From:
itu-sg16-bounces@lists.packetizer.com
[mailto:itu-sg16-bounces@lists.packetizer.com] On Behalf Of Paul E.
Jones
Sent: Tuesday, May 22, 2007 11:36 PM
To: 'Gary Sullivan'; itu-sg16@lists.packetizer.com
Subject: Re: [itu-sg16] Instant Messaging in H.323 & Common
AlertingProtocol(CAP)
Gary,
T.134 is an application protocol
entity for sending text messages within the context of a T.120
conference. So, it’s not usable within H.323.
T.140 is a character
presentation format and is used by H.323 Annex G for delivering real-time
text. However, real-time text and Instant Message are not the same (so
I’m getting closer to answering your question).
V.18 is a protocol for sending
text over a PSTN circuit using modulated signals (modem), so that’s far
away from what we’re doing in H.323 (or IP networks in general).
So what is the difference
between H.323 Annex G (real-time text) and Instant Messaging? The
difference is how messages are composed, transmitted, and delivered. With
H.323 Annex G, characters are collected and transmitted as they are entered by
the user and then displayed on the remote device “character at a
time” (or as close to that as possible). With Instant Messaging
(IM), entire sentences or paragraphs are entered and then transmitted as a
single message block. The latter is what we see with MSN Messenger, Yahoo
Messenger, Sametime, Jabber / XMPP / Google Talk, AIM, and other similar
clients.
The desire that has been
expressed since at least 2000 is to support some form of IM in H.323.
We’ve had several proposals and nothing has moved forward beyond the
initial presentation (or at most the second meeting). I never understood
why, but now we have a situation where we’re being asked to deliver what
is essentially a “text message”. If we have an IM protocol in
place, it would become trivial to deliver that capability. Thus,
I’d like to see hastened forward progress on the IM work we’ve been
debating for so many years.
I hope that helps.
Paul
From: Gary Sullivan
[mailto:garysull@windows.microsoft.com]
Sent: Tuesday, May 22, 2007 4:14 PM
To: Paul E. Jones; itu-sg16@lists.packetizer.com
Subject: RE: [itu-sg16] Instant Messaging in H.323 & Common Alerting
Protocol(CAP)
Paul et al,
What is the difference between "IM" and "text
chat"?
And how do these efforts relate to the following?:
T.134 – Text chat in data conferencing
T.140 – Protocol for multimedia application text conversation
V.18 – Text telephony
From: itu-sg16-bounces@lists.packetizer.com
[mailto:itu-sg16-bounces@lists.packetizer.com] On Behalf Of Paul E.
Jones
Sent: Monday, May 21, 2007 9:23 PM
To: itu-sg16@lists.packetizer.com
Subject: [itu-sg16] Instant Messaging in H.323 & Common Alerting
Protocol(CAP)
Folks,
We have debated the introduction of a method of sending IMs
within H.323 for years. It’s unfortunate, especially considering
how the H.323 infrastructure so easily lends itself to such
functionality. There was a renewed hope with some documents introduced
during the Shenzhen meeting that suggested a means of sending IM within the
context of a call, as well as outside the context of a call.
One of the other matters we were asked to consider within
the context of H.323 and H.248 is the transmission of emergency messages using
a format called the “Common Alerting Protocol”. During the
Shenzhen meeting, we sent a liaison to SG17 urging them to consider the
creation of an ASN.1 specification that would more readily transport within
H.323 networks. I can report that, not only did they do that, it has been
put forward for consent already. The standard will be X.1303.
So, the next step is to define procedures for transporting
X.1303 (CAP) messages within H.323. Initially, I considered creating an
H.460.x extension, but then I thought that a better solution might be to use
something like H.450.7 (Message Waiting Indicator). But, as I thought
about this, perhaps the best way is to marry this with the Instant Messaging
proposals we’ve seen before.
If we were to standardize the ability to send instant
messages within H.323, both within and outside the context of a call, then it
would be possible to send X.1303 messages as an “instant
message”. This does introduce a new requirement, though, in that we
ought to “tag” the type of message so that it is properly
treated. Instant Messages might appear unprocessed on the user’s
screen, whereas X.1303 messages must be decoded and formatted for human readability.
So, I would like to draft a proposal for this upcoming SG16
meeting to do precisely what I said: let’s move forward on the work of
sending IM messages within H.323, adding a tag that indicates the type of
message. We can also utilize the call priority procedures in H.460.4 in
order to ensure that an emergency CAP message gets higher priority through the
network.
Does this sound reasonable and acceptable? Do others
have other proposals?
If it is acceptable, then I have a question of procedure.
The proposals for instant messaging were not accepted as new work items
for Q2, though they were not rejected: the request was for further
progress. Unfortunately, the contributor is not a member of the ITU,
which leaves us in a difficult situation. As a possible means forward
somebody might volunteer to submit these documents as formal contributions to
this SG16 meeting under their company’s name. Is that agreeable and
are there any volunteers?
Do you have another idea for how we can support X.1303 (CAP)?
Thanks,
Paul