Re: [Sip] Additional uses of INFO

Dale.Worley@comcast.net wrote:

>    Content-type tells about what the content is. Content-disposition  
>    tells about what one is supposed to do with the content, and might be  
>    a better candidate for this sort of usage. Or perhaps a combination  
>    of the two.
> 
>    If I send you an image/jpeg during a call, what do you do with it?  
>    Display it? Add it to your phone book next to my name? Run a  
>    steganographic search on it to look for a hidden message?
> 
> Ah, yes.  But I note that you can define x-* Content-Dispositions as
> well.  (RFC 2045 via RFC 2183 via RFC 3261!)
> 
> For that matter, we should start getting people used to defining
> Content-Dispositions to describe the roles of message bodies.  Might I
> suggest draft-ietf-sip-hop-limit-diagnostics-03, "Diagnostic Responses
> for Session Initiation Protocol Hop Limit Errors", as a good place to
> start?  It proposes a message/sipfrag body to the 483 response that
> gives the contents of the failed request.  There ought to be a
> Content-Disposition to explain the significance of that body.

I agree there is a lot of potential in Content-Disposition. But it 
suffers from a lack  of clear specification about how it is to be used.

I have a strong suspicion that most UAs totally ignore Content-Disposition.

Question: If you send an INVITE containing an SDP body with 
Content-Disposition:render, how many will think it is an offer?

It would be a good thing to start using this for more in order to 
motivate support. But it will take awhile before it starts working 
widely. Starting by using it in something like INFO (rathere than 
INVITE) is probably a good baby step in that direction.

	Paul

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