[Asterisk-Dev] presence and IM again, want to develop a working "hack"

[Juraj Bednar]

Hello,

   I was again asked to try to add support for presence
(SUBSCRIBE/NOTIFY) and IM using SIMPLE. I have few questions:

   a.) are there any, at least partial projects, patches, anything,
that at least partly implements presence and/or IM to chan_sip? I
don't care about presence on other channels, I have one SIP client per
user. I've read this list's archive several times and found lots of
wonderful proposals, which try to convince asking users, what needs to
be done to support this well (multichannel, multiple phones per user,
...), mainly saying, that without very difficult reworking of
internals, it would not be supported. What I really need is to hack it
into chan_sip.c. I need the support of other channels and applications
(f.e. MeetMe), but where I really care about presence and IM is SIP.

   So, any project, hack, patch, anything, that would allow me to go
further with this would be greatly appreciated. I found this page in
Russian: http://www.asterisk-support.ru/forums/development/53843189454
that somehow deals with the problem. I tried babelfish translation,
(http://babelfish.altavista.com/babelfish/trurl_pagecontent?lp=ru_en&trurl=http%3a%2f%2fwww.asterisk-support.ru%2fforums%2fdevelopment%2f53843189454)
but I was not able to find out, if it really at least partially solves
this problem, but as far as I understand it, Windows Messanger makes
use of Subscribe/Notify, so this should be it.

  b.) Anyone has a partial solution using SER (which supports presence
and IM) as a frontend, but routing all calls through Asterisk? Can
this be done? I need the calls to go via Asterisk (I don't mean only
sip notifications, but also the data, so I have canreinvite=no). So
basically, SER would be a registrar "proxy" to Asterisk, which would
do the authentication. The only thing, that SER would do would be to
handle presence and IM and pass everything else on to Asterisk (as far
as I know, SER can't pass traffic through it. I need the data to pass
through the SIP server, since machines in my network topology don't
see each other, it's a star with Asterisk in centre -- quite poetic
indeed:). Any ideas, pointers to similiar configurations, ... are
welcome.

  c.) If there is no solution to start with, is it possible to
implement it only to chan_sip? I'm not familiar with Asterisk source
code at all. Where are the places to look (in chan_sip.c) which are
best to hook this code. Again, any code, hints, etc. about the
structure of the source code are really welcome. Doing this in a clean
way (although it's a hack) so it can be reused by community as much as
possible is my intent. If anyone wants to help with the project by
donating coder's time, mail me off the list.

  I hope I'll be able to support presence for hardphones and Xten's
eyeBeam softphone in a few days with your help.


     Best wishes and thanks for any replies,

         Juraj.