Re: INFO

First, I agree 100% with what Adam has said.

I just wanted to comment on one issue which is peripheral to
the 
discussion of INFO but is directly relevant to the issue of
semantics of 
sip messages in general.

Hadriel Kaplan wrote:

> I agree with you, but that problem already exists
today.  There are plenty
> of cases where there are constraints on the combination
of method+mime that
> cannot be described with Accept and Allow headers. 
There are devices which
> won't accept Invites or re-Invites without
application/sdp, and there are
> devices which don't accept Options with mime types they
do accept Invites
> with, etc.  (You can call them broken I guess)  What
does it mean for an
> application/sdp mime body to be in a Message method, or
in a Bye?

To the last question, it first depends on what the
Content-Disposition 
is. In spite of Gonzalo's draft on the subject, most people
continue to 
ignore this. But it really needs to be a key part of
decision about the 
semantics of message bodies.

If an application/sdp body has content-disposition of
"session", and it 
is in an INVITE, UPDATE, PRACK, or responses to those, then
it is the 
description of the session for this invite, subject to the
offer/answer 
rules.

Note that the *default* content-disposition for a body of
type 
application/sdp is "session" if it is found in one
of the above 
contexts. Otherwise the normal default disposition of
"render" applies.

So an application/sdp body without a content-disposition in
a MESSAGE 
should be rendered. Of course there are issues of how or if
it can be 
rendered, but that is what it should mean.

If you put an application/sdp body in a MESSAGE and
explicitly specified 
a disposition of "session" then of course it
shouldn't be rendered. 
There is no defined meaning for a body with disposition of
session in a 
MESSAGE, so presumably it should be considered an error or
ignored.

	Paul


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