Table 2.

Open source software products used in AirSensEUR.

Functionality	Products	Overview
1. Web transactions	AirSensEUR SOS-T client	Java application, pushing data (JSON POST transactions) from the host to a server when an Internet connection is available.
2. Storage	sqlite3	Local data storage on the sensor host.
	PostgreSQL/PostGIS	Server-side storage, with a database schema suitable for the $52{}^{\circ }\text{North}$ SOS implementation
3. Web services	$52{}^{\circ }\text{North}$ SOS	Implementation of an INSPIRE-compliant SOS
	$52{}^{\circ }\text{North}$ TimeSeriesAPI	RESTful interface on top of the SOS web service
4. Clients	$52{}^{\circ }\text{North}$ SensorWeb client	Mobile-friendly web client for interaction with observation data
	Geoserver	Mash-up with other geospatial data and implementation of INSPIRE discovery and view services
	RStudio (including Shiny and sensorweby)	JavaScript SOS client with functionality to process and analyze air quality data with R [29]
5. Visualization	R	Post-processing of data (e.g., for calibration or further statistical analysis)