Add the generated RDF files

[zvr]

We used to have a top-level directory ontology in this repo, containing the RDF data. It was removed because it was stale.

This PR adds this data back, in a new top-level directory named rdf.

This includes the ontology, but also the JSON-LD context file.

Signed-off-by: Alexios Zavras github@zvr.gr

[bobmartin3000]

LGTM

[bact]

Does it possible to take this opportunity that the URL is going to change anyway (because of the patch version update), to have this file rdf/spdx-model.json-ld renamed to rdf/spdx-model.jsonld please?

The reason is, with that we can have the extension that is consistent with rdf/spdx-context.jsonld and authors will not have to remember when to use .json-ld or when to use .jsonld.

I have checked in both spdx-spec and spdx-3-model repos,

• there are at least 25 instances of spdx-context.jsonld
• there's only one instance of spdx-model.json-ld, which is in the README section, and not the spec or the code:
  

  spdx-spec/README.md

  Lines 156 to 162 in 399bbf5

  	This will create well-formatted model files in the `spdx-spec/docs/model/`
  	directory. This directory contains two components:
  	- Model ontology and diagram files: These files (`model.plantuml`,
  	`spdx-context.jsonld`, `spdx-model.dot`, `spdx-model.json-ld`,
  	`spdx-model.pretty-xml`, `spdx-model.ttl`, `spdx-model.xml`)
  	are ready for immediate use.

  
  Current instances that reference to the SPDX model use spdx-model.ttl.

This means the change to standardize .jsonld will not be a breaking one.

Thank you for generating and adding these files back.

[zvr]

Of course the filename can easily be changed, but let's be careful here:
we do not want to encourage people using these files automatically from the repo.

The idea is to simply have them for people to view (most probably via the GitHub web UI). It should not be considered a distribution mechanism of generated artifacts.
(we have had this problem before)

[bact]

Thanks. +1 on "It should not be considered a distribution mechanism of generated artifacts."

I think in general, some consistency/common expectability will help us the developers as well, not only the "end-users".

[zvr]

I've now added all the various formats that RDF data can be automatically generated.

[bact]

Thank you. I think we can merge this.