[osip-dev] Transaction handling overview, get-to-know help

[Máté Eckl]

Hi,

I am new to the mailing list, so I just introduce myself a bit. I'm
Máté Eckl a final-year BSc student in computer engineering at a
Hungarian university. I got connected to oSIP during my thesis which
is about the implementation of a passive VoIP probe, and I found the
oSIP library adequate to provide the SIP-related functionality.

I am relatively new to oSIP (and SIP either), and therefore I've been
going through the documentation found at
http://www.antisip.com/doc/osip2/modules.html.
I have a particular, and a more general problem, which I cannot solve
for some time.

The particular problem is that I followed the instructions at the
"How-To manage transaction", and the
osip_transaction_execute(transaction,se) causes a segfault. I
initialized either the transaction and se variables. Might have missed
to initialize some part of them? What should I check?


My general problem is that I don't really see through the mechanism,
of how a SIP packet should be processed with the oSIP library.
There is a How-To about transaction handling, but it does not
describe, how the steps should be connected.
In my understanding so far, an event is the arriving or sending of
sole SIP messages that has to be added to a transaction which is the
group of all the messages related to a request. If it is true, then at
this level I do not really understand why the transaction FIFO is
necessary, and how it should be handled. So why is it necessary to put
events in a FIFO and then just fetch them in a different thread (it
was not really clear, but the thread exit functions are suspicious).
Why is it not possible or advised to simply identify the relevant
transaction to make the state machine change move if necessary and
fire the registered callbacks? I suppose that as transactions are
relatively short life-time entities, the queried FIFO will change
frequently.

What I am now trying to do now is gathering information about a single
transactions following each other.

Thank you for the response in advanced.

Regards,
Máté