Let Annotations be schema:Things

[musicog]

As discussed with @alastair, model TROMPA Web Annotations as Things (as well as Annotations), probably using additionalType, so that we can store them within ItemLists

[alastair]

@musicog can you explain a bit more detail how additionalType may work?
At the moment when we render an item to json-ld, its type is that which is defined a the top of the schema file.
For example, a DigitalDocument is defined as being both a Thing and a CreativeWork:
https://github.com/trompamusic/ce-api/blob/staging/src/schema/type/DigitalDocument.graphql

We've not been mandating that these items also have the additionalType field filled (as a single item, as a list?). In this case, is it mandatory that we add both schema.org/Thing and schema.org/CreativeWork to the additionalType field when rendering to json-ld? Where should this be done? Should it be done only in the json-ld renderer? Should we require that this field is always set in mutations? Can we automatically fill it in somehow using the graphql-neo4j bindings that we use?

[musicog]

Your example specifically does not require additionalTypes to be specified since schema:DigitalDocuments are rdfs:subClassOf schema:CreativeWork (which are in turn rdfs:subClassOf schema:Thing) -- see https://schema.org/DigitalDocument.ttl and https://schema.org/CreativeWork.ttl

However, oa:Annotations are not rdfs:subClassOf schema:Thing, since schema.org and the Web Annotations Data Model are not (explicitly, formally) interlinked. Hence why we need to take the trouble to specify the additionalType.

In other words, a web client application that cares about semantics ought to expect schema:DigitalDocuments to be specialisations of schema:Things, but it's unfair to expect them to know that oa:Annotations are schema:Things without the additional prompt.

As to how to render this in json-ld, my first instinct would be to append the type and any additionalTypes of any given node into the "@type" field of the json-ld output - always producing a list, even if it's a list of one item. Unless you foresee a case where we have to retain the separation of "type" and "additionalType" in the JSON-LD, in which case we could directly incorporate the schema:additionalType property into the JSON-LD output. I suspect the former would produce more useful data.

[alastair]

Thanks for the explanation. This distinction is clear to me now.
It'd be nice to make this happen automatically when we create an Annotation using the APi.
@ChristiaanScheermeijer, do you know if it's possible to add some additional logic only to CreateAnnotation so that we automatically fill in a field if it's not provided by the user?

[alastair]

related: #85

[alastair]

I made annotations schema:Things in #100