Re: [Sip] Open Issue #7: CANCEL for non-INVITE

Jonathan Rosenberg wrote:
[...[
> So, here is the first. Issue #7: CANCEL for non-INVITE.
[...]
> My proposal was that we should deprecate CANCEL for non-INVITE.

Jonathan:

If we have as a operating assumption (requirement?) that non-INVITE methods
have to be responded to immediately, then deprectaing CANCEL for these
methods is actually preferable.

Even in the SUBSCRIBE case you mentioned in your email, if the UAS fielding
the SUBSCRIBE "knows" that there maybe delay -- caused by ldap lookups,
user authorization, whatever -- in responding with a 200 OK to the 
SUBSCRIBE, it still must send a 202 Accepted final response right away.  So 
I see little utility in attempting to CANCEL a SUBSCRIBE.

As I pointed out at the London IETF, this issue is somewhat related to 
Issue #138 (to fork or not to fork [non-INVITE requests]).  Since the 
consensus on Issue 138 is that it is okay to fork non-INVITEs, -04bis 
should indicate (in Section 17.4, handling of 2xx responses) that a forking 
proxy need not CANCEL non-INVITE branches on getting a 200 OK for a 
non-INVITE request.

Regards,

- vijay
-- 
Vijay K. Gurbani  vkg@{lucent.com,research.bell-labs.com,acm.org}
Internet Software and eServices Group 
Lucent Technologies/Bell Labs Innovations, 2000 Lucent Lane, Rm 6G-440
Naperville, Illinois 60566     Voice: +1 630 224 0216   Fax: +1 630 713 0184

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