check media-type attribute. about nexus-bbp-domains

[MFSY]

Hi,
I would suggest the following strategy to start with media type validation:

• Users should be allowed to use string as media type value like:

"mediaType":"application/json"

This corresponds to a widely adopted way of using media types.

• The first step for validation would be to check that the providing string match IANA media type structure. The media type pattern can be seen in nexus/core/distribution and in nexus/core/mediatype schemas.

• The second step would be to check that a provided media type is in a given list. Any schema can define a list of accepted values for a property. You can extends the distribution schema in you custom entity schema like this:

{

"shapes": [
    {
      "@id": "this:DistributionShape",
      "@type": "sh:NodeShape",
      "and": [
        {
          "node":"{{base}}/schemas/nexus/core/distribution/v0.1.0/shapes/DistributionShape"
        },
        {
          "property": [
            {
              "path": "schema:mediaType",
              "in": ["application/pdf","application/json"]
            }
          ]
        }
      ]
    }
  ]
}

But this strategy comes with downsides:

• every time a new media type is added than a new schema version is needed.
• regex based validation is slow.

We can improve this strategy later by relying on types for media types.