Subject: RE: [Simple] IM over the signaling connection

From: "Robert Brown" <[email-masked]>
Date: Thu, 4 Oct 2001 14:04:41 -0700

In my opinion, while this topic has generated many creative alternative
proposals, *none* of them come close to the simplicity and effectiveness
of using MESSAGE (with/without INVITE) in the signaling band.

I agree with Ashvalom.  I'm completely perplexed by this IESG mandate.
It is totally unclear to me (and it sounds like I'm not alone) what the
actual disadvantage with in-band IM is.  
 
The signaling layer is already polluted with copious presence sessions
and messages.  Actual IM traffic is trivial compared to this.  I've
already posted an example that walks through the reasons for this.

I have seen it mentioned in a few threads that IM could be used to
transfer files or long monologues, hence could be a burden on SIP
proxies.  This is an abuse of the session.  If you want to transfer
files, negotiate a file transfer session.  IM should be text messaging
and the typical bit-rate is the speed of typing.  I could abuse NOTIFY
just as effectively since the presence document is extensible and
there's nothing to stop me including my autobiography, holiday snaps,
listings of all the MP3s on my hard disks, or whatever.

- Rob

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] 
Sent: Thursday, October 04, 2001 1:19 PM
To: Ben Campbell
Cc: [email-masked]
Subject: Re: [Simple] IM over the signaling connection

We have got the following wording:

<<<
The IESG has some concerns that this mechanism constitutes the use of
SIP
as a transport protocol. In other words, once the session has been
established
between the two endpoints by the INVITE, if the MESSAGEs can only go
directly end-to-end, then their headers and related protocol apparatus
are
entirely superfluous and may do more harm than good. We saw during the
meeting last week that there were definitely some pitfalls to allowing
methods other than MESSAGE across the IM stream (as well as questions
about
overlapping transactions, redirection, forking, and so forth), and it
isn't
clear that the overhead is justified if MESSAGE is just an envelope for
its
encapsulated MIME payload. The IESG was particularly concerned, in
addition
to the protocol overhead, with congestion characteristics of the
messaging
session and with the precedent that could be set by using SIP in this
fashion.

I am not sure if the IESG objects to the use of SIP as transport due to:
1. The signalling connection is for signalling only and not for any
media.
2. The overhead it will cause to the protocol.
3. The superfluos headers.

If it is 1, then why a single MESSAGE is allowed? if it 2 or 3, then we
can
limit the usage when the
session is held over the signaling connection.

avshalom
Sametime/Lotus/IBM

                    Ben Campbell

                    <bcampbell@dynami        To:     [email-masked]

                    csoft.com>               cc:
[email-masked]                                    
                                             Subject:     Re: [Simple]
IM over the signaling connection                
                    04/10/2001 17:28

It is not so much that it is being ignored as that the IESG has told us
they will not approve it.

[email-masked] wrote:

> It seems that the possibility of sending MESSAGEs of sessions over the
> signaling connection is being ignored.
> I am not sure that there is a consensus not to use it.
>
> It think that we can agree on sending MESSAGEs of sessions on the
control
> connection. We should keep the
> header of the MESSAGEs to a necessary minimum and agree on a maximum
length
> of MESSAGEs to be sent
> on the signaling connection. Given this, the impact on the control
> connection will not be different from a one time
> MESSAGE and NOTIFYs.
>
> avshalom
> Sametime/Lotus/IBM
>
>
> _______________________________________________
> simple mailing list
> [email-masked]
> http://mailman.dynamicsoft.com/mailman/listinfo/simple
>

_______________________________________________
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---

From: [email-masked]
Date: Fri, 5 Oct 2001 16:32:26 +0200

> The wording mentions 1 and 3 specifically. As far as why we allow
> page-model MESSAGE, there is some belief that chat sessions will
> typically involve more traffic (lots of short messages) than individual
> page-model messaging will.

What can happen if a session would not be allowed on the signaling
connection
is that people will send everything using page-model MESSAGE, even messages
that
would normally be part of a session. Using a session can save a lot of
headers
since a session id will replace some of the headers and maybe other methods
of
saving bandwidth can be deployed. Thus, permitting MESSAGEs of a session
over the
signaling connection can benefit the protocol rather then the opposite.
Limiting the size and rate of messages in the session negotiation will
help proxies and servers to know what bandwidth to expect and they can
prohibit
sessions that are too big. page-model MESSAGE will not give them these
capabilities.

> I do not understand what you mean by limiting the usage.

I meant limiting the size of the messages in the session negotiation.
Reading your
mail a rate limit seems also reasonable.

avshalom
Sametime/Lotus/IBM

                    Ben Campbell                                                                                       
                    <bcampbell@dynami        To:     [email-masked]                                               
                    csoft.com>               cc:     [email-masked]                                    
                                             Subject:     Re: [Simple] IM over the signaling connection                
                    05/10/2001 15:55                                                                                   

[email-masked] wrote:

> The IESG has some concerns that this mechanism constitutes the use of SIP
are
about
isn't
its
addition
messaging
media.
can
> session is held over the signaling connection.

The wording mentions 1 and 3 specifically. As far as why we allow
page-model MESSAGE, there is some belief that chat sessions will
typically involve more traffic (lots of short messages) than individual
page-model messaging will.

I do not understand what you mean by limiting the usage.