[OSM-dev] Using relations to save data

Andreas Kalsch andreaskalsch at gmx.de
Tue May 4 21:12:02 BST 2010

I am still reading some old mailing list posts ...

What about a relation with type="data", which is a relation that can 
include tags and other relations recusively?

This relation has no geometric reference but it is just there to save 
data. So we could reuse relations for a purpose which is not the main 
OSM one - instead of expensively defining a new data type. This type 
could be used to save tag definitions ( 
http://wiki.openstreetmap.org/wiki/Machine-readable_Map_Feature_list ) 
regularly in the database to be able to access the data with the API 
easily, which already provides versioning and changesets:

<relation id="...">
   <tag k="type" v="data" />
   <tag k="class" v="tag-def" />
   <tag k="key" v="name" />
   <tag k="onway" v="true" />
   <tag k="description:de" v="..." />
   <tag k="display-name:de" v="..." />
   <member type="relation" id="..." role="implies" />

Having a client-side framework with UI to access and change the data 
according to the model - a pendant to JOSM - makes sense.

I want to add this idea to proposed uses of relations in the wiki.


Am 19.02.09 23:35, schrieb Frederik Ramm:
> Hi,
> Steve Hill wrote:
>> I've been thinking about ways to improve the way objects are tagged in OSM
>> - for a long time I've seen some problems with the way we currently tag
>> things, and I finally got around to writing down some of my thoughts on
>> the subject.
> I *had* been wondering; we had the usual recurring left-right tagging
> discussion but the bi-monthly Absolutely New And Improved Tagging Scheme
> was overdue for a while. Thanks for jumping in and helping us out ;-)
> Your concept is utterly unworkable of course with the current software
> landscape, but if we leave that aside for a moment, then you do have an
> interesting point, in fact one that was raised by Jochen and myself in
> our April 2007 data model paper[1], back when we were still young and
> believed we could change the world.
> Quoting from that paper:
> "Instead of having a geometric object with some properties, we instead
> think of objects with some properties (like “this is a museum” and “this
> has the name Natural History Museum”) and the added property of “this
> object is positioned at such and such a location”. ... So the geometry
> is not the object itself, as it is now, but it is just one property of
> some kind of abstract object."
> I believe this is indeed the way many pros are doing it - there is an
> object and the geometry is one of many properties of the object. It is a
> concept to keep in mind for the more distant future; I don't think we
> should aim to do it with the current implementation of relations though.
> Bye
> Frederik
> [1]http://www.remote.org/frederik/tmp/towards-a-new-data-model-for-osm.pdf

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