One of the key objectives of the project as regards technology, was to develop a generic federated OOP architecture. However, in light of the SDGR, the project also developed a detailed, directly implementable technical specifications included in TOOP Solution Architecture that could be directly re-used by the EC and MS implementing the SDGR. As a result, the project produced the following technical outputs:
• TOOP Reference Architecture;
• TOOP Solution Architecture;
• Software Components that physically implement TOOPSA and could be used in pilot environments by participating MS, as well as a set of testing tools needed for onboarding pilots and verification of end-to-end transaction capabilities achieved by each MS system connected to TOOP;
• Domain-specific profiles and implementation areas in pilot Working Groups: eProcurement, General Business Mobility, and Maritime.
The TOOP components, solution architecture and reference architecture were piloted in three pilot domains: eProcurement, General Business Mobility (GBM), and Maritime. The different pilot domains identified potential use cases suitable for showing off the OOP, defining the goals and anticipated benefits of TOOP based on motivational scenarios and process analyses and providing requirements for the TOOP Reference and Solution Architectures. For the GBM domain in particular, requirements were also provided from the SDGR. These requirements guided the development of TOOP specifications and TOOP components, the Member States deployed TOOP specifications and components and took part in various connectathons in order to demonstrate the OOP.
In addition to the technical work outlined above, the project dedicated significant energy and efforts to sustainability and adoption of the once-only principle. This work included analysing drivers and barriers for adoption of the OOP, impact assessments, as well as sustainability and governance aspects. One of the results of this work, is that the EC should further manage and organise the processes of governance of TOOP solutions such as reference architecture. The uptake of TOOP outcomes by CEF has been a first step in this direction. It is important to keep the results in line with the requirements of the SDGR, relevant implementing acts and other relevant legal acts. The combination of the involvement of EC/CEF on the one hand and the ONCE-ONLY.ORG on the other hand can ensure the necessary experiences and resources that are required. CEF has already taken up other outcomes from previous Large-Scale Projects and has gained the knowledge to maintain and further develop outcomes of LSPs.
In order to ensure the sustainability and uptake of the developed components that have not been taken over by CEF Digital, an independent organisation - ONCE-ONLY.ORG AISBL - was endorsed by the General Assembly of TOOP. ONCE-ONLY.ORG is a flexible organisation that can ensure the involvement of public administrations from a number of different countries, businesses, academia, and standardisation bodies. Together, they can provide the support required over a long-term basis to keep the results of TOOP aligned with the requirements of evolving legal acts, especially the SDGR, but also eIDAS and the GDPR, and help to fulfil the expectations of key stakeholders.
To present the results of the project, the TOOP consortium published a book titled “The Once-Only Principle: The TOOP Project” and published by Springer. The book describes and documents the developments and results of the Once-Only Principle Project. It includes the OOP definition and objectives in the EU policies, barriers and opportunities for the OOP in Europe and some examples of OOP best practices in Europe. Moreover, it highlights the OOP legal landscape and legal interoperability within the EU as well as describing the roots of OOP in the various Member States and the technical challenges for applying OOP across the EU and TOOP. The last part of the TOOP Book is about OOP architecture, OOP piloting and testing methodology, measuring potential impacts of the OOP for businesses across national boundaries and gives an outlook of the future of OOP in Europe.
