Sinoptik

Sinoptik is a (REST) API service that provides an API for today's weather forecast. It can provide you with a specific set or all available metrics that it supports.

Currently supported metrics are:

• Air quality index (per hour, from Luchtmeetnet)
• NO₂ concentration (per hour, from Luchtmeetnet)
• O₃ concentration (per hour, from Luchtmeetnet)
• Particulate matter (PM10) concentration (per hour, from Luchtmeetnet)
• Pollen (per hour, from Buienradar)
• Pollen/air quality index (per hour, from Buienradar)
• Precipitation (per 5 minutes, from Buienradar)
• UV index (per day, from Buienradar)

Because of the currently supported data providers, only data for The Netherlands can be queried.

Building & running

Using Cargo, it is easy to build and run Sinoptik, just run:

$ cargo run --release
...
   Compiling sinoptik v0.1.0 (/path/to/sinoptik)
    Finished release [optimized] target(s) in 9m 26s
     Running `/path/to/sinoptik/target/release/sinoptik`

(Note that Rocket listens on 127.0.0.1:3000 by default for debug builds, i.e. builds when you don't add --release.)

You can provide Rocket with configuration to use a different address and/or port. Just create a Rocket.toml file that contains (or copy Rocket.toml.example):

[default]
address = "0.0.0.0"
port = 2356

This will work independent of the type of build. For more about Rocket's configuration, see: https://rocket.rs/v0.5-rc/guide/configuration/.

Forecast API endpoint

The /forecast API endpoint provides forecasts per requested metric a list of forecast item which are each comprised of a value and its (UNIX) timestamp. It does so for a requested location.

Locations

To select a location, you can either provide an address, or a geocoded position by providing a latitude and longitude. For example, to get forecasts for all metrics for the Stationsplein in Utrecht, use:

GET /forecast?address=Stationsplein,Utrecht&metrics[]=all

or directly by using its geocoded position:

GET /forecast?lat=52.0902&lon=5.1114&metrics[]=all

Metrics

When querying, the metrics need to be selected. It can be one of: AQI, NO2, O3, PAQI, PM10, pollen, precipitation or UVI. If you use metric all, or all is part of the selected metrics, all metrics will be retrieved. Note that the parameter "array" notation as well as the repeated parameter notation are supported. For example:

GET /forecast?address=Stationsplein,Utrecht&metrics[]=AQI&metrics[]=pollen
GET /forecast?address=Stationsplein,Utrecht&metrics=AQI&metrics=pollen
GET /forecast?address=Stationsplein,Utrecht&metrics=all

Forecast responses

The response of the API is a JSON object that contains three fixed fields:

• lat: the latitude of the geocoded position the forecast is for (number)
• lon: the longitude of the geocoded position the forecast is for (number)
• time: the (UNIX) timestamp of the forecast, basically "now" (number)

Then, it contains a field per requested metric with a list of forecast items with two fixed fields as value:

• time: the (UNIX) timestamp for that forecasted value (number)
• value: the forecasted value for the metric (number)

An example when requesting just UVI (because it's short) for some random position:

{
  "lat": 52.0905169,
  "lon": 5.1109709,
  "time": 1652188682,
  "UVI": [
    {
      "time": 1652140800,
      "value": 4
    },
    {
      "time": 1652227200,
      "value": 4
    },
    {
      "time": 1652313600,
      "value": 4
    },
    {
      "time": 1652400000,
      "value": 4
    },
    {
      "time": 1652486400,
      "value": 5
    }
  ]
}

Combined metric PAQI

The PAQI (pollen/air quality index) metric is a special combined metric. If selected, it merges items from the AQI and pollen metric into PAQI by selecting the maximum value for each hour:

{
  "lat": 52.0905169,
  "lon": 5.1109709,
  "time": 1652189065,
  "PAQI": [
    {
      "time": 1652187600,
      "value": 6.09
    },
    {
      "time": 1652191200,
      "value": 6.09
    },
    ...
  ]
}

Errors

If geocoding of an address is requested but fails, a not found error is returned (HTTP 404). with the following body (this will change in the future):

{
  "error": {
    "code": 404,
    "reason": "Not Found",
    "description": "The requested resource could not be found."
  }
}

If for any specific metric an error occurs, the list with forecast items will be absent. However, the errors field will contain the error message for each failed metric. For example, say Buienradar is down and precipitation forecast items can not be retrieved:

{
  "lat": 52.0905169,
  "lon": 5.1109709,
  "time": 1654524574,
  ...
  "errors": {
    "precipitation": "HTTP request error: error sending request for url (https://gpsgadget.buienradar.nl/data/raintext?lat=52.09&lon=5.11): error trying to connect: tcp connect error: Connection refused (os error 111)"
  }
}

Map API endpoint

The /map API endpoint basically only exists for debugging purposes. Given an address or geocoded position, it shows the current map for the provided metric and draws a crosshair on the position. Currently, only the PAQI, pollen and UVI metrics are backed by a map.

For example, to get the current pollen map with a crosshair on Stationsplein in Utrecht, use:

GET /map?address=Stationsplein,Utrecht&metric=pollen

or directly by using its geocoded position:

GET /map?lat=52.0902&lon=5.1114&metric=pollen

Map responses

The response is a PNG image with a crosshair drawn on the map. If geocoding of an address fails or if the position is out of bounds of the map, nothing is returned (HTTP 404). If the maps cannot/have not been downloaded or cached yet, a service unavailable error is returned (HTTP 503).

License

Sinoptik is licensed under the MIT license (see the LICENSE file or http://opensource.org/licenses/MIT).