Subject: RE: [Simple] SIP & Presence - Joined@Hip?

From: Jonathan Rosenberg <[email-masked]>
Date: Thu, 26 Jul 2001 15:18:06 -0400

Nothing in the archives? The entire history of the impp ->
{simple,prim,apex} split center around these issues exactly. There are
countless posts over years of impp discussions, not to mention talks and
presentations, on this topic. 

BRIEFLY, its because (1) sip networks already have presence as its needed
for session intitiaton, (2) delivery of presence and notificaiton messages
to people is supported on top of existing proxy networks, (3) presence and
IM are both parts of a broader communications service that also includes
voice, video, etc., and it would be nice to smoothly integtrate those
together, (4) when doing a requirements analysis on the protocols we found
that much of whats needed is already provided by SIP. 

-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
  
-----Original Message-----
From: Zane Thomas [mailto:[email-masked]]
Sent: Thursday, July 26, 2001 2:30 PM
To: [email-masked]
Subject: [Simple] SIP & Presence - Joined@Hip?

Hmm, I'm reticent to raise this issue since I'm sure that it has been beaten
to death in the past - I must have missed something in the archives.
However ...
 
Could someone explain to me why modifying SIP to support Presence etc is
being considered?  There have been some instances in the archived
discussions where proposed solutions for handling authorization lists, for
instance, have become discussions about what's the best SIP-way to handle
the problems being discussed.  The net result, for me, has been the
impression that SIP has its own simple and reasonably well-defined goals
which are distinct *for the most part* from those of Presence, and that
trying to merge the two sets of goals will limit and complicate both.
 
I wonder, for instance, why it's not simply good enough to add something
like:
 
    <pres:[email-masked]>
 
to the Contact header and then have a seperate and unconstrained discussion
of presence subscriptions and related issues.
 
Zane

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From: "Zane Thomas" <[email-masked]>
Date: Thu, 26 Jul 2001 14:11:27 -0700

Jonathan,

Thanks for the reply.

> Nothing in the archives?

I certainly didn't mean to imply that there *was* nothing in the archives.
What I meant to say was that I spent many hours yesterday reading the SIMPLE
archives and *I* didn't see the background material - I went back and looked
some more this morning before posting.  I realize it can be annoying when
newbies come along so late in the discussion and ask what can be rather
fundamental questions, so I made an effort.

If you would like to direct my attention to other relevant archives and etc
I will be *more than happy* to take a look - feel free to make any such
suggestions as preliminary (or conclusive) replies to my further
questions/comments.

> (1) sip networks already have presence as its needed
> for session intitiaton

Yes, as it's needed for Initiation.  But apparently not as needed in the
more general sense - otherwise there wouldn't be any discussion about
extending it.

> (2) delivery of presence and notificaiton messages
> to people is supported on top of existing proxy networks

Yes, I understand that.

> (3) presence and
> together

You're losing me there.  I see that there are things like RTP for carrying
"real time" data.  That makes sense to me, you use SIP to initiate a session
and SDP to specify RTP, for instance.  What I don't understand is why IM is
being handled differently.  Also from draft-rosenberg-impp-im-01.htm I see
the following:

"Instant messaging is defined as the exchange of content between a set of
participants in real time. Generally, the content is short textual messages,
although that need not be the case."

Aside from the admittedly not insignificant differences between the
different types of "real time" data represented by IMs and audio, for
instance, it's not clear to me what is so *fundamentally* different that IM
should have special status in SIP.

I realize there is some difficulty in defining exactly what a Session is
with IM but it seems to me that any particular IM application might choose
to define one in a number of different ways.  For instance, I might define a
Session (from the SIP perspective) as two peers knowing each other are
online and establishing UDP ports to use for exchanging messages.  Above
that - in my application - I might further define another type of Session
which consisted some sequences of message-reply pairs, for the purpose of
providing convenient views of message history.

Another thing that occured to me is that if you provide an arbitrarily large
MESSAGE which can be sent over SIP proxys then it won't be long before the
SIP servers are carrying a lot of traffic containing MP3 files.

 >(4) when doing a requirements analysis on the protocols we found

Is that information available on the web somewhere?

Tia,

Zane

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From: Ben Campbell <[email-masked]>
Date: Thu, 26 Jul 2001 16:40:15 -0500

> suggestions as preliminary (or conclusive) replies to my further

The discussions Jonathan refers to would be in the IMPP archives, not 
the SIMPLE archives. These discussions predated the formation of the 
SIMPLE group (and in fact led directly to its formation.) You will 
probably need to go back about a year to find them.

---

From: "Zane Thomas" <[email-masked]>
Date: Thu, 26 Jul 2001 15:12:47 -0700

Ben,

> The discussions Jonathan refers to would be in the IMPP archives ...

Thanks for the tip, I'll go look for the archive.

Zane