On Wed, 2003-07-16 at 11:38, Paul Kyzivat wrote:
> 
> > +------------+          +--------------+          +-------------+
> > |            |          |  proxy/      |          |             |
> > |  UA1       |          |  registrar   |          |  UA2        |
> > +-----+------+          +-------+------+          +------+------+
> >       |                         |                        |       
> >       |     SUBSCRIBE           |                        |       
> >       +------------------------->                        |       
> >       |     OK                  |                        |       
> >       <-------------------------+                        |       
> >       |     NOTIFY              |                        |       
> >       <-------------------------+                        |       
> >       |     OK                  |                        |       
> >       +------------------------->                        |       
> >       |                         |     REGISTER           |       
> >       |                         <------------------------+       
> >       |                         |     OK                 |       
> >       |                         +------------------------>       
> >       |     NOTIFY              |                        |       
> >       <-------------------------+                        |       
> >       |     OK                  |                        |       
> >       +------------------------->                        |       
> 
> This could be considered valid, but IMHO isn't a mainstream approach.
> 
> The proxy/registrar/pa isn't technically doing anything wrong. But 
> presumably it is getting all of its information from the register 
> message. This may be sufficient for open/closed, but its not clear how 
> it would get any more presence information.

Yes, I've often wondered about this as well. Considering the NOTIFY
bodies are extensible (at least with cpim-pidf+xml format) it's
difficult to see how the registrar could derive this. This sort of
argues for the second approach.

> You could couple this with UA2 sending PUBLISH messages to its own AOR, 
> which would be handled by the PA function of the server. Then it would 
> make more sense.

I'm not familiar with the PUBLISH request, I will look into it..

> > +-----------+        +--------------+         +--------------+ 
> > |           |        |  proxy/      |         |              | 
> > |   UA1     |        |  registrar   |         |    UA2       | 
> > +-----+-----+        +-------+------+         +-------+------+ 
> >       |   SUBSCRIBE          |                        |        
> >       +---------------------->                        |        
> >       |   PENDING            |                        |        
> >       <----------------------|     SUBSCRIBE          |        
> >       |                      ------------------------->        
> >       |                      |     OK                 |        
> >       |   OK                 <------------------------+        
> >       <----------------------|                        |        
> >       |                      |                        |        
> >       |                      |                        |        
> >       |                   NOTIFY                      |        
> >       <-----------------------------------------------+        
> >       |                     OK                        |        
> >       +----------------------------------------------->        
> >       |                      |                        |        
> 
> I'm not sure about this because I don't know what you intend by the line 
> marked PENDING. If you mean this to be a 100 response, then this could 
> be ok.

Yes, actually it's a 100-level response. I probably shouldn't have used
the "PENDING" word..

> > +------------+       +--------------+      +---------------+
> > |            |       |  proxy/      |      |               |
> > |   UA1      |       |  registrar   |      |     UA2       |
> > +-----+------+       +-------+------+      +-------+-------+
> >       |    SUBSCRIBE         |                     |        
> >       +---------------------->                     |        
> >       |    PENDING           |                     |        
> >       <----------------------+      SUBSCRIBE      |        
> >       |                      ---------------------->        
> >       |                      |      OK             |        
> >       |    OK                <---------------------+        
> >       <----------------------+                     |        
> >       |    NOTIFY            |                     |        
> >       <----------------------+                     |        
> >       |    OK                |                     |        
> >       +---------------------->                     |        
> >       |                   NOTIFY                   |        
> >       <--------------------------------------------+        
> >       |                     OK                     |        
> >       +-------------------------------------------->        
> >       |                      |                     |        
> >       |                      |                     |        
> 
> This isn't a good situation. The presence event package says that 
> subscriptions aren't supposed to be forked. UA1 doesn't know what to do 
> with notifications from different sources.

I tend to agree ... I think what's happening in my case is that I have a
registrar/proxy configured to act as in example #1, but it's also doing
something strange by proxying the original subscribe request.

Thanks for the input ...
-- 
David Stuart, SIPQuest
phone: 254-8886 x234 web: http://www.sipquest.com/

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