[asterisk-users] rfc3680, reginfo+xml

[Raj Jain]

Olivier,

In principle, Registration/Presence and Call-Processing are separate logical
functions but for cost or other reasons one could combine them in one
software implementation or one physical box. For most parts, Asterisk is the
Registrar in a SIP network and therefore maintains the location table. So,
whatever entity runs the RFC 3680 notifier function will need access to
Asterisk's location table. This is not the real issue though (the access to
this table can be easily granted through the API). The answer to whether RFC
3680 should be built inside Asterisk or outside of it really depends on the
kind of scalability one is looking for. 

The scalability here refers to the number of subscriptions per each AoR
(notification fan-out). Basically, you don't want to overload Asterisk with
excessive number of subscriptions to the extent that they can negatively
impact call/media processing. If you compare this with presence, the PUBLISH
method allowed the presentity to inform only one entity (the presence
server) of its state changes. The presence server was the one that did the
drudgery of maintaining individual subscriptions and notifying the watchers.


The presence model assumes that there are multiple watchers subscribing to
the state of *a* presentity. RFC 3680 is a bit different than this, however.
If you are looking to do free-seating using RFC 3680, I'd imagine that you
will need only one subscription for each AoR in Asterisk (so you don't
really have a 1:n fan-out issue). In that case, it is probably okay if the
RFC 3680 'notifier' function was embedded within Asterisk itself. The
current RFC 3265 support in Asterisk code should make the job of supporting
RFC 3680 a bit easier.

Raj


________________________________

	From: asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Olivier
	Sent: Wednesday, August 22, 2007 8:27 AM
	To: Asterisk Users Mailing List - Non-Commercial Discussion
	Subject: Re: [asterisk-users] rfc3680, reginfo+xml
	
	
	Thanks for replying, Raj.
	
	Do you think such feature should, ideally, be implemented in
Asterisk should it be implemented in a dedicated software (presence ?) ?
	It seems to me it should, though I'm not aware of many devices using
this feature, beside SIP hardphones. 
	
	Would it be difficult to extend current code to comply with this
RFC, when rfc3265 mechanism is already in place ?