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

From: "Li Hua Tang" <[email-masked]>
Date: Tue, 5 Mar 2002 15:49:54 +0800

Jonathan Rosenberg wrote:
>It recommends that the
>watcherinfo subscription be sent on the same dialog as the presence
>subscription. THis guarantees that the same server handling presence, is
>also handling watcherinfo.
Why the same dialog? It's possible that no presence subscription hasn't
been sent before a winfo subscription. And a SUBSCRIBE request for winfo
will definitely create a new dialog since it has a new callID.

>> More, if the PS can't terminate this subscription, are they the
>> set of watchers who return their watcher information to B independently?
>> It's difficult to understand this way.

>There are two solutions for this case. Both are docuented in -01. In the
>first case, the PS will fork the watcherinfo subscription, and the
>result is that multiple subscriptions are installed. In the second case,
>the PS can direct the watcherinfo subscription to a server that the
>network has explicitly designated as the winfo server, and it knows
>about all watchers.

I'm much confused. What you have said seems selfcontradicting. Since PS
will handle the presence subscription, in your opinion, the PS should be
the same server to handle the winfo subscription. Return to my original
question. If the PS uses PA/Proxy/Registrar model, it can't act as the
winfo server at the same time. Due to the recursion, it's reasonable to
colocate presence sever and winfo server. But if the SUBSCRIBE request is
proxying, the server will lose control of presence status.

One more point I am not very clear about winfo-package-01. Should a
notification of winfo subscription return immediately?

Best regards,
Tang Lihua
Email:  [email-masked]

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---

From: Jonathan Rosenberg <[email-masked]>
Date: Tue, 05 Mar 2002 03:12:07 -0500

Li Hua Tang wrote:
> Why the same dialog? 

So that it gets to the same server handling the presence subscription.

> 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
track 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

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

> the same server to handle the winfo subscription. 

Whatever handles the presence subscription, handles the watcherinfo
subscriptions.

> Return to my original
> winfo server at the same time.

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.

> Due to the recursion, it's reasonable to

Whatever handles the presence subscription, handles the watcherinfo
subscriptions.

> notification of winfo subscription return immediately?

What does "return immediately" mean? It generates an immediate NOTIFY,
if that is what you mean. That is true for all sip event packages.

-Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.            72 Eagle Rock Avenue
Chief Scientist                         First Floor
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