In Sweden, Trafikverket (Swedish Transport Administration) have a country wide network of weather stations to monitor road conditions. The primary purpose is to use data for managing of roads, but data is available through an Open API.
This implementation reads data from selected station recurrently (when new data is produced) and store into a file. The implementation store and plot 24 hours of data at most. At the same time it reads progonse data from SMHI
As an example, weather data for station "Lund N" is here
Any station available can be read by using its name, refer to this map and zoom in to find the right name. Data from SMHI uses the coordinates from the station.
To use the API, an authorization key is needed, a registration
is needed (free of charge). The key is available there.
Place the key in file auth.yml (in the same directory as ws.py) using syntax:
auth:
key: 71fa8aa80d...
There are some specifics to the implementation described below.
Trafikverkets servers use Server Side Events (SSE) to subscribe for data. For this purpose, the implementation use sseclient in a loop.
As the connection is exposed to reset-errors the value of eventid from the server needs to be passed as parameter value
to lasteventid to re-establish the connection.
A typical frequency of new data is every 10 minute (but might vary between stations).
The frontend (webpage) use bootstrap and highcharts to display data.
ws_emitter.py is the server process, using flask and templates to generate HTML. At a request to Index ("/"), flask
render the template ws.html. These libraries are loaded:
- bootstrap and bootstrap-icons
- jQuery dataTables
- highcharts and highcharts windbarb
- D3
- Leaflet
Layout of UI is done through bootstrap, plotting through highcharts and a table of data through jQuery. Map for position of station is done through leaflet. Special care is taken to draw a windrose, D3 is used to create the bins for the histogram used as input for the Windrose.