Introduction

  • RO-Crate provides a structure to make FAIR data packages
  • schema.org in JSON-LD provides a controlled vocabulary for FAIR metadata
  • Each entity of the crate is described separately
  • Cross-references between entities create a graph
  • The RO-Crate specification recommends which types and keys to use

Turning a folder into an RO-Crate

  • Adding a RO-Crate Metadata file to a folder turns it into an RO-Crate
  • The RO-Crate Root is the top-level folder of the crate
  • RO-Crate uses schema.org as base vocabulary
  • The JSON-LD context enables optional Linked Data processing
  • Descriptions are listed flatly as entities in the @graph array

Making a metadata descriptor

  • The RO-Crate Metadata Descriptor describes the JSON-LD file itself
  • RO-Crate specifications are versioned
  • The version of RO-Crate is indicated using the conformsTo property

Declaring the root folder

  • The RO-Crate Root is the top-level object of the RO-Crate
  • The root identifier may be a URL, but commonly just ./ for the current folder

Describing the root entity

  • Name, description, date published and license are required for the RO-Crate Root”
  • RO-Crate allows multiple licenses for different parts

Adding cross-references

  • The @id uniquely identifies the entity within the RO-Crate
  • The @id key is used for cross-referencing
  • Multiple types can be listed by using an array

Data entities

  • Data entities are files & folders within the root, as well as external Web references
  • Required properties for files are name and encodingFormat
  • License can be overridden for particular data entities

Contextual entities

  • Contextual entities are not considered part of the crate
  • Cross-references should be expanded as contextual entities
  • It is recommended to provide a human-readable name for licenses

Authorship in crates

  • Authors are described as separate entities
  • Organization entities can be shared by multiple persons having the same affiliation
  • Crate authors made (some) of the crate’s content
  • Publishers of an RO-Crate are typically organizations

Validating JSON-LD

  • RO-Crate metadata files are valid JSON-LD
  • The JSON-LD Playground can do basic validation and visualization
  • Further use of RO-Crate as Linked Data is possible, but may require handling of relative URI references

Converting JSON-LD to triples

  • The JSON-LD @context maps JSON keys to schema.org vocabulary
  • A @base URI is needed to make absolute URIs
  • arcp and UUID can be used for RO-Crates that are not exposed on the Web

Visualizing a crate as HTML preview

  • RO-Crate can be rendered into a HTML preview
  • RO-Crate previews tend to show each entity separately
  • The preview HTML can be added as part of the RO-Crate

Completed RO-Crate

  • A single RO-Crate lists all the entities
  • The order of entities in the @graph array is not important

Next steps

  • RO-Crate specification has further details, e.g. additional contextual entities