The Interoperability Test Bed has been selected since early 2022 as the main conformance testing service for the OOTS. It is complemented by peer-to-peer testing through OOTS Projectathons, of which the first successful event was carried out in Brussels between the 19th and 21st of April 2023.

The Once-Only Technical System (OOTS)  is a technical framework for data sharing that acts as the backbone of the Single Digital Gateway. As of the end of 2023, citizens and businesses will be able to request official documents (known as “evidence”) to complete administrative procedures allowing people to study, work, live and retire in other EU countries through seven simple steps. The decentralised architecture connects public authorities, enabling them to exchange evidence at the citizen's or business' request. Complementing the Member States’ endpoints, the OOTS uses shared data models and common supporting services put forth by the European Commission, to facilitate the discovery and exchange of evidence for supported procedures.

The cross-border flow of information enabled by the OOTS is only made possible through the interoperability of each connected endpoint. This places high importance on the conformance testing of Member State implementations to ensure common data models and services are correctly used, and that foreseen processes are implemented consistently. Conformance testing for the OOTS is foreseen along two tracks:

• Standalone tests for National endpoints against predefined test scenarios using simulated endpoints, APIs and test data.
• Peer-to-peer tests through “Projectathon” events where National endpoints exchange requests and responses with each other.

The Interoperability Test Bed has been supporting the OOTS since February 2022 along both conformance testing tracks. The first important testing milestones for the OOTS came with the publishing of the initial version of its conformance testing service and the successful completion of the first OOTS Projectathon in April 2023.

Standalone conformance testing

Since February 2022, the Interoperability Test Bed is foreseen as the main conformance testing service for the OOTS. Testing focuses on National implementations in a standalone manner, testing each endpoint against simulated services realising the OOTS common service APIs and simulated National peer endpoints. Simulation is used to allow for maximum specification coverage and verification of scenarios that would be difficult to consistently reproduce when using real-world implementations. Tests are organised in test suites that focus on:

• Use of simulated common services to test the discovery of requirements, evidence types, and data services.
• Use of simulated National endpoints to test the exchange of evidence documents over eDelivery.

The eventual service is envisioned to be provided through the shared Test Bed instance operated by DIGIT. At present, a preview of this service is made available to Member States as a separate OOTS-specific environment – informal in nature – providing test suites for self-service experimentation rather than formal testing.

This service is complemented by a public OOTS validator allowing developers to validate data against the OOTS common data models. These cover request and response messages for evidence brokers, data service directories, and lifecycle management interfaces.

The validator may be used via web user interface, as well as REST and SOAP APIs for machine-to-machine integrations. It is a configuration of the Test Bed’s generic XML validator, configured with the XML Schemas and Schematron validation artefacts defined as part of the OOTS specifications.

Peer-to-peer testing and the first OOTS Projectathon

Complementing the standalone conformance testing service, a series of OOTS Projectathons are foreseen as peer-to-peer testing events and opportunities for community building.

The first OOTS Projectathon was carried out between the 19th and 21st of April 2023, providing an opportunity for National administrators to meet and discuss between themselves and with experts from the European Commission. During the event, National development teams were engaged in a marathon of peer-to-peer testing for their endpoint implementations. A total of 25 countries participated either as active test participants or observers, with 186 staff including administrators, developers, and support engineers, joining onsite or remotely. National participants were supported by experts from the European Commission and Kereval, a service provider with significant experience carrying out similar testing events in the eHealth domain (the IHE Europe Connectathons).

The Interoperability Test Bed is supporting OOTS Projectathons by providing validation services used for the live verification of data exchanged between National endpoints. These services are integrated into the Gazelle testing platform, the software used to pair together National endpoints and assign them appropriate test scenarios. Interestingly, this is not the first time the Test Bed’s validators are used in such events, given that as of September 2022 they are also supporting IHE Europe Connectathons.

Leading up to the first Projectathon, the previously mentioned OOTS Test Bed instance was adapted to provide test suites aiming to best prepare participants for the peer-to-peer tests. Although foreseen as an optional step, National administrations were advised by the European Commission to first validate their implementations in a standalone manner, ensuring that the limited time during the Projectathon itself was used in the most effective way.

Next steps

Following the first OOTS Projectathon of April 2023, two additional Projectathon events are foreseen before the legislation comes into force:

• The second OOTS Projectathon shall take place in June 2023, providing a valuable moment when national implementation teams can engage again in peer-to-peer tests prior to the summer recess.
• The third OOTS Projectathon shall take place in October 2023, just two months before the legal deadline, as the final critical peer testing event towards Europe’s Once-Only journey.

In parallel to these events, the OOTS Test Bed instance shall remain continuously available to National development teams, allowing implementations to be tested in a self-service manner, and to best prepare for upcoming Projectathons. The test suites offered are also expected to be further elaborated to maximise specification coverage, with a planned move to the DIGIT shared Test Bed instance as the final platform to host the OOTS conformance testing service.

Find out more

The Once-Only Technical System represents a key step in simplifying the administrative burden for citizens and businesses when using public services within Europe. To find out more about the OOTS vision, use cases, architecture and roadmap, you are invited to connect to the Once-Only Hub, the starting point for all relevant information, news and technical documentation.

Regarding the Test Bed, general details on its services can be found in its Joinup space, with its value proposition being a good starting point for newcomers. Information on setting up validators, such as the validator configured for the OOTS data models, is available through detailed guides based on the underlying data syntaxes (see for XML, RDF, JSON and CSV cases). Finally, if you are interested in receiving the Test Bed’s news, apart from subscribing to notifications, you may also follow the Interoperable Europe’s social media channels (Twitter, LinkedIn) for updates on the Test Bed and other interoperability solutions.