18 Jan
2003
18 Jan
'03
1:58 p.m.
On 17-01 13:44, Maxim Sobolev wrote:
Well, since some entity (B2B UA) will have to maintain call state
anyway, this will only move botleneck to that entity, not eliminate
it. Therefore, I don't see why introducing that another entity and
additional level of indirection associated with it, when it is
possible to do it right in the proxy. After all, I am planning to do
it as a module, so that if somebody doesn't need this functionality he
will not load the module and have the full raw power of the ser at his
hands.
Sure, you cannot eliminate the bottleneck but at least you can move it
to another entity which could be optimized as B2BUA, this is not true
for ser. It is not possible to do really good implementation of B2BUA
in ser, but nothing prevents you from implementing a module doing that as
long as it doesn't require significant changes to other parts.
I disagree - who prohibits you to send two BYEs to both parties once
the timer is expired impersonating itself as UAS for one party's UAC
and UAC for another party's UAS? Since you was in the middle of the
call flow, you obviously have every piece of information necessary for
doing it.
As I have told you, you will need a B2BUA to implement this. ser is a
proxy and many features that a user agent has to do are missing there.
If you are looking for a hack that will be able to terminate a call only,
that should be possible, but I personally don't like it, in my opinion ser
should stay transaction-stateful only, dialog support and things that use
it will only bloat it. We will probably distille dialog support and code
that will use it from ser in the future.
regards, Jan.
Jan Janak wrote:
Not yet, I will put it in the CVS once I make sure that it works as expected.
Hello,
comments inline.
On 16-01 23:37, Maxim Sobolev wrote:
Is it in cvs? If not, how can I obtain it? Hi,
I am thinking about writing a new module for SER, which will track SIP
dialogs and will serve as an abstraction layer for other modules, much
like the tm module now. We need such module for 2 reasons:
We are working on dialog support. It is working already but still
not mature enough to release. 1. Call accounting. Our billing engine is based on the
assumption that
a node provides accounting information for completed calls, not for
individual transactions. It is easier for us to extend proxy with
similar features than to modify billing engine to do transaction
matching.
You can match the INVITE and BYE transactions and you have the whole
call. IMHO it is easier to modify billing software to do this than
implement it in the proxy.
From my point of view, dialog support in a proxy should be avoided
wherever possible. The dialog support includes some additional bottleneck
to the proxy. The proxy must maintain dialog state for the duration of
the call and that can be very memory intensive. Our tests show that even
transaction state can exhaust memory of an extremely loaded proxy in less
than a minute. 2. Debit card application. Currently, there is no way
to use SER for
debit card applications, where it is necessary to set the maximum
duration of the call and terminate it forcefully if that duration is
exceeded.
Yes, there is no way to do it, that's a feature, not bug. Dialog support
is not enough to make this possible. To be able to terminate a call, you must
implement a back to back user agent. A back to back user agent is an entity
that maintains two dialog states and acts as a UAS on one side and UAC on
the other. That means it terminates calls on one side and initiates call
on the other side. So even if you had dialog support in ser, you would be
unable to terminate calls.