Re: [Geopriv] Long review of draft-ietf-geopriv-loc-filters-07

["Hannes Tschofenig" <Hannes.Tschofenig at gmx.net>]

I agree with you that there are useful cases where one would want to state something like "please send me a notification when the target moves faster than XYZ kmph."

We would have to define a custom filter for doing that since just applying the filter RFC does not give us all we want. 

Ciao
Hannes

-------- Original-Nachricht --------
> Datum: Wed, 04 Nov 2009 01:01:20 -0600
> Von: "James M. Polk" <jmpolk at cisco.com>
> An: "Hannes Tschofenig" <Hannes.Tschofenig at gmx.net>, "\'Brian Rosen\'" <br at brianrosen.net>, geopriv at ietf.org
> Betreff: Re: [Geopriv] Long review of draft-ietf-geopriv-loc-filters-07

> Hannes
> 
> in-line below
> 
> At 06:29 PM 11/3/2009, Hannes Tschofenig wrote:
> >Hi James,
> >
> >Thanks for your detailed review. I am in the process of updating it and
> have
> >comments here and there.
> >
> >Here is one:
> >
> >Draft Text:
> >
> >--------
> >
> ><?xml version="1.0" encoding="UTF-8"?>
> ><filter-set xmlns="urn:ietf:params:xml:ns:simple-filter">
> >     <ns-bindings>
> >         <ns-binding prefix="dyn"
> >             urn="urn:ietf:params:xml:schema:pidf:dynamic"/>
> >     </ns-bindings>
> >     <filter id="123" uri="sip:presentity at example.com">
> >         <trigger>
> >             <changed by="3"> [<---James]
> >               //dyn:speed
> >             </changed>
> >         </trigger>
> >     </filter>
> ></filter-set>
> >
> >------
> >
> >[James]
> >
> >I get the XML,
> >but I don't see what the speed now is of
> >the device/target?
> >What if this device is moving at 200kmph,
> >where would that be placed in the XML?
> >Of, is this left for the application at the
> >subscriber to calculate?
> >If the latter is true, something needs to be
> >said about this expectation.
> >
> >------
> >
> >The filter would not tell you what the current speed is.
> 
> ok, I get that now (though it isn't exactly stated this way explicitly).
> 
> Let me pose a scenario for you and see if there is just one NOTIFY or 
> there are many:
> 
> Alice is the target.  Initially she isn't moving.  her device accepts 
> a subscription with a <changed by="3"> element in it.  She starts to 
> accelerate (linear or not) until se reaches 100mps.  How many NOTIFYs are
> sent?
> 
> 1 because she crossed the by="3" attribute, or each time she 
> accelerates more than 3mps faster since the last NOTIFY.
> 
> I'm guessing the latter, but want to be sure.
> 
> Again, this isn't exactly explicitly stated in the -07 rev.
> 
> James
> 
> BTW -- I think Alice sending a NOTIFY every time she accelerates or 
> decelerates by="3" would be useful information, especially in the 
> emergency case.
> 
> It's toobad we cannot have a "is moving" but less than by="3" 
> indication.  This would tell us it is in a stationary position or 
> not. Again, for a device/inventory tracking application, this would 
> seem like very useful information to have.
> 
> 
> >The current document only supports 'by' and hence you cannot say
> something
> >like 'tell me when he goes faster than 100kmph'.
> >
> >Ciao
> >Hannes
> >
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