[Standards-JIG] RE: Jingle channel naming (was Jingle schema extensibility)

Joe Beda jbeda at google.com
Wed Apr 5 17:12:28 UTC 2006

Here are some proposed changes to address these issues:

1) Earlier we decided to allow multiple <description/> elements to be active
at the same time.  This allows us to add whiteboarding to an audio session,
for instance.  One thing that we didn't talk about is allowing multiple
descriptions of the same *type* (namespace) to be active at once.  To allow
this we should my add a description id (did) to each description element.
It might look something like this:

<jingle type='inititate' sid='sid-0' ...>
  <description xmlns='desc-ns-0' did='did-0'>...</description>
  <description xmlns='desc-ns-0' did='did-1'>...</description>

In this way the user can accept/reject either of these and we can identify
them from each other.  There should also be a way to specify which
description a 'session-info' message is sent to.

2) We still only have one and only one transport negotiated per session.
That transport should be able to support multiple channels.
3) A channel is changed to be defined as "An abstract way to get a stream of
data packets from one description to another.  The transport is not required
to be reliable or to preserve order."
4) A channel is identified uniquely by the tuple (<channel id>,<description
id>).   (I'm renaming the channel name attribute to "channel id" or 'cid'
for short).
5) The requirement for a channel is defined by the description.  This could
either be done staticly in the JEP for the description (say voice always
uses a cid of 'voice-rtp') or could be done dynamicly by the description.

Adding this in, we would end up with something like this.  (Assuming that
the 'desc-ns-0' description statically requires a channel with cid='cid-0')
<jingle type='inititate' sid='sid-0' ...>
  <description xmlns='desc-ns-0' did='did-0'>...</description>
  <description xmlns='desc-ns-0' did='did-1'>...</description>
  <transport xmlns='trans-ns-0'>...</transport>

Negotiation of channels happens via transport-info messages:
<jingle type='transport-info' sid='sid-0' ...>
  <transport-info xmlns='trans-ns-0'>
    <candidate cid='cid-0' did='did-0' .../>
    <candidate cid='cid-0' did='did-1' .../>

Does this make any sense or are we just missing each other? :)

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