Subject: [Simple] Accept header

From: Brazier Lachlan <[email-masked]>
Date: Fri, 25 Oct 2002 12:36:46 +0200

Hello,
sorry if this question was awnsered before. I have a question concerning the
Accept header.

RFC3261 states:

20.1 Accept

   The Accept header field follows the syntax defined in [H14.1].  The
   semantics are also identical, with the exception that if no Accept
   header field is present, the server SHOULD assume a default value of
   application/sdp.

   An empty Accept header field means that no formats are acceptable.

whereas RFC2616 (HTTP1.1) states in chapter "14.1 Accept"

....If no Accept header field is present, then it is assumed that the
   client accepts all media types. ......

Here I asume that RFC3261 counts concerning the Accept header. Is this
correct?
What's the difference between "no Accept header field" and "empty Accept
header field" ?

Which behaviour is defined in SIMPLE, as draft-ietf-simple-presence-07.txt
says, that

...All subscribers MUST support the "application/cpim-pidf+xml" presence
data format described in [5].....

Does this mean, that even when the Accept header field is empty, the
Subscriber MUST support the media type "application/cpim-pidf+xml"?
Actually I believe, a PA should send an error response containing an Accept
header field with "application/cpim-pidf+xml".
Is this correct?

Thanks
Lachlan Brazier

---

From: Jonathan Rosenberg <[email-masked]>
Date: Sun, 27 Oct 2002 22:11:54 -0500

Brazier Lachlan wrote:
> Hello,
> sorry if this question was awnsered before. I have a question concerning 
> the Accept header.
> 
> RFC3261 states:
> 
> 20.1 Accept
> 
> Here I asume that RFC3261 counts concerning the Accept header.

Yes.

  Is this
> What's the difference between "no Accept header field" and "empty Accept 

Empty means it looks  like:

SUBSCRIBE sip:[email-masked] SIP/2.0
Accept:
From: sip:[email-masked]
......

this means, "I don't support ANY document formats".

no accept field looks like:

SUBSCRIBE sip:[email-masked] SIP/2.0
From: sip:[email-masked]

which means, "The accept header has a default value".

> 
> Which behaviour is defined in SIMPLE, as 
> draft-ietf-simple-presence-07.txt says, that
> 

Now, this brings an interesting point. Since the default accept header 
field value is SDP, as bis says, it would seem that a subscriber has to 
include application/cpim-pidf+xml in an Accept header in every 
subscriber request. That needs to be corrected in the presence doc.

> Subscriber MUST support the media type "application/cpim-pidf+xml"?

An empty Accept header field in a SUBSCRIBE would be illegal, in 
violation of the presence spec, since it means you don't support pidf.

> 
> Actually I believe, a PA should send an error response containing an 
> Accept header field with "application/cpim-pidf+xml".

yup.

-Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.                72 Eagle Rock Ave.
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