[itu-sg16] Instant Messaging in H.323 & Common Alerting Protocol (CAP)

Simon Horne s.horne at packetizer.com
Wed May 23 21:55:29 EDT 2007


Hi

Just like to chime in, as the author of the Text Messaging proposal for H.323.

How would we do CAP in the real world (outside VoIP or the internet) ?  The 
easiest and most efficient method is to broadcast an SMS on the mobile 
phone to everyone. That is exactly what is being used in Indonesia today to 
advise the citizens of impending trouble. They have used it several times 
over the last couple of years with some success (luckily with little 
fatalities). SMS really works for this type of thing.

The short messaging outside the context of a call (can also be done in a 
call) in the IM proposal for H.323 has exactly the same function as SMS. A 
message is sent (using a lightweight call setup) and appears on the users 
computer or hardware device. It is very simple and efficient as it doesn't 
need to establish any media streams. We can assign CAP messages a priority 
field so the user's device will react in a different way to alert the user 
this is an important message.

Simon

At 08:50 AM 24/05/2007, Christian Groves wrote:
>G'Day Paul,
>
>Please my comments below CNG.
>
>As an aside, do you know if there's any work in the IETF around CAP?
>
>Regards, Christian
>
>Paul E. Jones wrote:
>>Christian,
>>
>>We already do have a means in H.323 doing a wide-spread "message broadcast"
>>in H.323 (H.460.21), which would accommodate recorded messages (audio,
>>video, or real-time text).  My initial thinking for CAP was that the
>>emergency message would be delivered to the broadcast center, translated
>>from CAP into one of the above mentioned forms, and then broadcast via
>>H.460.21 to the H.323 terminals within range.
>>
>[CNG] I know we have this capacity that's why I think it would be 
>worthwhile to describe in a Annex/Appendix titled something like "CAP 
>usage in H.323 systems".
>>However, it seems that another request is to use H.323 in order to actually
>>transmit the CAP message as-is between communicating H.323 devices.  Perhaps
>>this might only be used between broadcast centers, or perhaps it might be
>>the form of communication sent to all terminals (as opposed to sending the
>>audio/video/text stream).  In any case, the request before us is to define a
>>means of conveying CAP messages between H.323 terminals.
>>
>[CNG] With regards to the request, are you referring to a liaison or a 
>request by some end user? At least for me it would be good to have a 
>submission by an end user into this discussion. Do you know anybody (or 
>anybody on the list) who would be using or implementing this service? 
>Having their input would help the discussion in SG16.
>
>>So, the question then is "how"?  Do we use an IM mechanism that is capable
>>of delivering any kind of "text" (including human-entered, CAP message, a
>>emoticon, a sound bit, or other), or do we create something special just for
>>CAP?  I would prefer to avoid the latter, personally.
>>
>[CNG] I'm usually for "generic" type mechanisms that can be re-used. From 
>the other emails from what I'm reading is that why re-invent/implement 
>something where there's an existing solution.
>>So, does that help your thinking?  Or, did I muddy the water?
>>
>[CNG] I agree with you on the 2 usages of the CAP as you described above. 
>Given that CAP could be a rather important tool in the future I'd like to 
>see that whatever solution we chose meets the requirements of those using 
>it. That's why I think it would be good to have an end user perspective of it.
>>Paul
>>
>>
>>>-----Original Message-----
>>>From: Christian Groves [mailto:Christian.Groves at nteczone.com]
>>>Sent: Tuesday, May 22, 2007 8:05 PM
>>>To: Paul E. Jones
>>>Cc: itu-sg16 at lists.packetizer.com
>>>Subject: Re: [itu-sg16] Instant Messaging in H.323 & Common Alerting
>>>Protocol (CAP)
>>>
>>>G'Day Paul,
>>>
>>>Before drawing a conclusion that sending IMs within a the context of a
>>>call is the answer for CAP should we perhaps look at the requirements
>>>that are implied by CAP? From my reading of CAP the ASN.1 is a
>>>description of the information that is associated with the emergency.
>>>This information is used by emergency agencies to take action. As a
>>>result of this information various actions can be triggered across
>>>communications networks. E.g. phones rung and an announcement played, a
>>>guy on a motorbike sent out to scream "run for your lives". If we look
>>>at the information in the CAP perhaps the ASN.1 description of CAP
>>>maybe
>>>more effectively rendered for use by emergency by a web type interface
>>>that shows the co-ordinates from the ASN.1 in a graphical format. So
>>>perhaps there is a need for an IM to say "Emergency look at URL xxx for
>>>CAP" but does this necessarily have to be H.323 based?
>>>
>>>In terms of H.323 I see some sort of multi-cast announcement service
>>>where elements of the CAP information are sent to H.323 end points via
>>>audio, video, stills, text and how this relates to priority handling is
>>>something that would be more appropriate to describe.
>>>
>>>I don't have any particular objection if someone wants to start work on
>>>IM in H.323 but I'm not sure that CAP alone justifies it.
>>>
>>>Regards, Christian
>>>
>>>Paul E. Jones wrote:
>>>
>>>>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
>>>>
>>>>
>>
>>
>>
>>
>>
>>






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