Reconsider optional metadata of resources such as media-type and size

[laurensdeb]

Just noting that "the media type of a resource" is an ill-defined notion.

Not blocking for this PR, but I suggest that we add a section about Data Resources in Section 7, where we state that a Data Resource has a "main" representation (the one POSTed or later PUT by the client) with a specific media-type. Servers would still be allowed to serve alternative representations with different media-type using conneg.

Originally posted by @pchampin in #81

[acoburn]

Some additional context for this: these are values that may appear in a container listing but whose (literal) values are not appropriate for link headers. In general, these values will be included in other HTTP headers (e.g., Content-Type and Content-Length). For content-negotiation, these values may be dynamically generated.

[acoburn]

At present, the spec includes examples such as:

{
  "@context": "https://www.w3.org/ns/lws/v1",
  "id": "/alice/notes/",
  "type": "Container",
  "totalItems": 1,
  "items": [
    {
      "type": "DataResource",
      "id": "/alice/notes/shoppinglist.txt",
      "mediaType": "text/plain",
      "size": 47,
      "modified": "2025-11-24T12:00:00Z"
    }
  ]
}

This implies that a resource has a media type, which is not strictly true: a representation has a media type. An alternative way to represent this data could be:

{
  "@context": "https://www.w3.org/ns/lws/v1",
  "id": "/alice/notes/",
  "type": "Container",
  "totalItems": 1,
  "items": [
    {
      "type": "DataResource",
      "id": "/alice/notes/shoppinglist.txt",
      "representations": [{
          "mediaType": "text/plain",
          "size": 47
      }],
      "modified": "2025-11-24T12:00:00Z"
    }
  ]
}

[elf-pavlik]

Could someone please help me understand how this issue and

• Handling of non-URI structured metadata in specification text #89

relate?

Are we talking about having different ways of serializing the same description e.g. content-type & size, in application/lws+json and application/linkset?

[elf-pavlik]

During the call we also noticed that https://w3c.github.io/lws-protocol/lws10-core/#contained-resource-description

A contained resource description SHOULD include:

• mediaType: The media type of the resource (e.g., "text/plain", "image/jpeg"). MUST be present for DataResources.

So we have SHOULD and then (nested?) MUST. Is it common and does it imply that if implementation conforms to SHOULD then it also needs to conform to that MUST?
Does it affect manifests in test suite?

• LWS Test Suite #102