Return API v2 responses in Turtle and RDF/XML (#851)

* feature (webapi): Start implementing HTTP content negotation in API v2.

* fix (docs): Fix docs build error on Travis.

* feature (webapi): Add support for returning API v2 responses in Turtle.

* fix (webapi): Fix deployment issues #853, #855.

* fix (webapi): Use UTF-8 to read file resources.

* feature (webapi): Use @graph instead of hasOntologies, etc. (ongoing)

* feature (webapi): Replace hasOntologies with JSON-LD graph.

* test (webapi): Add tests for serving ontologies in Turtle.

* refactor (webapi): Refactor handling of RDF media types.

- Use JSON-LD content type for JSON-LD responses.

* feature (webapi): Return ontology responses in RDF/XML.

- Simplify R2R ontology test code.
- Make it easier to regenerate expected response files.

* feature (webapi): Don't bother trying to return HTML.

* refactor (webapi): Move some methods into JsonLDObject.

* feature (webapi): Change resource responses to use JSON-LD graphs.

* feature (webapi): Return resources in Turtle and RDF/XML.

- Add datatypes where needed in responses in the simple schema.

* docs (webapi): Update docs and release notes.

* feature (webapi): Use simple prefix labels in responses when possible.

* docs (knora-ontologies): Fix mistakes in salsah-gui doc.

* tests (add test data)

* test (webapi): Update tests to reflect new test data.

* feature (webapi): Support q values in content negotiation.

- Rename RouteUtilV2.runJsonRoute -> runRdfRoute.

* fix (webapi): Store project shortcodes in upper case (#865).

* fix (webapi): Don't treat application/xml as an RDF media type, to avoid returning it to browsers.

* style (webapi): Fix typos.

* refactor (webapi): Remove unnecessary method type parameter.

* style (webapi): Improve comments.

* refactor (webapi): Remove unnecessary pattern match.

* test (webapi): Update tests.

- Add tests for requesting lists in Turtle and RDF/XML.
- Update sample resource responses in resourcesResponses.ts.

* fix (fix test functions)

* test (webapi): Try increasing timeout to prevent Travis test failures.

* fix (webapi): Trim whitespace from elements of Accept header.

* fix (webapi): Fix exception.

docs/src/api-v2/MappingFormats.ts

@@ -65,4 +65,3 @@ export module MappingFormats {
 
 
 }
-

docs/src/api-v2/ResourcesResponse.ts

@@ -71,21 +71,10 @@ export module ResourcesResponse {
          *
          */
         export interface ResourcesSequence {
-            /**
-             * ResourcesSequence response format corresponds to http://schema.org/ItemList
-             */
-            "@type": "http://schema.org/ItemList";
-
             /**
              * A resource or a sequence of resources (instances).
              */
-            "http://schema.org/itemListElement": Resource | Array<Resource>;
-
-            /**
-             * Length of the sequence of resources.
-             */
-            "http://schema.org/numberOfItems": number;
-
+            "@graph": Array<Resource>;
         }
     }
 
@@ -127,23 +116,13 @@ export module ResourcesResponse {
          *
          */
         export interface ResourcesSequence {
-            /**
-             * ResourcesSequence response format corresponds to http://schema.org/ItemList
-             */
-            "@type": "http://schema.org/ItemList";
-
             /**
              * A resource or a sequence of resources (instances).
              */
-            "http://schema.org/itemListElement": Resource | Array<Resource>;
-
-            /**
-             * Length of the sequence of resources.
-             */
-            "http://schema.org/numberOfItems": number;
+            "@graph": Array<Resource>;
 
         }
 
     }
 
-}
+}

docs/src/paradox/00-release-notes/v1.5.0.md

@@ -13,6 +13,7 @@ New features:
 
 - Resources can be returned in the simple ontology schema (#833).
 - Text values can specify the language of the text (#819).
+- Responses can be returned in Turtle and RDF/XML (#851).
 
 Bugfixes:
 ---------

docs/src/paradox/02-knora-ontologies/salsah-gui.md

@@ -74,9 +74,8 @@ The attributes used with each GUI element are described below under
 `guiAttributeDefinition`
 
 :   Used only in the `salsah-gui` ontology itself, as a predicate
-    attached to instances of `Guielement` (see
-    [salsah-gui-individuals]{role="ref"}), to specify the attributes
-    that can be given as objects of `guiAttribute` when a given
+    attached to instances of `Guielement` (see @ref:[Individuals](#individuals)),
+    to specify the attributes that can be given as objects of `guiAttribute` when a given
     `Guielement`. is used. The objects of this predicate are written in
     a DSL with the following syntax:
 
@@ -136,31 +135,31 @@ identifier = letter , { letter } ;
 `List`
 
 :   A GUI element for selecting an item in a hierarchical list (see
-    [knora-base-list-value]{role="ref"}). A property definition that
+    @ref:[ListValue](knora-base.md#listvalue)). A property definition that
     uses this element must also contain this `guiAttribute` predicate:
 
     -   `"hlist=<LIST_IRI>"`, where `LIST_IRI` is the IRI of a
-        `knora-base:ListNode`.
+        `knora-base:ListNode` that is the root node of a hierarchical list.
 
