[JDEV] TINS - SDPng

Sat Jul 26 12:12:46 CDT 2003

These are the documents I've familiarized myself with ---

related to TINS - Transport for Initiating and Negotiating Sessions (using 
SDPng over XMPP)
http://www.ietf.org/internet-drafts/draft-hildebrand-xmpp-sdpng-00.txt

related to SDPng - Session Discription Protocol negotiation
http://www.dmn.tzi.org/ietf/mmusic/sdp-ng/
http://www.dmn.tzi.org/ietf/mmusic/sdp-ng/drafts/draft-ietf-mmusic-sdpng-06.txt

--- the TINS document gives an example which I'm hoping I can copy and put 
to use. I've pasted the opening message from the example below, I see two 
possibilities, one is that I don't send the message until I want to have my 
contact handle some sort of media that is separate from the normal text 
message, the other alternative is that I automatically initiate discovery of 
the contact's capabilities as soon as possible. It seems to me that to 
conserve bandwidth there is little need to discover all the capabilities if 
all that you are going to do is type "Hi, home at 5" or something. If one 
has 100 contacts things could be more cluttered than there is a need to 
have.

On the other hand, a lot of the SDPng documents seem to refer mostly to 
conferences. In those circumstances the discovery of all of a clients 
capabilities and agreement on the final configuration may be necessary right 
from the start.

The example below seems to be from contact to contact, I think (but that 
<conf> tag makes me doubt myself). It seems I would just send Contact A a 
message with a <tins> element embedded. The tins element has a method 
'INVITE'. From reading the document I see there are two other possible 
methods of the tins element 'ACK' and 'BYE'.

I note that the example message's body element has the example text saying 
what it does, specifically "but your client does not support TINS". Does 
this mean that if I send a message to a TINS supportive client that the body 
of the message will not(must not?) be displayed, as it doesn't seem right to 
tell a client that does in fact support TINS when it doesn't?

Anyway, it appears that within the tins elements there are a number of child 
elements that use the 'http://www.iana.org/sdpng' namespace. These elements 
are <def><cfg>and <conf> ones. I guess I should read the documents again, 
I'm taking <def> to be "define", <cfg> to be "configuration" and <conf> to 
be "conference"?? Does that seem right?

For a start, I'd like to try something simple, like, I want to know if my 
contact can play an mp3 file and if so, send the client the url where the 
mp3 is available. Alternatively, can the contact play a wav file or a swf?

Does that seem like a valid use of TINS?

Greg.

(The example from the TINS document below)

<message from='A at example.com/work' to='B at example.com'>
     <thread>1234 at hostA.example.com</thread>
     <body>This message contains a TINS invite,
           but your client does not support TINS.</body>
     <tins method='INVITE'
       xmlns='http://www.jabber.org/protocol/tins'>

       <def xmlns='http://www.iana.org/sdpng'>
         <codec name="audio-basic" encoding="PCMU"
           sampling="8000" channels="1"
           xmlns='http://www.iana.org/sdpng/audio'/>
         <pt name="rtp-avp-0" pt="0" format="audio-basic"
           xmlns='http://www.iana.org/sdpng/rtp'/>
       </def>

       <cfg xmlns='http://www.iana.org/sdpng'>
         <component name="interactive-audio" media="audio">
           <alt name="AVP-audio-0">
             <session format="rtp-avp-0"
   		    xmlns='http://www.iana.org/sdpng/rtp'>
               <udp role="receive" endpoint="A" addr="192.168.1.1"
   	            rtp-port="7800"/>
             </session>
           </alt>
         </component>
       </cfg>

       <conf xmlns='http://www.iana.org/sdpng'>
         <owner user="A at example.com" id="98765432" version="1" nettype="IN"
                addrtype="IP4" addr="192.168.1.1"/>
         <session name="SDPng questions"/>

         <info name="interactive-audio" function="voice">
           Telephony media stream
         <info>
       </conf>
     </tins>
   </message>

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