The Once Only Hub. Collaborate to build the first EU Data Space.
The Once Only Technical System (OOTS) is the first EU cross-domain data space for secure government-to-government data exchange.
To make OOTS a reality, the European Commission established the Once Only Hub (OOHUB), a space for implementors where they can discover and access all the services provided by the European Commission to implement the Once Only Technical System.
Who's the HUB for?
SDG coordination group
Responsible for the implementation of OOTS in their member state.
Competent authorities
The authorities which must allow their users to retrieve requested evidence using OOTS.
Solution providers
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How does OOTS work?
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Learn more about OOTS in our guidance report.
Technical documentation
The technical and operational specifications of the Once Only Technical System (OOTS), laid down in the Commission’s Implementing Regulation setting out the system, are complemented by detailed, non-binding technical design documents (TDDs) resulting from the common efforts of the Commission and Member States.
Chapter 1
Introduction - High Level Architecture
This chapter provides a high-level overview of the architecture of the Once-Only Technical System (OOTS) of the Single Digital Gateway (SDG) and serves as an introduction to all technical design documents.
Chapter 2
User Identification, Authentication and Record Matching
This chapter deepdives into the use and purpose of the eID Building Block and eIDAS attributes in the Once-Only Technical System to support user identification and authentication.
Chapter 3
Common services
This chapter provides the information model and technical documentation of the identified Common Services, which are the Data Service Directory, the Evidence Broker and the Semantic Repository.
Chapter 4
Evidence Exchange
This chapter describes correlated messages and how the Once-Only Technical System (OOTS) specifications define in detail the structure, content and message exchange parameters.
Chapter 5
Data Models
This chapter has coveres the semantic interoperability issues in designing the single technical system for the SDG and ensuring its interconnection with EU Member States' IT systems and EU-level systems.
Chapter 6
OOTS Guidance & UX Recommendations
This chapter provides a high-level overview of how the Once-Only Technical System (OOTS) of the Single Digital Gateway (SDG) works as well as detailed UX recommendations.
Common services
The common services are necessary for the proper execution of the evidence exchange process.
Evidence Broker (EB)
This service is an authoritative system that maps specific data sets as Evidence types that prove specific requirements. The consults the to find which types of evidence can be requested as evidence for a specific Evidence Subject, taking into account the Subject's location and/or jurisdiction.
Data Service Directory (DSD)
This common service acts as a catalogue of Evidence types that the can provide upon request. It is used in the Evidence Exchange process by the Evidence Requesters to discover the Evidence Providers that can provide the evidence they require.
Semantic Repository (SR)
This common service that act as a data portal for OOTS, storing commonly agreed information models grouped by domain, providing them under multiple representation techniques.
Supporting services
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Testing
The goal of the OOTS Testing services is to assist Member State teams in implementing the Once-Only Technical System (OOTS) as defined in the Implementing Regulation (IR) and Technical Design Documents (TDDs). Information on the available testing services, including the test platform and tools to facilitate testing can be found on the following protected wiki space
Member State teams that would like to get access are invited to contact their National Coordinator or the EC OOTS Support Desk via mail: EC-OOTS-SUPPORT@ec.europa.eu
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Collaborate with us
As part of the SDG coordination group
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As an expert in our subgroups
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Service desk
The service desk helps Contributors get access to the Confluence and answers to any technical issues. Contributors are added to specific user groups which allow them to see the dedicated pages of the sub-groups they are working on.