-------- Original-Nachricht --------
Datum: Thu, 16 Aug 2007 09:53:04 +0200
Von: Olaf Bergmann <Olaf.Bergmann@freenet-ag.de>
An: cherami@gmx.de
CC: serusers@lists.iptel.org
Betreff: Re: [Serusers] presence server 2 presence server

cherami@gmx.de wrote:
> Hi,
>
> I am student and new to the Presence Model und Protocols.
>
> I have in my student project the following scenario:

So, one task in this project would be to figure out the details by
yourself, right? As a starting point, you should gather some
material about distinct presence protocols and learn how these
protocols work·

> company A wants to develop a presence service PA. The presence service
> PA should get the data from the presence server PB of an other Company B
> over the Internet. The Presence information of PA should be made
> available in the Company A for different applications.
>
> my question:
> can PA poll or subscribe all changed/updated Presence Information from
> PB regularly. Or it should request the Presence Information of each
> Presentity individually?

Most "real" presence protocols such as SIP-based presence (sometimes
referred to as "SIMPLE") and XMPP at least allow for individual
subscriptions as well as so-called subscriber lists.

One of the problems with this kind of application is the overhead
>from presence messages, especially when using SIP. Therefore, XMPP
might be a better choice for your specific application since it can
provide for confederations of presence servers over a more efficient
communication channel.

> which Presence server can implement the presence service PA.

SER could do this for SIP-based presence (including resource
subscription lists), ejabberd could be used for XMPP.

> What should I do if PB uses another Protokoll?

You would have to use a protocol gateway. Look at the
presence-related SER documentation to learn how this works.

HTH,
Olaf