JSON-LD is a JSON-based format to encode RDF graphs. Its documentation can be found here.
The JSON-LD is an RDF format and follows the serialization rules of the SPDX RDF serialization specification.
The following SpdxDocument properties are mapped to native JSON-LD mechanisms defined within the JSON-LD syntax specifications. Any properties not listed below should be serialized as part of the SpdxDocument element itself within the JSON-LD serialized data.
Deserialization of any JSON-LD serialized SPDX content MUST expand the inverse of these native mappings such that the logical SpdxDocument element directly contains its full set of properties.
The namespaceMap uses the term to IRI mapping in the JSON-LD context.
The graph objects @graph
lists the elements for the SpdxDocument.
The RDF graph of an instance of the SPDX model shall contain all Element nodes (i.e. objects that are subclasses of Element) as a list on top-level under the "@graph" key. This means that all references to Element nodes have to use the URI of the referenced Element.
Inlining/Embedding of Element nodes into other nodes is not allowed.
On the other hand, non-Element nodes (like those of type "ExternalReference" or similar complex data classes) have to be inlined (TODO: we may want to make an exception for CreationInfo, depending on the outcome of the surrounding discussion).
The SPDX organization provides a global JSON-LD @context file that MUST be used universally for all SPDX JSON-LD files of a given SPDX version.
The context is available under https://spdx.org/rdf/3.0.0/spdx-context.jsonld and should be included in serialized files on top-level via
"@context": "https://spdx.org/rdf/3.0.0/spdx-context.jsonld"Take special note that this context defines aliases for better compatibility with the SPDX model. In particular, these are "spdxId" for "@id" and "type" for "@type".
Further custom namespace mapping can be included in the context in a separate object, see for example here.
An SPDX serialization in JSON-LD is considered valid if it validates against the OWL ontology which also includes SHACL shape restrictions.
The ontology is automatically generated from the specification markdown files and can be found at https://spdx.org/rdf/3.0.0/spdx-model.ttl.
The code that generates the ontology is located at https://github.com/spdx/spec-parser.