Data and API requirements for centralized smart city platforms Foreword Contents List of figures List of tables List of abbreviations Executive summary 1 Introduction 2 Background 3 Gap Analysis on data flow standardization 3.1 International Data spaces: strategies and choices 3.2 Gaia-X 3.3 FIWARE Foundation 3.4 SAREF 4 The centralized concept of “smart city as a hub” 4.1 Connecting the data sources: the SC Hub’s architecture 4.2 Similarities and differences of SCHub with ETL 4.3 SCHub in the interoperability initiatives landscape 4.4 Connecting people and materials: an innovation and supply chain hub 5 Use Cases 5.1 Data collection of common property measurements 5.2 Sensor measurement data discovery 5.3 Retrieval of sensor measurements using a unified API 6 Conclusions: integration with the SSC platform References