[SR-Users] Transaction good practices with t_relay t_newtran and t_release

[Alex Balashov]

There are really no healthy applications of Kamailio in which processing of a request should take a long time, due to Kamailio's limited number (necessarily so) of SIP worker threads. So, the temporal delta from initial message receipt to t_relay() should not be high, and once t_relay() is called, a transaction is created anyway, allowing you to dampen retransmissions with t_check_trans() & friends.

If you must use high-delay processing, use of the TM async capabilities is highly recommended. The suspend/continue required to shuttle request processing off to another thread does require explicit transaction creation up-front, true enough. However, most retransmissions can be dampened by preemptively sending a stateless 100 Trying first.
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Alex Balashov | Principal | Evariste Systems LLC
303 Perimeter Center North, Suite 300
Atlanta, GA 30346
United States

Tel: +1-800-250-5920 (toll-free) / +1-678-954-0671 (direct)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/

Sent from my BlackBerry.
  Original Message  
From: Mickael Marrache
Sent: Thursday, April 30, 2015 04:32
To: 'Kamailio (SER) - Users Mailing List'
Reply To: Kamailio (SER) - Users Mailing List
Subject: Re: [SR-Users] Transaction good practices with t_relay t_newtran	and	t_release

Hi,

I think one would like to create transaction ASAP to absorb retransmissions.
In some scenarios, processing a message can take time and retransmissions
are likely to happen, and you don't want the retransmissions to be processed
again (which can lead to errors in some scenarios). t_relay is generally
called at the end for relaying the message.

Mickael

-----Original Message-----
From: sr-users [mailto:sr-users-bounces at lists.sip-router.org] On Behalf Of
Alex Balashov
Sent: Thursday, April 30, 2015 11:26 AM
To: Dirk Teurlings - SIGNET B.V.
Subject: Re: [SR-Users] Transaction good practices with t_relay t_newtran
and t_release

Dirk,

Why do you need to create new transactions yourself with t_newtran()?
Nonexotic applications of Kamailio usually don't require this. A transaction
is automatically created after t_relay() is called, and its lifecycle is
automatically managed - including destruction - based on the replies
received to the transaction-forming request, and based on RFC 3261 rules in
cases of timeouts.

--
Alex Balashov | Principal | Evariste Systems LLC
303 Perimeter Center North, Suite 300
Atlanta, GA 30346
United States

Tel: +1-800-250-5920 (toll-free) / +1-678-954-0671 (direct)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/

Sent from my BlackBerry.


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