RE: [XCON] Control Values and the Data Model

["Brian Rosen" <br at brianrosen.net>]

I think I understand Adam's concern.  If the conference state is represented
by the conference object, then the template part of the object needs a
branch for every participant (in the role) so that an authorized entity can
read or set the value of Bob's gain different from Alice's gain.  Sure, Bob
may only see his own value, but the moderator may be able to see everyone's.

I think this is pretty much tied to the protocol.  The protocol can have a
concept of a complex key (user+device+control), which doesn't imply that the
object itself has branches for user and device.

As I said in a previous message, I'm not so sure now, having reflected on
the subject, that getting away from the central notion that the conference
state is defined as an object with a schema that is part common and part
template, and manipulating conference state is directly manipulating said
object is a good idea.  The "functional" protocol idea DOES get away from
that notion; it imposes a different view of conference state which is not
the conference object and provides methods that act on that view.

If we were to get back to that notion (conference state = object state),
then the object would indeed need branches for user and possibly device,
which would change the template definition.  We could then argue whether it
was user.device.control or control.user.device (that is, which are the
leaves and which are the main branches of the tree?)

I don't think putting the controls into the common part of the object (which
does have participant branches) is wise.

Brian

-----Original Message-----
From: Chris Boulton [mailto:cboulton at ubiquity.net] 
Sent: Wednesday, May 03, 2006 12:51 PM
To: Adam Roach; XCON-IETF
Subject: RE: [XCON] Control Values and the Data Model


	Now, here's the interesting issue: where, if anywhere, does this
	document represent what the specific value for Bob's gain for
his
	AudioOut channel is?

[CJB] Adam - I'm a bit confused (doesn't take much :-).  This is taken
from the 02 version of the templates
(http://www.ietf.org/internet-drafts/draft-boulton-xcon-media-template-0
2.txt): 


<stream type="audio" name="AudioOut" dir="out">
                          <control type="real" name="gain" enable="true"
>
                            <label>Volume</label>
                            <value>1.0</value>
                           </control>
                         </stream>

As you can see we had a 'value' element that represents the gain.


	It can't go in the Template portion, since the template has
      entries for each role, not for each user. In other words, it has
      precisely one "Participant" section, even though there can be
      multiple participants.

[CJB] But each participant will have a relevant view of the template -
indicating there own particular gain.  The Conference server will have a
view of all participants and there relevant conference view.

Chris.


-----Original Message-----
From: Adam Roach [mailto:adam at nostrum.com] 
Sent: 03 May 2006 00:21
To: XCON-IETF
Subject: [XCON] Control Values and the Data Model

In a recent discussion that the XCON operations document editors were
having, an interesting issue arose. It's not clear to me that we have
given a lot of thought to this issue, so I'd like to see what opinions
the working group has on the topic:

The current view of the data model as described in the framework is that
we have a common conference portion (based primarily on the schema given
in draft-ietf-sipping-conference-package-12); and we have a template
portion (such as those described in
draft-boulton-xcon-media-template-02).

Eliding a lot of information, this leads us to a breakdown of
information roughly along the lines of:

<!-- COMMON PORTION -->

<conference-info>
  <users>
    <user entity="sip:bob at example.com">
      <roles>
        <entry>participant</entry>
      </roles>
      <endpoint entity="sip:bob at 123.45.67.8">
        <media id="1">
          <type>audio</audio>
        </media>
        <media id="2">
          <type>video</audio>
        </media>
      </endpoint>
    </user>
  </users>

<!-- TEMPLATE PORTION -->

  <template name="basic-audio-video">
    <role name="participant">
      <stream type="audio" name="AudioIn" dir="in">
        <control type="boolean" name="mute" enable="true">
          <label>Mute-Audio</label>
        </control>
      </stream>
      <stream type="video" name="VideoIn" dir="in">
        <control type="boolean" name="pause-video" enable="true">
          <label>Pause-Video</label>
        </control>
      </stream>
      <stream type="audio" name="AudioOut" dir="out">
        <control type="integer" name="gain" enable="true">
          <label>Volume</label>
        </control>
      </stream>
      <stream type="video" name="VideoOut" dir="out" />
    </role>
  </template>
</conference-info>



Now, here's the interesting issue: where, if anywhere, does this
document represent what the specific value for Bob's gain for his
AudioOut channel is?

With the current structure:

    * It can't go in the Template portion, since the template has
      entries for each role, not for each user. In other words, it has
      precisely one "Participant" section, even though there can be
      multiple participants.

    * It can't go in the Common portion, since that part of the document
      is defined to not change regardless of the template in use.
      Because of this, I don't think we can start putting control values
      specific to the template up there.

I can think of two ways to handle this, although there may be more:

   1. Add yet another section to the document, associated with the
      template part, that basically forms the cross product of each user
      and their relevant controls. In other words, add a section like:

      <conference-info>
      ...
        </template>
        <control-values>
          <endpoint entity="sip:alice at 123.45.67.7">
            <control stream="AudioOut" name="gain" value="92" />
            <control stream="AudioIn" name="mute" value="false" />
            <control stream="VideoOut" name="pause" value="false" />
          </endpoint>
          <endpoint entity="sip:bob at 123.45.67.8">
            <control stream="AudioOut" name="gain" value="92" />
            <control stream="AudioIn" name="mute" value="false" />
            <control stream="VideoOut" name="pause" value="false" />
          </endpoint>
          <endpoint entity="sip:charlie at 123.45.67.9">
            <control stream="AudioOut" name="gain" value="92" />
            <control stream="AudioIn" name="mute" value="false" />
            <control stream="VideoOut" name="pause" value="false" />
          </endpoint>
          <endpoint entity="sip:dinah at 123.45.67.10">
            <control stream="AudioOut" name="gain" value="92" />
            <control stream="AudioIn" name="mute" value="false" />
            <control stream="VideoOut" name="pause" value="false" />
          </endpoint>
        </control-values>
      </conference-info>

   2. Don't include the literal control values in the document. Instead,
      clients can use the list of user devices and the roles associated
      with them to ascertain which controls are valid for which
      user/endpoint/media-stream combination. Then, the control values
      could be explicitly queried and set by the operations protocol. As
      an example, the XML document representing the conference state
      would never include the value of my "gain" control -- but you
      could learn what it was by issuing a command that basically said
      "query user=sip:adam at estacado.net, device=sip:adam at 123.45.67.8,
      stream=AudioOut, control=gain".


Thoughts?

/a

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