Subject: Re: [Sipping] Re: draft-holmberg-sipping-199-00.txt

From: [email-masked]
Date: Mon, 9 Apr 2007 16:49:16 -0400

From: "Christer Holmberg \(JO/LMF\)" <[email-masked]>

   Because, in some cases 199 may be useful to peopleeven if they don't
   know whe IP source information etc for a stream associated with the
   early dialog. "Resource" may have different meaning for different
   applications, access types and network architectures.

Well, off the top of my head, I don't see any real usefulness of 199
unless the UAC can use it to terminate consideration of a media
stream.  So to make it worth moving forward, we either need to find
another reason that it's useful, or work out the media stream
correlation.

Dale

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From: "Christer Holmberg \(JO/LMF\)" <[email-masked]>
Date: Tue, 10 Apr 2007 09:51:43 +0200

Hi,

>>Because, in some cases 199 may be useful to peopleeven if 
>>they don't know whe IP source information etc for a stream associated
with the
> 
>Well, off the top of my head, I don't see any real usefulness 
>of 199 unless the UAC can use it to terminate consideration 
>of a media stream.  So to make it worth moving forward, we 
>either need to find another reason that it's useful, or work 
>out the media stream correlation.

You may be able to free stream related resources even if you are not
able to associate the stream with the dialog. For example, if you have
reserved codec X only for the stream that is terminated, you know that
you can free the resources associated with that codec.

Another use-case is pre-conditions. When the dialog is terminated, you
can terminate any procedures related to pre-conditions for that dialog.

Another use-case is in-band security negotiation, which you can
terminate when the dialog is terminated. Yes, in this case you need to
be able to associate the dialog with the media.

Another use-case is where the P-Early-Media header is used. A UA may
trigger different actions depending on whether the header has been used
for a specific dialog.

During the early media discussions in Prague it was indicated that we
need to start working on a mechanism to associate dialogs with media,
and I strongly support that initiative. But, again, I would like to
handle it as a separate item, because it's not only related to 199.

Regards,

Christer

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From: [email-masked]
Date: Tue, 10 Apr 2007 17:03:31 -0400

For example, if you have reserved codec X only for the stream that
   is terminated, you know that you can free the resources associated
   with that codec. [2 further examples delete]

OK, you've convinced me.

Dale