[OpenSIPS-Users] SIP Presence Aggregation Issue

[Anca Vamanu]

Hi all,

This mail is a request for your comments about presence aggregation. 
What is your opinion about this? Do you consider it to be a real problem 
and which could be the solutions?

Although it is possible to have more clients registering for the same 
account and publishing presence information, there are not so many 
clients ( none that I know of in fact ) that are able to show more than 
one presence state per buddy. So, even if the presence server does 
aggregate all the presence information for a contact and sends it to its 
watchers, they will see only one presence state, most likely the one in 
the top most record.
Therefore, if a contact is registered on three sip clients and two have 
the status 'open' and third has 'closed', if it happens that the 
published information from the third phone is first in the aggregated 
body, its watchers will think that the contact is not online. More than 
this, the logic in OpenSIPS presence server at this moment, orders the 
records after the criteria 'newest info first'. This means in fact that 
if you have a buddy with more phones registered and different states set 
on them, you will see a continuous switch of states, depending on which 
phone updated the publication last ( not only at status changes, but 
also for expires refresh).

In consequence, since the clients are not able to interpret the 
aggregated information correctly, we raise the question whether it is 
useful to have more intelligence in the presence server. Instead of 
merely concatenating the published info and ordering it after the 
criteria 'newest-first', maybe we should analyze those contents and 
decide which is the most important and should be placed first. What 
precedence rules should we consider in this case? If one contact is 
'open' probably the first tuple should be open, but how should we deal 
with substatuses? Should we concatenate them all? Or maybe we should 
permit users to define priorities for the contacts of their phones in an 
web interface for example, and use those priorities to order the 
presence information. Are there other solutions?

We are interested to know your opinion about this subject.

Regards,

-- 
Anca Vamanu
www.voice-system.ro