There can be several UPDATEs with their associated 200-UPDATES before
the 200-INVITE.
Remember that UPDATE is a nonINVITE transaction and there may be a
_long_ time between the UPDATE and the 200-INVITE.
Paul drew the arrow backwards for the 200-UPDATE though - did that
mislead you?
RjS
On Nov 21, 2007, at 7:02 PM, Dean Willis wrote:
On Nov 21, 2007, at 5:15 PM, Paul Kyzivat wrote:
That may seem simple and harmless. But it gets ugly when
additional offer/answers happen:
Alice Bob
| INVITE offer1 |
|----------------->|
| 183 answer1 |
|<-----------------|
| PRACK |
|----------------->|
| 200 PRACK |
|<-----------------|
| UPDATE offer2 |
|<-----------------|
| 200 UP answer2 |
|<-----------------|
| 200 IN SDP? |
|<-----------------|
Now what should be in the 200 for the invite?
Its better to do what is already required - send no SDP in the 200
for the invite.
Huh. Is it actually ok to send a 200 OK for the UPDATE before
sending the 200 OK for the INVITE? That seems like a race condition
from hell.
If it's OK only because you can claim the INVITE's O/A sequence
completed before the UPDATE was sent, then we're making the SIP
state machine dependent on the O/A model, and that's just wrong.
--
Dean
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