[Asterisk-Dev] Chan_sip version 1, 2 and NG: 3

[Olle E. Johansson]

Friends in the developer community,

I've hinted several times about chan_sip3. Let me explain what is going on:

chan_sip version 1 is what we have today. It's based on a peer/user
paradigm and made to work with local SIP phones attached more or less
directly to Asterisk.

As soon as you start adding a SIP proxy network, you see that this is
not what it was designed for. Try registering two accounts with the same
service provider and you will get very confused over all strange
settings you have to do to work around...

chan_sip2 was my old skunkworks project that got me started on SIP
development. A lot of untested patches was hanging around the bug
tracker and I compiled them all together to something that users could
test and started adding stuff to it. Most of these features are in the
current chan_sip in Asterisk 1.2.

chan_sip3 will be very much different. It will be based not on the loved
and hated peer/user paradigm, but on "phones", "services" and "trunks".
It will be a more complete SIP state machine with proper timers and a
better SIP parser and transaction/dialog handler. Hopefully, we will
have TCP/TLS and SRTP for this new channel.

In short, there's a lot of work ahead. We will start outlining the
requirements and visions in the coming weeks and then start ripping
chan_sip apart to build the new channel. This new chan_sip won't be
ready for release in 1.4, so I am targeting the release after that.
No details has been decided yet - whether we will continue with our own
parser or attach an external library, whether we will write in plain C,
APL, visual C# or C++... Well, guess the latter decision has been made :-)

In parallell, we will continue to fix bugs and make the current chan_sip
better, but there will be no major architecture or code structure
changes to the current chan_sip. So yes, committing patches to chan_sip
is still appreciated.

This is as much as I know now. As soon as we have some more notes
available on our vision for chan_sip3, we will publish it for review,
discussion and input.

/O