Provide a non-RDFa RDF Readable format for license files on spdx.org/licenses

[goneall]

To resolve issue #90 and help with issue #145, I would like to remove the RDFa dependency from the SPDX tools.

RDFa is currently used to read the license information from spdx.org/licenses.

An additional format could be added to the website which is machine readable and more efficiently parsed by the tools.

There are several formats to choose from:

1. RDF/XML
2. JSON-LD with contexts embedded in the JSON files as separate files from the current .json files
3. JSON-LD by adding contexts to the current JSON files
4. JSON-LD by adding a reference to an context file
5. RDF Turtle
6. Some other RDF format
7. any permutation of the above choices

I'm leaning towards 3 as long as it doesn't break compatibility with existing uses of JSON files. Option 4 would be cleaner and more compact, but would require the SPDX tools always be connected to the internet to run.

@kemitchell @yevster @wking thoughts?

[wking]

On Wed, Jan 10, 2018 at 11:20:40AM -0800, goneall wrote: Option 4 would be cleaner and more compact, but would require the SPDX tools always be connected to the internet to run.

Option 4 would not require an internet connection if you use a relative URI for the @Schema value.

[goneall]

Option 4 would not require an internet connection if you use a relative URI for the @Schema value.

Good point, in which case option 4 would be a better approach IMHO

[goneall]

Having a difficult time convincing the Jena library to use an external context file, so decided to go with option number 3 for now. Since we are using a library that reads both internal and external contexts, the SPDX tools code is the same for option 3 and 4. We can update the LicenseListPublisher in the future to generate files with an external context.

[goneall]

Resolved in version 2.1.12 - I'll revisit the external context in the 3.0 timeframe