Subject: [clue] negotiation between consumer and provider

From: Paul Kyzivat <[email-masked]>
Date: Thu, 31 May 2012 14:05:21 -0400

I just read through the three new drafts:

draft-pepperell-clue-switched-attribute
draft-hansen-clue-consumer-layout
draft-romanow-clue-audio-rendering-tag

All three of these propose a mechanism that, AFAIK, is new to CLUE:
it is that data included by the consumer in its selection message to the 
provider might alter in a fundamental way what content is included in 
the selected captures. More specifically, its proposed that the consumer 
describe something about its use of the captures, and that then the 
provider will tailor what is sent in the captures.

This seems to be a change from the model that has been previously 
discussed - the three message exchange: 
capabilities/advertisement/selection. As I understand that model, the 
provider can use the capabilities from the consumer to tailor what it 
advertises to the consumer, and then the consumer selects from what has 
been advertised.

ISTM that its intrinsic in the selection process that the captures that 
have been advertised have some specific semantic that is preserved when 
they are selected. This new model seems to alter that relationship. I 
don't mean to imply that it is wrong, only that it seems like a 
fundamental change.

It also seems to me that at least part of what has been proposed in 
these drafts could be addressed by the prior model - especially since 
the content of the capabilities message is yet to be defined. For 
instance, If the consumer were to specify that it has three screens and 
a speaker with each screen, then an MCU as provider could construct an 
advertisement containing a single scene where all the entries contain 
three captures. These would presumably be alternative ways of rendering 
the conference on three screens. It wouldn't require the consumer to 
again decide its capabilities as part of the selection. I think it might 
also increase the likelihood that the MCU could reuse the same captures 
it provides for more than one endpoint.

	Thanks,
	Paul (as individual)