[Serusers] PA module status

[Jamey Hicks]

Dave Bath wrote:

> Hi list,
>
>
> I’m sorry to ask this to the list, as I’m sure I’ve seen the 
> information before but after some googling I can’t really find it. Can 
> anyone shed some light on the status of the presence module at the 
> moment? How far developed is it? Which methods does it now support? 
> Can people subscribe with their regular ser username? I know there’s 
> been some work on it recently, and any info would be gratefully received.
>
The PA module is still a work in progress, partly because the specs I've 
been implementing against are internet-drafts that are updated at least 
every 6 months, though "A Presence Event Package for the Session 
Initiation Protocol (SIP)" has been published as RFC3865.

PA handles subscribes on behalf of users registered against ser and 
generates notifies when their presence information changes. One source 
of presence information is usrloc/registrar but PA also handles PUBLISH 
messages from UAs. PA is able to composite event state from multiple 
user agents. For presence information, PA generates NOTIFY messages with 
lpidf, xpidf, or the preferred pidf format. For authentication of 
subscribers, PA generates watcherinfo notifications so that the UA can 
use XCAP to fetch and update watcher authentication documents. I have 
written a rudimentary XCAP server in python that I believe is available 
from pals.internet2.edu.

In addition to PIDF, it supports extended status, prescaps, and 
geographic or civil location.

PA does not subscribe to presence information -- it only uses the local 
registrar and incoming PUBLISH messages as a source of presence state.

We've been using it in the Internet2 Presence Integrated Communication 
working group since last January. It mostly works but is not as stable 
as it should be. Jan Janak found and fixed a race condition but that 
code has not been tested extensively and is not yet in CVS.

Jamey