[GeoJSON] Aligning implementations
Chris Holmes
cholmes at openplans.org
Mon Apr 9 18:55:04 PDT 2007
Tim Schaub wrote:
> Chris Holmes wrote:
>> I definitely have a set of users who want to be able to serve up data
>> even if it doesn't have a geometry.
>
> Ok, I still like
>
> geometry: {
> type: null,
> data: []
> }
>
> better than
>
> geometry: null
>
> or no sign of geometry at all.
>
>> [multiple geometries]
>> what do I do?
>
> Not that hard to say that the data structure should be (for each feature):
>
> {
> id: string,
> geometry: array,
> properties: object
> }
>
> Though I wonder if people would complain about having to do geometry[0]
> (or equivalent) most of the time.
Yeah, I don't really like that so much. If you have multiple geometries
people will probably want names for them. Ie which one's the building
and which one's the lot. If you just have an array you don't know which
is which.
I'm more inclined to just allow geometry objects to also be embedded as
one or more of the properties.
>
> You got me curious about all these people who want to serve up
> geographic features with no geometry. I wonder if you just mean null or
> broken geometry - or if there really is a world where people deal in
> geography without geometry.
I mostly mean null or broken geometries. But I've also got people who
are using a WFS to expose their data. They may have a bunch of tables,
say a bunch of samples of rocks and the time they were taken, that are
linked to a specific location. They do a join on the data and present
the result, each location has zero or more data samples. Now presenting
this obviously has a location, and can go through WMS and WFS.
So they've already exposed their data. But if they want to just expose
their data samples table, then it's easy as pie if they've already got a
WFS configured for their other data. They just turn it on, and it's
able to spit out XML, and if we do this, then JSON as well, through the
WFS protocol. And indeed eventually I may even try for a more RESTful
feature service that exposes GeoJSON. If organizations have it set up
for their geospatial data, then they can easily turn it on for other
data. I think it's great if WMS/WFS is the way in to organizations
exposing their data to the web. And yes, I realize that it then won't
be GeoJSON, and then we just wouldn't include a geometry. But if you
have an application that doesn't necessarily use the geospatial part of
the geojson data it's working against then it could benefit from this.
Chris
>
> Tim
>
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--
Chris Holmes
The Open Planning Project
http://topp.openplans.org
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