Return API v2 responses in Turtle and RDF/XML

[benjamingeer]

This PR allows all API v2 responses to be returned in Turtle and RDF/XML as well as in JSON-LD, using HTTP content negotation.

• Change ontology response format to return a single ontology (using @graph in JSON-LD) as per hasClasses and hasProperties produce nonsensical Turtle #854 (requires change in SALSAH 2).
• Change resource response format to use @graph in JSON-LD as per hasClasses and hasProperties produce nonsensical Turtle #854 (requires change in SALSAH 2).
• Serve all Knora API v2 responses in other formats:
  • Turtle
  • RDF/XML
• Specify literal datatypes where necessary in resource responses in the simple schema.
• Use short, human-readable prefix labels when possible.
• Add tests.
  • Test serving ontologies in:
    • Turtle
    • RDF/XML
  • Test serving resources in:
    • Turtle
    • RDF/XML
  • Test serving lists in:
    • Turtle
    • RDF/XML
• Update docs.
  • Docs on querying/editing ontologies.
  • Docs on querying resources.
  • TypeScript definitions and sample responses.
• Update release notes.

I was going to support returning API responses as HTML, but it would be a lot of work, and it doesn't seem worth it, since that's already being done in SALSAH 2.

The conversion from JSON-LD to other formats is done by writing the JSON-LD to a string, then parsing and reformatting it using RDF4J Rio (in RouteUtilV2.formatResponse). I tried converting our JSON-LD data structure directly to a Rio model, but the code to do this turned out to be rather complex, so I decided not to. And a test with ab shows that, even with the extra formatting and parsing, there is no noticeable difference in performance between formats.

The necessary changes to SALSAH 2 are in dhlab-basel/Salsah#252.

Resolves #609.
Resolves #854.
Resolves #857.
Resolves #855.
Resolves #853.
Resolves #863.
Resolves #865.

[benjamingeer]

Example of a book resource in the simple schema in Turtle, with a knora-api:Date datatype:

@prefix knora-api: <http://api.knora.org/ontology/knora-api/simple/v2#> .
@prefix incunabula: <http://0.0.0.0:3333/ontology/0803/incunabula/simple/v2#> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .

<http://rdfh.ch/2a6221216701> a incunabula:book;
  incunabula:book_comment "Katalogaufnahme anhand ISTC und v.d.Haegen";
  incunabula:citation "Borm 1751", "C 3833", "FairMur(G) 283", "Goff M165", "IBP 3556",
    "Klebs 651.2", "Schr 4799", "Schramm XXI p. 9 & 26", "Van der Haegen I: 9,14";
  incunabula:location "Basel UB, Sign: Aleph D III 13:1";
  incunabula:note "Besitzervermerke: Kartause, H. Zscheckenbürlin", "Holzschnitte nicht koloriert",
    "Rubr. mit Init. J zu Beginn", "Zusammengebunden mit: Die zehen Gebote ; Was und wie man beten soll und Auslegung des hlg. Pater nosters / Hans von Warmont. Strassburg, 1516",
    "deutsch von Otto von Diemeringen";
  incunabula:physical_desc "Extent: 1 Bd.; Dimensions: f°";
  incunabula:pubdate "JULIAN:1481 CE"^^knora-api:Date;
  incunabula:publisher "Bernhard Richel";
  incunabula:publoc "Basel";
  incunabula:title "Itinerarius", "Reise ins Heilige Land", "Reysen und wanderschafften durch das Gelobte Land";
  incunabula:url "http://aleph.unibas.ch/F/?local_base=DSV01&con_lng=GER&func=find-b&find_code=SYS&request=002610320";
  rdfs:label "Reise ins Heilige Land" .

[tobiasschweizer]

@benjamingeer I managed to create the test data, but now some tests have to be fixed. I cannot do it before Wednesday. Could you have a look at it? I think it is just the tests that search for things that now have a different result since I added another thing.

[tobiasschweizer]

@benjamingeer I fixed a general problem with the test function in PR #862 but I think some of those should be applied immediately:

webapi/src/test/scala/org/knora/webapi/e2e/v2/ResponseCheckerR2RV2.scala: two additional asserts

webapi/src/test/scala/org/knora/webapi/responders/v2/ResourcesResponseCheckerV2.scala three additional asserts

Shall I add them to this PR?

[benjamingeer]

Yes please.

[tobiasschweizer]

done in 6274fb8

this is just what is absolutely needed, more will come with my PR

[tobiasschweizer]

or probably I decide to make an own PR just for that to be faster