Hi Olaf,
I understand that a client must/can subscribe to an other client to get notifications of his status.
But can a presence server do something like that? Can a presence server subscribe to other clients?
The Idea is, that I have in my organisation Clients, that only needs the presence information of other clients in other organisations. So I want to cache/mirror in my server the presence information ot the clients ot the other organisation, so that I do need to connect the server ot the partners for each request from the clients of my organisation.
Best Regards Koder
-------- 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