet-drafts/draft-miller-sip-isup-annex-00.txt

This draft is about to receive a major -01 update that recodes the entire
syntax in XML.  In addition, we (I) have another draft that does something
very similar for ANSI TCAP that I'll be submitting in short order.  I guess
its only appropriate that I bring peoples attention to these drafts under
the current subject heading...

FM

Frank W. Miller, Ph.D.
Chief Technical Officer
sentitO Networks, Inc.
[email-masked]

----- Original Message -----
From: "Dean Willis" <[email-masked]>
To: "'Neil Deason'" <[email-masked]>; "'Adam Roach'"
<[email-masked]>
Cc: <[email-masked]>
Sent: Friday, January 03, 2003 6:13 PM
Subject: RE: [Sip] INFO considered harmful

---

From: Christer Holmberg <[email-masked]>
Date: Thu, 09 Jan 2003 10:48:47 +0200

Hi,

> that a direct IP-level connection can't be made to work.

[CHH]  Please remember that in SIP-T there are needs to send INFO BEFORE the
200 OK has been sent for INVITE, which means the SDP negoatiation MAY not be
finished yet. I don't know about any other mechanisms using INFO which
require to be able to do the same, but just to keep in mind...

Regards,

Christer Holmberg
Ericsson Finland