Re: [Sip] querying the current event state of a publication

inline.

Paul Kyzivat wrote:

>> If we want this functionality, I have an idea for an alternative 
>> approach that works much better, triggered by some conversations I had 
>> with Ben C. recently.
> 
> 
> That's a big IF. Do we really want to mandate that every compositor must 
> be prepared to provide this? It certainly puts contraints on the 
> implementations, and in most cases I think publishers can be constructed 
> so that they don't need this capability.

The main constraint I think it introduces is that the compositor needs 
to keep around the presence documents from each individual source, in 
addition to the final result of composition. I am not sure if this is 
new; I don't know how it couuld do composition without keeping these 
around.

> 
> I think the only time you might need this event state is when partial 
> publication is in use and the publisher has forgotten the full state, 

Yes, I agree this is one possible use case.

> or 
> when a backup publisher is trying to pick up from another one. In the 
> former case, there is no real advantage over simply transmitting the 
> full state as a refresh - same amount of data is required.

A fair point.

> 
> The advisability of supporting the latter case seems questionable to me. 
> There is a lot of work in providing a real failover backup, and it might 
> as well include remembering the state locally. If this capability is 
> provided we run the risk of abetting the construction of dualing 
> endpoints competing to publish particular event state.

I think that is a consequence of a backup takinig over publication for 
a primary, not a consequence of reading the current presence state or not.

> 
> But, if in the end there is a good argument for this capability, then 
> the proposal for how to do it seems reasonable.

My suggestion was mostly along the lines of - this is a good way to do 
it, rather than, we should have this feature. I recall there was a 
3gpp requrement for it, and  I remember asking why it was there, and I 
dont remember the answer, in fact.

-Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.                600 Lanidex Plaza
Chief Technology Officer                    Parsippany, NJ 07054-2711
dynamicsoft
jdrosen@dynamicsoft.com                     FAX:   (973) 952-5050
http://www.jdrosen.net                      PHONE: (973) 952-5000
http://www.dynamicsoft.com

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