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How to use the NFDI4ING Knowledge Graph Explorer

While the NFDI4ING Knowledge Graph Explorer (KGE) allows filtering the content of the knowledge graph via any attribute contained in the knowledge graph, it is advisable to start by selecting a metadata profile that fits the kind of content you are interested in.

  1. Pick a metadata profile from the "Profile" dropdown selector at the left side of the screen. You can search for profiles by typing a name, e.g. "sample preparation".
  2. Upon selecting a profile, the search facets on the left are reduced to attributes contained in the profile. Available search facets fall in to three categories:
    1. Numerical values - these are displayed as sliders to specify the minimum and maximum values you are interested in.
    2. Lists of options - if options fall into a controlled list of options, e.g. units or entities in the knowledge graph, a single option can be selected in the corresponding drop down menu
    3. Free text - if a value is neither numerical nor limited by a controlled list, you can perform a full-text search by entering your search phrase in the "Full-text search" form at the top left of the screen. This will search within all fields containing free text.
  3. If several search options are offered under one heading in the search facets, they correspond to the same attribute. A typical case are physical quantities, e.g. "duration (cooling)", which combine a numerical value with a physical unit.
  4. After specifiying your filtering criteria in the search facets, the results in the center column of the screen are narrowed down to instances of the selected profile that match your criteria.
  5. When selecting a result by clicking on it in the center column, it is displayed at the right side of the screen. You can switch between a "Graph view" and a tabular "Detail view" by selecting the corresponding headers. In the tabular "Detail view", colored bars at the left side help to keep track of the indentation. This is important for modular data structures, e.g. a parameter of a tool used in a step of a multi-step process, in which each modular entity is represented by its own metadata profile.

API endpoints

The NFDI4ING Knowledge Graph Explorer exposes several API endpoints, most notably for querying the graph with SPARQL. Please refer to the API documentation for details.

Planned features

The NFDI4ING Knowledge Graph Explorer is under active development. Features planned for the future are

  • Tidy up the data entry form by hiding optional fields when entering and editing data.
  • Implement search functionality for linking to existing nodes in the knowledge graph when entering and editing data. Currently, one can only select available nodes according to their name or IRI.
  • Index RDF from external triple stores to enable read-only-access to the NFDI4ING federated knowledge graph.
  • Enable unit conversion in facetted search via numerical parameters.

F.A.Q.

How can I publish my data in the NFDI4ING knowledge graph?

In order to assure the quality of the information in the knowledge graph, only administrators assigned by NFDI4ING may add data to the knowledge graph. If you want to publish your data in the NFDI4ING knowledge graph, contact us via the NFDI4ING helpdesk.

How can I edit existing entries in the NFDI4ING knowledge graph?

Only adminstrators can edit data in the knowledge graph.

What are Metadata Profiles?

The metadata profiles used by the KGE are sets of rules that describe what information is necessary for describing a certain scientific use case as well as with which terms that information is supposed to be expressed. Technically, they are realised as SHACL shapes and rely on terms from NFDI4ING's common information model to formulate use-case-specific templates for metadata that can be added to the NFDI4ING knowledge graph.

Apart from specifying a target format and providing a means for quality control and validation of metadata, the KGE uses these metadata profiles for creating web forms, i.e. tabular views of the RDF data, which can be used for editing and displaying entries in the knowledge graph. They also support a search mechanism in which entries in the knowledge graph are indexed according to the attributes specified in the corresponding metadata profile. This enables a precise facetted search within the knowledge graph without knowledge of SPARQL.

Where do I find Metadata Profiles suitable for my research?

The NFDI4ING Metadata Profile Service is NFDI4ING's platform for creating, sharing, curating and reusing metadata profiles. Apart from hosting metadata profiles created and recommended by NFDI4ING, it offers a graphical user interface for creating and managing metadata profiles using terms recommended ontologies as building blocks.

What is the technological basis of the NFDI4ING Knowledge Graph Explorer?

The source code underlying the KGE is available under MIT license:
https://github.com/ULB-Darmstadt/rdf-store

Does the knowledge graph contain actual research data?

The NFDI4ING knowledge graph is a RDF graph providing metadata information on available research data in the engineering community. It does not directly contain research data in the sense of file objects, but contains links to files published at other locations like research data repositories.

Is it possible to publish non-engineering data in the KGE?

The KGE's technology is domain agnostic. If you feel your data is synergistic to information contained in the NFDI4ING knowledge graph, feel free to contact us to explore opportunities to include more data in the NFDI4ING knowledge graph or combine knowledge graphs from other disciplines.