Documentation and
common services
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Technical Design Documents
The technical and operational specifications of the Once-Only Technical System, laid down in the Commission’s Implementing Regulation ((EU) 2022/1463) setting out the system, are complemented by detailed, non-binding technical design documents jointly prepared by the Commission and Member States.
Chapter 1
Introduction - High Level
Architecture
This chapter introduces the high-level architecture of the Once-Only Technical System and the key concepts and themes found in the subsequent chapters.
Chapter 2
User Identification, Authentication and Record Matching
This chapter explains how those submitting or receiving evidences through the Once-Only Technical System are identified and authenticated.
Chapter 3
Common Services
This chapter looks at the Common Services necessary for the proper execution of the evidence exchange process. You can also learn more about APIs supporting these common services.
Chapter 4
Evidence Exchange
This chapter introduces evidence exchange in the Once-Only Technical System, which is based on bilateral data exchange between relevant authorities.
Chapter 5
Data Models
This chapter looks at the data models that streamline the exchange of evidences, together with a methodology for defining new data models and code lists.
Chapter 6
OOTS Guidance & UX
Recommendations
This chapter provides an overview of how the Once-Only Technical System works as part of the wider Single Digital Gateway and looks at the first set of UX recommendations.
Common services
The Commission provides Common Services to help the Member States ensure the proper exchange of evidences.
Data Service Directory
The Data Service Directory is a common service that acts as a catalogue of evidence types that can be provided upon request.
Evidence Broker
The Evidence Broker is an authoritative system that maps specific data sets as evidence types that prove specific requirements.
Semantic Repository
The Semantic Repository is a common service that acts as a data portal for the technical system.
Supporting services
Testing service
The OOTS Testing service assists national teams in implementing the Once-Only Technical System. Information on available testing services, including the test platform and other tools to facilitate testing are available on a restricted wiki space.
If required, please request access to the restricted wiki via the Service Desk.
Contact the service desk on EC-OOTS-SUPPORT@ec.europa.eu
Service desk
The Service Desk helps users improve the performance, continuity and reliability of their Once-Only Technical System implementations.