Subject: [Geopriv] GeoPriv geodetic example

From: "James Winterbottom" <[email-masked]>
Date: Thu, 2 Dec 2004 09:13:07 +1100

Hi All,

The geodetic example in draft-ietf-gepriv-pidf-lo-03 shows the usage of the
gml:location type based around the gml:point and gml:coordinates elements.
This is just a heads up that in gml version 3.1, the gml:location and
gml:coordinates types have been deprecated. For those that attended the
ECRIT BoF you may remember a discussion from Henning about problems with the
convention of encoding latitude and longitude into the coordinates type,
things surrounding number of spaces, colons etc. Both of these potential
problems would go away if instead of using  gml:location and
gml:coordinates, we used gml:position and gml:pos. Both position and pos are
available in GML3.0 feature.xsd.

I know that this is only an example and that the draft does not say that you
MUST use location and coordinates, but I think that a position and pos
example might be a better example moving forward.

In GML 3.1, position and pos are recommended as the preferred means for
specifying a point. They avoid the format issues of coordinates by extending
a doublelist, so latitude and longitude are both specified as degrees and
decimal degrees, with a single space between elements in the list. The
example as provided in the current GeoPriv draft would change as follows if
using position and pos in place of location and coordinates.

<?xml version="1.0" encoding="UTF-8"?>
    <presence xmlns="urn:ietf:params:xml:ns:pidf"
       xmlns:gp="urn:ietf:params:xml:ns:pidf:geopriv10"
       xmlns:gml="http://www.opengis.net/gml"
       entity="pres:[email-masked]">
     <tuple id="sg89ae">
      <status>
       <gp:geopriv>
         <gp:location-info>
           <gml:position>
             <gml:Point gml:id="point1"
srsName="urn:EPSG:geographicCRS:4326">
               <gml:pos>37.775 -122.4194</gml:pos>
             </gml:Point>
            </gml:location>
         </gp:location-info>
         <gp:usage-rules>
           <gp:retransmission-allowed>no</gp:retransmission-allowed>
           <gp:retention-expiry>2003-06-23T04:57:29Z</gp:retention-expiry>
         </gp:usage-rules>
       </gp:geopriv>
      </status>
      <timestamp>2003-06-22T20:57:29Z</timestamp>
     </tuple>
    </presence>

Cheers
James

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---

From: Tschofenig Hannes <[email-masked]>
Date: Thu, 2 Dec 2004 16:25:16 +0100

hi james, 
 
that's very good feedback. i have also noticed that there is a gml 3.1
version available and i was aware of the different options gml offers. it is
certainly helpful to read the document and to see whether some features have
been deprecated. we might want restrict the functionality a bit further to
make it easier for implementors. during the geopriv meeting we discussed
this issue and there was an agreement that we can only make minor
modifications to pdif-lo but we might want to work on a document which
captures implementation experience with pidf-lo. 
 
ciao
hannes

  _____  

From: James Winterbottom [mailto:[email-masked]] 
Sent: Mittwoch, 01. Dezember 2004 23:13
To: Tschofenig Hannes; [email-masked]
Subject: GeoPriv geodetic example

Hi All, 

       xmlns:gml="http://www.opengis.net/gml <http://www.opengis.net/gml> " 

Cheers 
James