Subject: Re: [SIP] Instant Messaging....

From: [email-masked]
Date: Thu, 17 Aug 2000 17:44:19 +0530

How does it solve instant messaging, by simply registering an IANA port and
specifying m= line as you say ?

Which method do you send it in ? Where do you encapsulate the actual text ?
Would you want to overload INVITE yet again ? (also invite requires the
INV-OK-ACK negotiation cycle - doesnt make
sense for an IM message going forward)
Other methods like INFO , BYE etc already have a specific application .
(Actually the way it seems to be going now is that INFO is so generic that
it doesnt seem to be used much at all !:-p !)

I would say MESSAGE (Its a method, not a header) is still very much
required.
There are other advantages of using a different method (one is proxies who
do not support IM can simply
return "Method not supproted" whenever a MESSAGE comes across, instead of
trying to decipher if it was a method
it allowed, which is encapsulating an IM behaviour - etc. ) See the impp
drafts for more details.

Regds
Arjun

--
Arjun Roychowdhury @ Hughes Software Systems

"rahul pande" <[email-masked]> on 08/17/2000 04:11:34 PM

To:   [email-masked]
cc:

Subject:  [SIP] Instant Messaging....

hello,
     I was wondering that once the TCP transport port is registered under
IANA will we still require the MESSAGE header(presently in the drafts
stage)
since a line such as :
         m=text <port> tcp plain
     with other a= attributes proposed for tcp will solve the problem for
instant messaging.
     Thanking you all,
        rahul
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From: "rahul pande" <[email-masked]>
Date: Fri, 18 Aug 2000 10:13:26 GMT

Message received :

>How does it solve instant messaging, by simply registering an IANA >port 
>and specifying m= line as you say ?
>Which method do you send it in ? Where do you encapsulate the actual >text 
>?

Sir,I was refering to the INVITE method only.

>sense for an IM message going forward)

Sir,Its only the initial call setup overhead just like for any other media 
communication, but once they have agreed to the media type then only the tcp 
connection will be there over which chunk of data will be passed. In this 
case you require to use the parsers processing the SIP headers initially 
only, just like any other RTP request,  but later we will just have data 
sent over a tcp connection.

>(Actually the way it seems to be going now is that INFO is so generic >that 
>There are other advantages of using a different method (one is proxies >who 
>do not support IM can simply return "Method not supported" >whenever a 
>MESSAGE comes across, instead of

Sir, It can de detected otherwise also by seeing the m= line in the session 
description. Okay ur right that with the MESSAGE header it will be 
instantaneous but don't u think that things like 'chat' can be handled at 
the SDP level(with TCP) rather than increasing complexity at the SIP level
In the instant messaging case a text/plain message will always be 
accompanied by a MESSAGE method (Please correct me if i'm wrong). So in this 
scenario everytime we receive this request we need to do the whole SIP 
processing (like parsing, generating headers for 200OK etc..), but with the 
"m=text <port> tcp plain" line in SDP in an INVITE request will require the 
SIP processing(just like above) only initially but later no SIP processing 
is required and simple data will be sent over the tcp connection which has 
been established.
>Arjun
             Sir, Its just an idea which has cropped up in my mind and i 
feel u people are experienced enough to help me clear my views so please 
reply to my query.
     Thanking You,
      Rahul
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