Viewing realtime data in CKAN and styling geojson data

[Matthew Fullerton]

Short version:
@global: Are these things anything anyone would like to be able to use in their CKAN? I would have to do some more work to add a UI for configuration and so.
@dev: Are these things best put into new extensions with (inevitably) some duplication or as options in current extensions with (inevitably) some bloating of code over and above typically needed features?

@Steve: Would this be good material for (a) blog post(s)

Long version:

Dear CKAN community,
I have some experimental work that I would like to get some feedback on.

- Styling GeoJSON data
The GeoView extension makes it easy to add resource views of GeoJSON data. In our extended extension, attributes of the features (lines, points) in the FeatureCollection are styled according to MapBox's SimpleStyle spec[1]. Here's an example where the file has been processed to add colors based on traffic flow state:
https://smartlane.io/dataset/different-geo-visualizations/resource/49f0fcff-b3c8-48c8-b1c6-ddc33e4a83fe

And another where the points are styled to (vaguely) look like colored traffic lights:
https://smartlane.io/dataset/different-geo-visualizations/resource/a4e397ad-cbd9-48bf-a77a-296c5fcc9559
(watch out, it can take a while to load)

- Realtime GeoJSON data
Using leaflet.realtime[2], an extension for the leaflet library that CKAN (GeoView) uses to visualize GeoJSON, maps can have changing points or colors/styles. Here is an example of traffic lights changing according to pre-recorded data:
https://smartlane.io/dataset/traffic-light-stream-frankfurt-niederrad/resource/b6e4319e-f29b-480b-ad6d-214a753d3c2d

I'll try and add a demo with moving data points soon, it ought to work without any further code changes. The problem is often getting the live data in GeoJSON format... but we have a backend for preprocessing other data.

- Realtime data plotting
By making only a few small changes, we are able to continuously update Graph views. You can see the changing (or not) temperature in our office here:
https://smartlane.io/dataset/temperature-sensor/resource/bd645638-5541-499e-861b-f9c97e60f35a

That's an example for 'lines and points' but it works for things like bar graphs too. Last week we had people competing to achieve the best time in a remote controlled robot race where their time was automatically displayed as a bar on a 'leader board'. For good measure we had an automatically updating histogram of the times too. Updating the actual data in CKAN is easy thanks to the DataStore API.

Best Regards,

Matt

[1] https://github.com/mapbox/simplestyle-spec
[2] https://github.com/perliedman/leaflet-realtime

--

Matthew Fullerton

Freelance Software Developer und EXIST Stipend holder with the start up project "Tapestry" -http://www.smartlane.de/

[Steven De Costa]

Short answer:

Good for a blog post? yes :)

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[Adrià Mercader]

Hi Matt,

This is amazing, I'm glad the basic geospatial views have been useful as a basis for this kind of stuff. In my view both the GeoJSON styling and real time functionality should be part of ckanext-geoview, unless they add complex requirements or conflict with the most common setup. Do send your PRs!

Definitely worth a blog post, well done

Adrià

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