Subject: SIP, inconsistency in revised version.

From: Lars Berggren <[email-masked]>
Date: Mon, 13 Sep 1999 12:02:34 +0200

Quoting from section 4.2.5 in the revised version of the spec,
http://www.cs.columbia.edu/~hgs/sip/drafts/draft-ietf-mmusic-sip-new-00.pdf
:

"Once a user agent server has received a CANCEL,it MUST NOT issue a 2xx
response for the cancelled original request. Instead, it issues a 487
(Request cancelled) response immediately upon receipt of the CANCEL
request."

and a few lines down :

"If the CANCEL request terminates a pending request, the server SHOULD
NOT send a final response for the request that was canceled."

I assume the 487 response is sent in response to the 'cancelled original
request'. With this assumption made, I can't see any logic here, just a
total contradiction, since the first quote says that a final response
should be sent and the other says not.

Explanations/arguements are welcome. I think the sending of a 487
response would be the nice thing to do for user agent servers, since it
will help transactions to complete faster.

Anyway, I think it doesn't break the protocol if implementation A sends
final responses when cancelled and implemention B doesn't, since in
either case the cancelled transaction fails. But, the contradiction
confuses the reader.

/Lars

-- 
Lars Berggren       <[email-masked]>
Intertex Data AB    tel: +46-8-6282828
Sundbyberg, Sweden  fax: +46-8-6286414

---

From: Henning Schulzrinne <[email-masked]>
Date: Mon, 13 Sep 1999 08:20:36 -0400

> NOT send a final response for the request that was canceled."

Unless I'm missing something subtle, the second sentence is just a
remnant of the pre-487 behavior and should be struck. Any objections? 

-- 
Henning Schulzrinne   http://www.cs.columbia.edu/~hgs