Subject: Re: [Simple] watcher info problem in PA/Proxy/Registrar model

From: "Li Hua Tang" <[email-masked]>
Date: Tue, 5 Mar 2002 17:02:52 +0800

Jonathan Rosenberg wrote:

> > It's possible that no presence subscription hasn't
> > been sent before a winfo subscription.

> That is not the case we are discussing. IN this case, a user wants to
> rack the status of his own subscription to some other resource. By
> definition, this is a watcherinfo subscription associated with some
> other existing subscription.

> > And a SUBSCRIBE request for winfo
> > will definitely create a new dialog since it has a new callID.

> Not in this case. The meaning of sending the subscription on the same
> dialog is to reuse the call-id, to, from.

I can't agree with you. In order to do realtime authorization (or say, in
oder to be notified as soon as being subscribed), the presentity can send
winfo subscription to the PS first even if there is no presence
subscription to it. It's independent on whether a watcher has subscribed or
will subscribe to the resource of this presentity. It's not associated with
an exsiting subscription.

And it can be guaranteed that all the winfo subscriptions to one resource
have the same callid since they may be generated by any watcher or the
presentity itself.

> Now to me, you are saying contradicting things. Either the PS is a PA,
> or it is a proxy. If its a PA, it terminates the watcherinfo
> subscriptions. If its a proxy, it proxies the watcherinfo subscriptions.

Either the PS is a PA, or it is a proxy. Do you mean the PS can't be a
combination of PA/Proxy/Registrar? Or do you mean the PS can't change the
role between PA and Proxy when handling subscriptions whenever the
presentity changes status (available or not)?

Best regards,

Tang Lihua
Email:  [email-masked]

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---

From: Jonathan Rosenberg <[email-masked]>
Date: Thu, 07 Mar 2002 15:54:56 -0500

> an exsiting subscription.

That is correct, but that is not the case I am talking about here. I
think we are talking past each other.

There are TWO separate uses of a watcher info subscription. One, is a
subscription by the watcher themself, and the other, is from the
presentity. Pictorially:

     Please view in a fixed-width font such as Courier.

           (1) sub winfo            (2) sub winfo
       +-------------------+    +---------------------+
       |                   |    |                     |
       |                   V    V                     |
  +--------+             +--------+              +----+---+
  |presence|             |        |              |        |
  | watcher|------------>|  PA    |<------------ |presentity
  |        | sub presence|        |  publish pres|        |
  |        |             |        |              |        |
  +--------+             +--------+              +--------+

Case (1) is the presence subscriber being the watcherinfo subscriber.
Case (2) is the presentity being the watcherinfo subscriber.

In case (1), the winfo subscription, by definition, follows a presence
subscription. It can therefore go on the same dialog. In case (2), the
winfo subscription happens independently, and needs to go to all PA
which are publishing presence for that presentity.

> presentity changes status (available or not)?

No. I am saying that if a PS is a proxy for a presence subscription, it
has to be a proxy for a watcherinfo subscription for the same user. If a
PS is a PA for a presence subscription, it has to be a PA for a
watcherinfo subscription for the same user.

-Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.            72 Eagle Rock Avenue
Chief Scientist                         First Floor
dynamicsoft                             East Hanover, NJ 07936
[email-masked]                 FAX: (973) 952-5050
http://www.jdrosen.net                  PH:  (973) 952-5000
http://www.dynamicsoft.com
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