January 2016
Intermediate to advanced
384 pages
8h 6m
English
book
Building Telephony Systems with OpenSIPS - Second Edition
by Flavio E. Goncalves, Flavio E Goncalves, Bogdan-Andrei Iancu
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Handling the CANCEL requests and retransmissions
A CANCEL method is used to cancel a request in the early state. According to RFC 3261, CANCEL requests need to be routed in the same way as INVITE requests. The following script checks whether CANCEL matches an existing INVITE transaction and takes care of all the necessary routing. Sometimes, we have retransmissions associated with an existing transaction. If a retransmission is detected while the system is still processing the original request, the t_check_trans() function will discard it.
#CANCEL processing
if (is_method("CANCEL"))
{
if (t_check_trans())
t_relay();
exit;
}
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.