European Portal addresses how to integrate real-time data into an open data platform

The European Directive 2019/1024 on open data and re-use of public sector information emphasises, among many other aspects, the importance of publishing data in real time. In fact, the document talks about dynamic data, which it defines as "documents in digital format, subject to frequent or real-time updates due to their volatility or rapid obsolescence". According to the Directive, public bodies must make this data available for re-use by citizens immediately after collection, through appropriate APIs and, where possible, as a bulk download.

To explore this further, the European Data Portal, Data.europa.eu, has published the report “Real-time data 2022: Approaches to integrating real-time data sources in data.europa.eu” which analyses the potential of real-time data. It draws on the results of a webinar held by data.europa.eu on 5 April 2022, a recording of which is available on its website.

In addition to detailing the conclusions of the event, the report provides a brief summary of the information and technologies presented at the event, which are useful for real-time data sharing.

The importance of real-time data

The report begins by explaining what real-time data are: data that are frequently updated and delivered immediately after collection, as mentioned above. These data can be of a very heterogeneous nature. The following table gives some examples:

This type of data is widely used to shape applications that report traffic, energy prices, weather forecasts or flows of people in certain spaces. You can find out more about the value of real-time data in this other article.

Real-time data sharing standards

La interoperabilidad es uno de los factores más importantes a tener en cuenta a la hora de seleccionar la tecnología más adecuada para el intercambio de datos en tiempo real. Se precisa un lenguaje común, es decir, formatos de datos comunes e interfaces de acceso a datos que permitan el flujo de datos en tiempo real. Dos estándares que ya son muy utilizados en el ámbito del Internet de las cosas (IoT en sus siglas en inglés) y que pueden ayudar en este sentido son:

SensorThings API (STA)

SensorThings API, from the Open Geospatial Consortium, emerged in 2016 and has been considered a best practice for data sharing in compliance with the INSPIRE Directive.

This standard provides an open and unified framework for encoding and providing access to sensor-generated data streams. It is based on REST and JSON specifications and follows the principles of the OData (OASIS Open Data Protocol) standard.

STA provides common functionalities for creating, reading, updating and deleting sensor resources. It enables the formulation of complex queries tailored to the underlying data model, allowing more direct access to the specific data the user needs. Query options include filtering by time period, observed parameters or resource properties to reduce the volume of data downloaded. It also allows sorting the content of a result by user-specified criteria and provides direct integration with the MQTT standard, which is explained below.

Message Queuing Telemetry Transport (MQTT)

MQTT was invented by Dr. Andy Stanford-Clark of IBM and Arlen Nipper of Arcom (now Eurotech) in 1999. Like STA, it is also an OASIS standard.

The MQTT protocol allows the exchange of messages according to the publish/subscribe principle. The central element of MQTT is the use of brokers, which take incoming messages from publishers and distribute them to all users who have a subscription for that type of data. In this type of environment, data is organised by topics, which are freely defined and allow messages to be grouped into thematic channels to which users subscribe.

The advantages of this system include reduced latency, simplicity and agility, which facilitates its implementation and use in constrained environments (e.g. with limited bandwidth or connectivity).

 In the case of the European portal, users can already find real-time datasets based on MQTT. However, there is not yet a common approach to providing metadata on brokers and the topics they offer, and work is still ongoing.

Other conclusions of the report

As mentioned at the beginning, the webinar on 5 April also served to gather participants' views on the use of real-time data, current challenges in data availability and needs for future improvements. These views are also reflected in this report.

Among the most valued categories of real-time data, users highlighted traffic information and weather data. Data on air pollution, allergens, flood monitoring and stock market information were also mentioned. In this respect, more and more detailed data were requested, especially in the field of mobility and energy in order to be able to compare commodity prices.  Users also highlighted some drawbacks in locating real-time data on the European portal, including the heterogeneity of the information, which requires the use of common standards and formats across countries.

Finally, the report provides a set of recommendations on how to improve the ability to locate real-time data sources through data.europa.eu. To this end, a series of short and medium-term actions have been established, including the collection of use cases, support for data providers and the development of best practices to unify metadata.

You can read the full report here.