29 Sep
2011
29 Sep
'11
11:05 a.m.
Hey Jason,
On 29.09.2011 16:54, Jason Penton wrote:
Awesome, thanks Timo. However, The example you give
here is to store
dlg_cell in transaction. Actually, we are using the reverse, se pseudo
code below:
when INVITE req_forwarded callback is called, create dialog_in
structure, link and store pointer to transaction in dlg_cell
if we get a request to terminate dialog that is unconfirmed we get the
transaction ptr from dlg_cell and traverse through branches, sending
fake_reply (480/408/x).
Dialogs aren't stored in transactions, they are stored (hackishly) in
transaction callbacks (better: attached to them). But anyways, I think
the uses-relationships are similar in both cases: The dialog module is
called and needs to refer to its transaction. The current module's
pseudo-code:
"When INVITE on_create callback is called: create dialog structure, link
and store pointer to transaction in tm callback.
If we a response, fetch the transaction ptr from the tm callback to
allow access to dialog variables."
AFAICS, all that differs is the location of the transaction pointer
which is currently stored in a tm callback (bad) while you use the
dialog structure (good). Let me know if I get things wrong.
Cheers,
--Timo
On Thu, Sep 29, 2011 at 4:34 PM, Timo Reimann
<timo.reimann(a)1und1.de
<mailto:timo.reimann@1und1.de>> wrote:
Hi Jason,
On 29.09.2011 16:06, Jason Penton wrote:
Ok Dialog2 progressing nicely. We now have
dialogs and their
associated
out dialogs (branches / forking) stored and
managed within the dialog2
module. For the moment, we have excluded DB support but will add
once we
check in to git. One thing we need a little
assistance with:
We have just finished the prototype for proxy initiated early dialog
termination, but we are concerned with the way it has been done.
Basically as mentioned in the wiki
(http://www.kamailio.org/dokuwiki/doku.php/modules-new-design:dialog-module-…),
*
It should be possible to terminate dialogs in the “early” state,
i.e., sending out BYE/CANCEL requests in order to terminate all
branches appropriately.
o
ibc: IMHO it would be easier just to cancel the
transaction
as when fr_inv_timer expires, this
is, by sending a CANCEL
to all the pending branches and a 408 to the UAC
(perhaps in
this case a 480 would be more
appropriate).
The only way we could think of doing this was to send a fake reply via
the TM module. We have therefore exposed the fake_reply function from
the TM module and using that to terminate early dialogs. It works
in the
test scenarios we have performed, but the main
drawback we can see
here
is that the dialog module needs to hold a pointer
to the
transaction for
each dialog (not sure how bad this is as my
experience with tm is not
expert yet ;) )
So any thoughts/ideas. Is this the correct way to do it? Would it be
okay to expose a fake_reply function through TM API?
I cannot comment on how good or bad it is to expose the fake_reply
function.
Regarding pointing each dialog to its associated transaction at a given
time: This is already implemented in the current dialog(1) module. It
was needed for several reasons, one of them being to allow access to
dialog variables in responses. The way the link between dialogs and
transactions is done is by attaching a transaction pointer to the
TMCB_MAX callback which is fetched when required. Look at
store_dlg_in_tm() in dlg_handlers.c and get_dialog_from_tm() in
dlg_profile.c.
Yes, abusing TMCB_MAX to store additional data is kinda hackish. The
point here is that the dialog/transaction linkage is definitely needed,
so IMHO you may go ahead and re-establish it in dialog2. Finding a
cleaner implementation approach that doesn't involve TMCB_MAX is highly
appreciated though.
HTH,
--Timo