> -----Original Message-----
> From: Anand Vasudevan [mailto:[EMAIL PROTECTED]]
> Sent: Monday, May 14, 2001 7:26 AM
> To: SIP implementors; 'Jonathan Rosenberg'
> Cc: Poornima Holla; Sunil Kumar T
> Subject: [Sip-implementors] FSM implementation issue..
>
>
> Hi,
> I believe,in SIP,almost all FSM implementations are
> Transaction based.And
> also,Jonathan's view of SIP transaction is,"each transaction should be
> completely independent of others"
The point of my comments is that there are two state machines at work. There
are transaction state machines, which deal with requests,responses, and
ACKs. Those should each complete normally. THere is also a "call state
machine", which is not explicitly spelled out, but which has at least two
states - in a call, and not in a call. A successful initial INVITE puts a UA
in a call. A BYE request has its own transaction, but also changes the state
of the call - to "not in a call".
>
> In a scenario where,User X sends INVITE to user Y,
> and immediately it sends BYE to Y to terminate the INVITE
> sent.(consider no
> Final response for INVITE is sent by Y at this time)
As Bob pointed out:
> The central point of "each transaction should be completed
> independent of
> others" is that all requests must be responded to and that the
> INVITE,Response,ACK transaction must be completed. Sending a
> BYE or CANCEL
> for a pending invite does not mean that the UAS does not have
> to send a
> final response. The UAS sends a 487 response to the INVITE
> and a 200 OK
> response to the BYE/CANCEL. The UAC expects a 487 (or other
> final response)
> and must ACK that response.
That is, the INVITE transaction does complete with a 487. That is now
spelled out very explicitly in bis-03.
>
> At Y's end,
> 1.How these two transactions(BYE & INVITE) can be independent
> to comply with
> Jonathans' comments?
>
> 2.Will not the FSM for BYE need to interact with INVITE
> transaction FSM?(I
> feel there are seperate FSMs running for BYE and INVITE)
Yes, there are two transaction machines - one for INVITE, one for BYE. They
don't interact. But, they both affect a common call state machine.
-Jonathan R.
---
Jonathan D. Rosenberg, Ph.D. 72 Eagle Rock Ave.
Chief Scientist First Floor
dynamicsoft East Hanover, NJ 07936
[EMAIL PROTECTED] FAX: (973) 952-5050
http://www.jdrosen.net PHONE: (973) 952-5000
http://www.dynamicsoft.com
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