media type / content type / MIME type for Croissant (JSON-LD "profile" parameter)

[pdurbin]

tl;dr

Can the Croissant spec be updated to formally state that the media type for Croissant is application/ld+json; profile="http://mlcommons.org/croissant/1.0" (the value from "conformsTo": "http://mlcommons.org/croissant/1.0")?

Long version

During the excellent presentation @stain gave this week on Signposting I learned that JSON-LD allows you use a "profile" parameter to help distinguish between formats that are all "application/ld+json" (such as Croissant, CodeMeta, RO-Crate, etc.).

For example, the RO-Crate docs have a section called RO-Crate JSON-LD Media type that shows the following example (note the use of "profile"):

HEAD http://example.com/ro-123/ro-crate-metadata.json HTTP/1.1
HTTP/1.1 200 OK
Content-Type: application/ld+json; profile="http://www.w3.org/ns/json-ld#flattened http://www.w3.org/ns/json-ld#compacted https://w3id.org/ro/crate"

During the call I asked what I should use for "profile" for Croissant. @benjelloun indicated I should use the value from "conformsTo": "http://mlcommons.org/croissant/1.0" like this:

Content-Type: application/ld+json; profile="http://mlcommons.org/croissant/1.0"

This makes complete sense and I'll try it but it would be nice to see this mentioned specifically in the spec. I'm happy to create a pull request if you like!

For more on the JSON-LD "profile" parameter, here's a screenshot of some docs from https://www.w3.org/TR/json-ld/#application-ld-json

[benjelloun]

Hi Phil,

Your proposal makes sense to me. I suggest we add a small section about signposting to the next version of the Croissant spec, where we recommend using profile in this way. Would you like to send a PR for that?

Best,
Omar

[pdurbin]

Sure, I'm happy to. However, profile is more generic than Signposting so maybe the PR would have two main points:

• The profile for Croissant is http://mlcommons.org/croissant/1.0
• If you want to use Signposting with Croissant, we recommend adding its profile

That is, yes, I can imagine Signposting could have its own section in the spec, but perhaps we can talk about Croissant's profile in a more generic place. 🤔

[pdurbin]

I went ahead and made a pull request (against the future 1.1 spec) to add the media type (including the profile):

• state media type for Croissant (includes profile) #801

I didn't add anything about Signposting. I'm not opposed to it but I don't want to shoehorn it in.