Got it in 1!  Tagging the message with the context, also known as event in
3265 parlance, fixes the INFO application routing / context problem.  I was
one of the first to say we could fix INFO.  In fact, I started revising
Dean's draft of almost 5 years ago before I realized I was totally
recreating SUBSCRIBE/NOTIFY.

In particular, the requesting party MUST do something that looks like a
SUBSCRIBE, outside of the INVITE?  Why?  Because the call will fail if the
particular reporting, like DTMF, is no supported.  If the argument is
reporting DTMF is a rare occurrence for, e.g., H.323 gateways, then failing
a call to the H.323 gateway from a SIP Phone is not a desirable feature.

The reason I decided not to go on that route is at best you save 2 messages
(the instant NOTIFY and 200 OK) over using 3265.  At that point, might as
well use 3265.


That said, I suppose, we could offer a "fast start" 3265.  [If this has
shades of H.323...]  In this scenario the fact you advertise support or
acceptance of particular INFO-packages is enough to enable a sender to send
appropriately tagged INFO's to you.

Of course, if one of those INFO's fails, then I will bet 75% of the
implementations will tear down the call.  25% will leave the call up and RTP
port open forever.

I would also offer we give this mechanism a new method name, as it will NOT
be backwards-compatible with INFO.


On 10/15/07 11:26 AM, "Brian Stucker" <[EMAIL PROTECTED]> wrote:

> 
> 
>> -----Original Message-----
>> From: Dean Willis [mailto:[EMAIL PROTECTED]
>> On Oct 11, 2007, at 4:34 PM, Eric Burger wrote:
>> 
>>> Right: "DTMF may not be the only information users want to send to
>>> each other during a session."  This is why one MUST
>> establish multiple
>>> subscription dialogs.  How else would one keep track of the
>> different
>>> elements / local routing decisions?  If you are proposing
>> application
>>> routing a'la P-Asserted-Service...
>>> 
>> 
>> One of the arguments for INFO is that it happens in a dialog,
>> not a session. That is, even if you have multiple event
>> streams, they happen on the same dialog.
>> 
>> The trick is demuxing the event streams, or in other words,
>> figuring out the context for each event. INFO currently gives
>> us nothing but the content- modifiers to figure this out.
>> That's not enough, as has widely been argued.
> 
> How does 3265 make this any better?
> 
> We're talking about identifying a data blob using an event plus a
> content-type instead of a supported plus a content-type for a period of
> time to start and end in conjunction with the INVITE dialog (so the
> subsciption-state header is mooted).
> 
> So a NOTIFY with an event header or an INFO without an event header, all
> other things being the same and the constrained semantics of the NOTIFY
> usage being put forward here...
> 
> Wouldn't it be equally valid to simply allow the INFO message to carry
> an event header and say that INFO is the same as a NOTIFY with an
> implicit subscription to an INVITE dialog? Isn't this pretty much what
> it does already (minus the event header).
> 
> Deep thought: Is all INFO is missing is simply the event header?
> 
> Regards,
> Brian
> 



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