Subject: RE: WG Review: Centralized Conferencing (xcon)

From: "Peterson, Jon" <[email-masked]>
Date: Tue, 19 Aug 2003 18:03:45 -0500

[from the charter text]
> Initially this combination of protocols will be specified with respect
> to session setup with SIP. The solutions developed in XCON will not
> preclude operation with other signaling protocols; however it is
> anticipated that the use of other protocols would require modifications
> which are out of scope for this working group.

Regarding the name 'xcon' versus something like 'sipxcon', as the paragraph
above states, XCON does not want to preclude the possibility that its
mechanisms will work with other signaling protocols. It's possible that a
mechanism for conference control designed with SIP in mind could have some
applicability to other protocols (MGCP and Megaco come to mind - more likely
than not, anything SDP-based - but perhaps even non-IETF protocols like
H.323, and so on). In that sense I think the work really is somewhat more
generic than SIP - the group will not go out of its way to ensure its
applicability elsewhere, but the work isn't so tightly-coupled to SIP that
applicability in the rough neighborhood is impossible or even vastly
unlikely. 

As far as I can tell, the paragraph above strikes the right balance, and
doesn't make unreasonable or ambitious claims about applicability. Perhaps
that paragraph's wording could be improved, or it could be placed more
prominently in the charter, or something (suggestions welcome). But I can't
imagine the charter text could be construed to imply that protocols like,
for example, XMPP would be bound or even encouraged to support the results
of XCON.

Jon Peterson
NeuStar, Inc.

> -----Original Message-----
> From: Marshall Rose [mailto:[email-masked]]
> Sent: Tuesday, August 19, 2003 3:29 PM
> To: Peterson, Jon
> Cc: [email-masked]
> Subject: Re: WG Review: Centralized Conferencing (xcon)
> 
> 
> jon - sorry for the delay in replying.
> 
> fundamentally, i think it comes down to accuracy in 
> labelling. if the sip
> folks want to do conferencing, then they should have a 
> working group to do
> that. however, the charter for that working group should not 
> imply that the
> scope of the working group is anything beyond sip.
> 
> a reasonable person reading the charter would conclude that 
> the scope of the
> working group is somewhat more generic than sip.
> 
> if the goal for this working group is to be generic, then the 
> charter is
> likely unacceptable since it assumes "facts not entered into 
> evidence",
> i.e., it is sip-centric, and there is a fair body of deployed 
> work that
> manages to do conferencing very well without using that 
> acronym. if that is
> not the intention, then  i suggest that the working group be called
> something like sipxcon to avoid any confusion.
> 
> as to whether the working group belongs in apps or tsv, a generic
> conferencing working group clearly belongs in apps. however, 
> a sip-specific
> working group can probably comfortably reside in either.
> 
> /mtr
>

---

From: Harald Tveit Alvestrand <[email-masked]>
Date: Tue, 19 Aug 2003 19:54:50 -0700

listening in on this conversation, it seems to me that Marshall is talking 
about "conferencing" in a sense which includes a lot of different 
mechanisms, the premier one being instant messaging, while Jon (and the 
XCON charter) speaks about "conferencing" in a sense that starts out 
assuming that voice is included, and that video is the logical next step, 
while conferencing based on IM, if thought of at all, is regarded as a 
small side issue.

I don't know how to add markers to the charter to make it obvious how the 
word "conferencing" is intended here, however. And it may not even make the 
issue go away.

And, of course, I may have misunderstood the charter (or Marshall).

                      Harald

---

From: Ari Ollikainen <[email-masked]>
Date: Tue, 19 Aug 2003 23:25:38 -0700

At 7:54 PM -0700 8/19/03, Harald Tveit Alvestrand wrote:
>listening in on this conversation, it seems to me that Marshall is talking about "conferencing" in a sense which includes a lot of different mechanisms, the premier one being instant messaging, while Jon (and the XCON charter) speaks about "conferencing" in a sense that starts out assuming that voice is included, and that video is the logical next step, while conferencing based on IM, if thought of at all, is regarded as a small side issue.
>
>I don't know how to add markers to the charter to make it obvious how the word "conferencing" is intended here, however. And it may not even make the issue go away.

	In the context of audio and video conferencing why not add those
	words to the description...we've been here before (~10 years ago
	with the remconf BOF and its spinoffs).

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       OLTECO                    Ari Ollikainen
       P.O. BOX 20088            Networking Architecture & Technology
       Stanford, CA              [email-masked]
       94309-0088                415.517.3519

---

From: Dave Crocker <[email-masked]>
Date: Wed, 20 Aug 2003 10:40:36 -0700

Jon,

Perhaps it will help to consider the proposed text from the vantage
point of someone who is not already familiar with SIP and SIP history.

It might also help to consider how concrete (or not) the proposed
language is:

PJ> [from the charter text]
>> to session setup with SIP.

This says that SIP provides a basis, but there is no indication of what
this means. There is no operationally or technically objective meaning to
"specified with respect to". It could mean absolutely anything. So the
text is conceptual, rather than concrete.

That is, it states a philosophical focus on SIP, but nothing more.  In
terms of "contract" language, it has no content that can be enforced.
The one possible use of this sentence is to provide a basis for
excluding non-SIP work.

>> The solutions developed in XCON will not
>> preclude operation with other signaling protocols;

Again, this is a statement of philosophy that has no operational or
technical meat to it.  In the abstract, yes, one can do things to
preclude operation with other signalling protocols, but there is no
well-established set of design actions that folks will know about, for
creating such "preclusion".

Further, it is pretty darn rare to have a working group do anything to
"preclude" actions outside of the working group scope.

In fact there is a track record of design work that says the actual
outcome of the working group will be the opposite of what the charter
text declares: Absent careful attention to other uses, a design tends to
be workable only for the envisioned scenario.

>> however it is

In other words, this is work that is only for SIP.

PJ> Regarding the name 'xcon' versus something like 'sipxcon', as the paragraph
PJ> above states, XCON does not want to preclude the possibility that its
PJ> mechanisms will work with other signaling protocols.

Actually, yes it does. The SIP environment is the only scope of this work.

Unless the charter states what will be done to *ensure* that other
signalling environments can be supported, the odds are quite high that
none will be possible.

PJ> It's possible that a mechanism for conference control designed with
PJ> SIP in mind could have some applicability to other protocols

Unfortunately, this sort of statement has no effect. Anything is
"possible". So the text is just commentary about the unknown future.

On the average, it has no place in a charter, because it says nothing
about what what the working group will or will not do. Yet that is the
purpose of a charter.

d/
--
 Dave Crocker <mailto:[email-masked]>
 Brandenburg InternetWorking <http://www.brandenburg.com>
 Sunnyvale, CA  USA <tel:+1.408.246.8253>, <fax:+1.866.358.5301>

---

From: Dave Crocker <[email-masked]>
Date: Wed, 20 Aug 2003 10:40:36 -0700

Jon,

d/