OGC Web APIs to Make Data Available in the Green Deal Data Space

The Green Deal Data Space is born in the big data paradigm where sensors produce constant streams of Earth observation data (remote sensing or in-situ). The traditional and manual organization of data in layers is no longer efficient as data is constantly evolving and mixed together in new ways. There is a need for a new organization of the data that favors users and in particular can be considered ready for use. The AD4GD project proposes a threefold solution: A new information model, dynamic multidimensional datacubes and OGC APIs for data query and filtering. The use of data in the context of the Green Deal is difficult due to the wide heterogeneity of data sources (many times expressed in different data models) and different semantics used to represent data, and the lack of sufficient interoperability mechanisms that enable the connection of existing data models. The solution is a framework composed by a suite of ontologies implemented in line with best practices, reusing existing standards and well-scoped models as much as possible and establishing alignments between them to enable their interoperability and the integration of existing data. This approach was successfully applied to object based data stored in a RDF triple store e.g. vector data and sensor data) in the agricultural sector. The traditional representation of static two-dimensional layers needs to be replaced by a dynamic view where time becomes an extra dimension. In addition, other dimensions emerge such as the height in atmospheric and oceanic models, the frequency in hyperspectral remote sensing data or the species in a biodiversity distribution model. These dimensions define a data cube that offers an entry to a constantly evolving world. The dimensions in the datacube as well as the values stored in the cube cells (a.k.a. attributes) should be connected to the concepts in the Information Model. In the big data paradigm access to individual layers is difficult due to the dynamic nature of the data. Instead we need a set of modern APIs as an entry point to the data in the data space. The OGC APIs offer a set of building blocks that can be combined together with other web API design principles to build the Green Deal Data Space data access APIs. Users will be able to get the necessary data for modeling and simulating the reality using the OGC APIs endpoints described in the OpenAPI description document. The OGC APIs include the concept of collections as an initial filtering mechanism but a filtering extension using CQL2 is in advanced draft status. It is fundamental that the OGC APIs are also capable of generating detailed metadata about the extracted subset including data sources, producer information and data quality estimations. AD4GD is a Horizon Europe project co-funded by the European Union, Switzerland and the United Kingdom.