Subject: Re: [sipcore] Content-Disposition questions
From: "Stach, Thomas" <[email-masked]>
To: Christer Holmberg <[email-masked]>, "[email-masked]" <[email-masked]>
Date: Tue, 10 Mar 2015 09:45:50 +0000
List-Id: SIP Core Working Group <sipcore.ietf.org>

Christer,

> 
> Hi Thomas,
> 
> My issue is not so much related to specific usages of the handling parameter -
Understood. 
More inline

> but what the default value is when not present in the message.
> 
> Regards,
> 
> Christer
> 
> -----Original Message-----
> From: Stach, Thomas [mailto:[email-masked]]
> Sent: 09 March 2015 17:54
> To: Christer Holmberg; [email-masked]
> Subject: RE: Content-Disposition questions
> 
> Christer,
> 
> I don't know if that helps with your question, but if you tunnel QSIG over SIP
> it would most likely done using ECMA-355 or the ISO's equivalent IS 22535
> 
> Here, the handling parameter would be set to "required".
> 
> - http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-355.pdf
> -
> http://standards.iso.org/ittf/PubliclyAvailableStandards/c052060_ISO_IEC_22535
> _2009(E).zip
> 
> 
> Regards
> Thomas
> 
> From: sipcore [mailto:[email-masked]] On Behalf Of Christer Holmberg
> Sent: Montag, 9. März 2015 13:26
> To: [email-masked]
> Subject: [sipcore] Content-Disposition questions
> 
> Hi,
> 
> Section 20.11 of RFC 3261 says:
> 
>         "For backward-compatibility, if the Content-Disposition header field
>         is missing, the server SHOULD assume bodies of Content-Type
>         application/sdp are the disposition "session", while other content
>         types are "render"."
> 
> Section 20.11 also says:
> 
>         "The handling parameter, handling-param, describes how the UAS should
>         react if it receives a message body whose content type or disposition
>         type it does not understand. The parameter has defined values of
>         "optional" and "required". If the handling parameter is missing, the
>         value "required" SHOULD be assumed. The handling parameter is
>         described in RFC 3204 [19].
> 
> 
> QUESTION_1: If the C-D header field is missing, and the default disposition
> type value ("render") is assumed, shall then the default handling value
> ("required") also be assumed?

Yes, for unknown message bodies with the following exception.
Since RFC3204 is a normative reference, "qsig" and "isup" are not "unknown" and 
treated as specified there, 
i.e. Content-Disposition: signal; handling=optional

> 
> 
> 
> RFC 3204, which RFC 3261 refers to, says that the default disposition type
> value for ISUP and QSIG bodies are "signal".
> 
> QUESTION_2: If, for a specific message body, the "render" default type can be
> overwritten, shouldn't that be mentioned in 3261?

I think this is already written down. The last sentence in section 20.11 reads
"   If this header field is missing, the MIME type determines the default
   content disposition.  If there is none, "render" is assumed."

So, if the MIME type is understood, the default disposition from the 
corresponding MIME definition applies. Of course, this default disposition 
can be overwritten by sending a corresponding C-D header field, as e.g. ECMA-355 does for "qsig".
"render" kicks in, only if the MIME type is not understood and if C-D is omitted.
Does this make sense?

Regards
Thomas

> 
> 
> Regards,
> 
> Christer