Re: [Simple] Re: Presence Data Model: Overriding services (tuples)

[Jonathan Rosenberg <jdrosen at dynamicsoft.com>]

inline.

Paul Kyzivat wrote:

>  > In
>
> > such a case, there is simply no ability to override at all. The 
> > compositor would basically assume that each published service is 
> > separate and non-overlapping. If you want override, implement gruu.
>
>
> I don't follow you here. They can't be separate and non-overlapping 
> services because they all have the same conctact address. So the 
> compositor would be forced to either override, or somehow merge them.

Sorry, let me clarify.

When a compositor sees two services, it needs to decide whether or not 
they are describing the same service or different ones. This distinction 
is really only important in the absence of explicit composition policies 
defined by users/admins. Absent explicit policies, it allows us to have 
a simple default which says that separate services are reported 
separately and if you have two descriptions of the same service, you 
should pick the most recent one.

If you had explicit policies, you could direct the server to have one 
service overried another irregardless of the service URI.

So, my point was this. Again only thinking about the default policy in 
the absence of somethign explicit, here is the logic:

if(service A URI == service B URI) {

  if(service A URI == AOR) {

     service A and B are different services

  } else {

     service A and B are the same service

  }

} else {

     service A and B are different services

}

based on this logic, the compositor would then apply the default 
composition - which is that two descriptions of the same service are 
resolved by taking the most recent one.

That means that, if a user wants to override another publication and 
there is no ability to specify an explicit composiiton policy, the 
published contact URI would need to be the same and NOT be an AOR.

HTH,
Jonathan R.


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

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