RE: [Geopriv] coming to terms on location by reference

You don't need much of a stack. The smallest embedded stack could be wacked
in half and work (if it supported SUBSCRIBE/NOTIFY in the first place).
I think the PC could use the identity it already has from the DSL network
(it has a userid, which it combines with the domain name, as it would for
email). The PC would take the hostname of the LbyR URL and look for a SIP
SRV record in the DNS, and send the SUBSCRIBE there.

The while transaction looks like:
    SUBSCRIBE sip:resource@example.com SIP/2.0
      Via: SIP/2.0/TCP watcherhost.example.com;branch=z9hG4bKnashds7
      To: <sip:resource@example.com>
      From: <sip:user@example.com>;tag=xfg9
      Call-ID: 2010@watcherhost.example.com
      CSeq: 17766 SUBSCRIBE
      Max-Forwards: 70
      Event: presence
      Accept: application/pidf+xml
      Contact: <sip:user@watcherhost.example.com>
      Expires: 600
      Content-Length: 0

   F2 200 OK example.com server->watcher

      SIP/2.0 200 OK
      Via: SIP/2.0/TCP watcherhost.example.com;branch=z9hG4bKnashds7
        ;received=192.0.2.1
      To: <sip:resource@example.com>;tag=ffd2
      From: <sip:user@example.com>;tag=xfg9
      Call-ID: 2010@watcherhost.example.com
      CSeq: 17766 SUBSCRIBE
      Expires: 600
      Contact: sip:server.example.com
      Content-Length: 0

   F3 NOTIFY example.com server-> watcher

      NOTIFY sip:user@watcherhost.example.com SIP/2.0
      Via: SIP/2.0/TCP server.example.com;branch=z9hG4bKna998sk
      From: <sip:resource@example.com>;tag=ffd2
      To: <sip:user@example.com>;tag=xfg9
      Call-ID: 2010@watcherhost.example.com
      Event: presence
      Subscription-State: active;expires=599
      Max-Forwards: 70
      CSeq: 8775 NOTIFY
      Contact: sip:server.example.com
      Content-Type: application/pidf+xml
      Content-Length: ...

      [PIDF Document]

   F4 200 OK watcher-> example.com server

      SIP/2.0 200 OK
      Via: SIP/2.0/TCP server.example.com;branch=z9hG4bKna998sk
        ;received=192.0.2.2
      From: <sip:resource@example.com>;tag=ffd2
      To: <sip:user@example.com>;tag=xfg9
      Call-ID: 2010@watcherhost.example.com
      CSeq: 8775 NOTIFY
      Content-Length: 0

Rosenb

I presume the PC would use the identity it already has for a typical DSL
provider.

> -----Original Message-----
> From: Stark, Barbara [mailto:Barbara.Stark@BellSouth.com]
> Sent: Wednesday, September 13, 2006 4:08 PM
> To: Brian Rosen; Dawson, Martin; Andrew Newton; geopriv@ietf.org
> Subject: RE: [Geopriv] coming to terms on location by reference
>
> > Clients need only implement SIP Subscribe/Notify to be compatible with
> any
> > LIS.
>
> Brian,
> I'm not very up-to-speed on this SIP SUBSCRIBE/NOTIFY stuff, and was
> hoping you could help explain something. I'm trying to understand what
> would be needed on a device that either doesn't have a fully functional
> SIP client (that may or may not be configured to make calls), or that
> doesn't know it has such a client.
>
> For example, I think I'd like for a PC to do location determination
> shortly after starting. Always. My PC may or may not have a SIP client
> application on it. Right now, I don't subscribe to any VoIP service, so
> I don't have a client on it. And let's say that the PC is given a
> location reference, and wants to go ahead and de-reference, so it has
> what it needs for a LoST look-up.
>
> How much of a SIP stack do I need for a SUBSCRIBE/NOTIFY? Is there a
> suggestion as to how the PC identifies itself in the SIP message (I'm
> assuming the PC doesn't have an account with a voice service provider,
> or such, since that wouldn't be good to require of it)? I'm not too
> clear on how point-to-point SIP works, but where does the PC go to look
> up the SIP urn that it sends the SUBSCRIBE to, so it has an IP address
> for routing? Does this need to be hard-coded into the operating system?
> Or is any look-up required?
>
> I really am curious, really don't know, and I'm not just pretending to
> be dumb...
> Barbara
>
> *****
>
> The information transmitted is intended only for the person or entity to
> which it is addressed and may contain confidential, proprietary, and/or
> privileged material. Any review, retransmission, dissemination or other
> use of, or taking of any action in reliance upon this information by
> persons or entities other than the intended recipient is prohibited. If
> you received this in error, please contact the sender and delete the
> material from all computers. GA624

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Received on Wed, 13 Sep 2006 16:33:58 -0400