Subject: [Simple] asking for a specific view

From: Jonathan Rosenberg <[email-masked]>
Date: Sun, 13 Jul 2003 08:04:22 -0400

Folks,

One of the conclusions of the tuple design team was that we want to 
allow a PA the flexibility to have tuples represent anything they 
want. This means that a PA can compose, aggregate, and otherwise 
discard information as it sees fit.

However, in some cases, a watcher is interested in a specific type of 
information, and furthermore, a specific type of information within 
the context of a specific view. As an example, a watcher application 
that wants to send an SMS to a phone when it finds its not in a call, 
will want to see a device-centric view of a user, so that it can check 
the call state of the device.

It is possible that, by default, the PA would not provide information 
to the watcher in a device-centric view. Rather, its policy is to send 
a single tuple with summary information. If this happens, the watcher 
doesnt get the information they need, since its been aggregated away. 
To remedy this, I think we need to enhance the filter work to allow a 
watcher to ask for a specific view of the presence data. We have some 
work to do to define a view, but we have a couple of good candidates 
to work from.

Thanks,
Jonathan R.
-- 
Jonathan D. Rosenberg, Ph.D.                600 Lanidex Plaza
Chief Technology Officer                    Parsippany, NJ 07054-2711
dynamicsoft
[email-masked]                     FAX:   (973) 952-5050
http://www.jdrosen.net                      PHONE: (973) 952-5000
http://www.dynamicsoft.com

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From: Henning Schulzrinne <[email-masked]>
Date: Sun, 13 Jul 2003 11:19:39 -0400

Jonathan Rosenberg wrote:

> It is possible that, by default, the PA would not provide information to 
> the watcher in a device-centric view. Rather, its policy is to send a 
> single tuple with summary information. If this happens, the watcher 
> doesnt get the information they need, since its been aggregated away. To 
> remedy this, I think we need to enhance the filter work to allow a 
> work to do to define a view, but we have a couple of good candidates to 
> work from.

Would this be as simple as being able to request certain columns (in my 
database view of the world)?

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From: Henning Schulzrinne <[email-masked]>
Date: Sun, 13 Jul 2003 11:19:39 -0400

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From: Jonathan Rosenberg <[email-masked]>
Date: Mon, 14 Jul 2003 20:23:36 -0400

> database view of the world)?

No. Its closer to what you were calling the pivot operation. But more 
importantly, it means that the attributes have values (and indeed 
exist) which are relevant for that particular view. For example, in a 
"device centric" view, things like whether the device is on or off, 
the placetype, geoloc, etc., make sense and have a well defined 
meaning. For other views, such as Brian's one-tuple view, there could 
also be a placetype and geoloc, but they might represent where the 
user is (based, perhaps, on a device which is almost always on the 
body of the person in question), as opposed to one of his devices.

Adam writes:
> I'm pretty certain that you're going to run into a lot of
> situations in which presence cannot be broken down along
> specific lines (like device or service views). For example,
> presence information may arrive at a PA already partially (or even
> fully) composed of information about multiple devices. You'll
> also often run into situations in which composition is performed
> as a means of intentional obscurity.

Sure. You can't always deliver what the watcher wants. But at least we 
should be able to know what they want, and deliver it if possible, or 
we are permitted to.

> 
> I'm not saying that your suggestion is bad, but I suspect
> that we'll discover that the cases in which requests
> for certain types of views make sense will be the exception
> rather than the norm. 

Well, that remains to be seen. We don't have a lot of deployment 
experience to see how these things will get used.

-Jonathan R.

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From: Jonathan Rosenberg <[email-masked]>
Date: Mon, 14 Jul 2003 20:23:36 -0400

-Jonathan R.

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From: Ben Campbell <[email-masked]>
Date: 15 Jul 2003 03:41:41 -0500

> should be able to know what they want, and deliver it if possible, or 

I would state this more strongly, in that the PA has complete control
over what it delivers. Such a request is at best a hint of watcher
preference. But in general, the PA is an agent of the presentity, and is
not obligated to care about the preferences of a watcher. Anything
beyond that is in conflict with one of the most useful attributes of
SIP, that is, the owner of a resource has controls how and where calls
are delivered.

Or in more practical terms, a watcher implementation MUST NOT assume its
preferences will be honored.

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From: Ben Campbell <[email-masked]>
Date: 15 Jul 2003 03:41:41 -0500