[Openstreetmap-dev] More on GPX schema

Immanuel Scholz immanuel.scholz at gmx.de
Wed Sep 21 19:24:43 BST 2005


Hi,

> The GPX schema also includes a <desc> (user description) tag. If we're using 
> Steve's suggestion for representing keys and values as a semicolon separated 
> list, they could go in the <desc> tag. The name should perhaps be separate 
> from the key/value list, as a name is a pretty fundamental feature of every 
> road.

Sorry, but I disagree. A list of values represented as xml-string is NOT
a description. <desc> is a description!

What I mean is: Please don't encode data within xml in an other,
proprietary data format.


> <trk>
> <number>50521</number>
> <name>Lodge Road</name>
> <desc>foot=yes; horse=yes; car=yes; class=secondary</desc>
> <trkseg>

To me, it should be look like (the tagname "osm" is negotiable ;)

<trk>
<number>50521</number>
<name>Lodge Road</name>
<extensions>
<osm name="foot" value="yes" />
<osm name="horse" value="yes" />
<osm name="car" value="yes" />
<osm name="class" value="secondary" />
</extensions>
<trkseg>
...


Of course, your way is shorter and less to transfer. But so is this:

<trk><name>50521|Lodge Road|foot=1;horse=1;car=1;class=secondary
</name></trk>


Perfectly legal gpx-structur. But not xml anymore. "Putting key/value
pairs, equal-seperated, in a list, comma seperated" is not xml anymore
either.


By the way: Personally I am not very attached to gpx (or even xml)
anyway. If the database scheme of OSM does not fit into gpx, as example
because it stores street segments as pairs only and the algorithm to
find pair chains from an unordered list is within O(n^2), you could
choose a more appropriate data representation than gpx. But if you
choose gpx, stick to it. That's my 2 cent ;-)

Ciao, Imi.







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