[Serusers] presence server 2 presence server

Olaf Bergmann Olaf.Bergmann at freenet-ag.de
Thu Aug 16 09:53:04 CEST 2007


cherami at 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



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