[Standards-JIG] XEP-0155: do we need it?

Peter Saint-Andre stpeter at jabber.org
Thu Nov 9 21:41:23 UTC 2006

OK, now that XEP-0155 (Chat Session Negotiation) is in Last Call, I've
come to wonder: do we really need it?

One of the main use cases people have in mind for XEP-0155 is enabling
text chat between XMPP users and SIP users. I would imagine that the
protocol spoken by the SIP endpoint will be MSRP once that's all worked out:


But from the SIP perspective, MSRP is just another out-of-band media
session (a la RTP). Now, in order to negotiate a voice or video session
from an XMPP endpoint to a SIP endpoint, we'll use Jingle. So it seems
odd to use something different (XEP-0155) when negotiating an MSRP
session. For MSRP negotiation we might do something like this in Jingle:

<iq from='romeo at montague.net/orchard'
    to='juliet at capulet.com/balcony'
  <jingle xmlns='http://jabber.org/protocol/jingle'
          initiator='romeo at montague.net/orchard'
    <content name='this-is-some-MSRP-session'>
      <description xmlns='urn:xmpp:jingle:description:textchat'>
      <transport xmlns='urn:xmpp:jingle:transport:xmpp'>
      <transport xmlns='urn:xmpp:jingle:transport:tcp'>

And then off we go to negotiate the session.

Naturally we'd need to define the relevant content description format
(text chat) and perhaps some transport methods (another XMPP endpoint
would choose the xmpp method, a SIP/MSRP endpoint would choose tcp, udp,
or sctp). But at least this way we don't have two different ways of
doing what's the essentially the same thing.



Peter Saint-Andre
Jabber Software Foundation

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