 `Pulldown`
 
 :   A GUI element for selecting an item in a flat list (see
-    [knora-base-list-value]{role="ref"}) using a pull-down menu. A
+    @ref:[ListValue](knora-base.md#listvalue)) using a pull-down menu. A
     property definition that uses this element must also contain this
     `guiAttribute` predicate:
 
     -   `"hlist=<LIST_IRI>"`, where `LIST_IRI` is the IRI of a
-        `knora-base:ListNode`.
+        `knora-base:ListNode` that is the root node of a hierarchical list.
 
 `Radio`
 
 :   A GUI element for selecting an item in a flat list (see
-    [knora-base-list-value]{role="ref"}) using radio buttons. A property
+    @ref:[ListValue](knora-base.md#listvalue)) using radio buttons. A property
     definition that uses this element must also contain this
     `guiAttribute` predicate:
 
     -   `"hlist=<LIST_IRI>"`, where `LIST_IRI` is the IRI of a
-        `knora-base:ListNode`.
+        `knora-base:ListNode` that is the root node of a hierarchical list.
 
 `Richtext`
 

docs/src/paradox/03-webapi/api-v2/index.md

@@ -30,6 +30,5 @@ License along with Knora.  If not, see <http://www.gnu.org/licenses/>.
 - [XML to Standoff Mapping](xml-to-standoff-mapping.md)
 - [KnarQL: Knora Query Language](query-language.md)
 - [Querying, Creating, and Updating Ontologies](ontology-information.md)
-- [Response Formats](response-formats.md)
 
 @@@

docs/src/paradox/03-webapi/api-v2/introduction.md

@@ -17,7 +17,7 @@ You should have received a copy of the GNU Affero General Public
 License along with Knora.  If not, see <http://www.gnu.org/licenses/>.
 -->
 
-# Introduction: Using API V2
+# Introduction: Using API v2
 
 @@toc
 
@@ -32,13 +32,28 @@ format that is consistent and hence easier to use for a client.
 Please note that V2 is still in development. We do not yet recommend
 using it on productive systems.
 
-## V2 Path Segment
+## API v2 Path Segment
 
-Every request to API V1 includes `v2` as a path segment, e.g.
+Every request to API v2 includes `v2` as a path segment, e.g.
 `http://host/v2/resources/http%3A%2F%2Frdfh.ch%2Fc5058f3a`.
 Accordingly, requests using any other version of the API will require
 another path segment.
 
+## Response Formats
+
+All API v2 responses can be returned in
+[JSON-LD](https://json-ld.org/spec/latest/json-ld/),
+[Turtle](https://www.w3.org/TR/turtle/),
+or [RDF/XML](https://www.w3.org/TR/rdf-syntax-grammar/), using
+@extref[HTTP content negotiation](rfc:7231#section-5.3.2). The client
+can request these formats using the following MIME types:
+
+| Format  | MIME Type             |
+|---------|-----------------------|
+| JSON-LD | `application/ld+json` |
+| Turtle  | `text/turtle`         |
+| RDF/XML | `application/rdf+xml` |
+
 ## JSON-LD
 
 Our preferred format for data exchange is
@@ -53,36 +68,22 @@ RDF types (e.g. XSD datatypes) or more complex types whose IRIs can be
 dereferenced to get more information about their structure.
 
 At the same time, JSON-LD responses are relatively easy for software
-developers to work with. Items in a response can have human-readable
-names, which can nevertheless be expanded to full IRIs. Also, while a
-format such as [Turtle](https://www.w3.org/TR/turtle/) just provides a
+developers to work with, and are more concise and easier to read than
+the equivalent XML. Items in a response can have human-readable names,
+which can nevertheless be expanded to full IRIs. Also, while a format such as
+[Turtle](https://www.w3.org/TR/turtle/) just provides a
 set of RDF triples, an equivalent JSON-LD response can explicitly
 provide data in a hierarchical structure, with objects nested inside
 other objects.
 
-We designed the V2 routes in a way that would also allow for the usage
-of other formats such as XML. We plan to implement support for XML once
-the implementation of JSON-LD is completed. The client will be able to
-use content negotiation to specify the preferred exchange format.
-
-## Support of schema.org Entities
-
-Some entities defined in [schema.org](http://www.schema.org) are used in
-API v2 responses (e.g., `ResourcesSequence`, see
-@ref:[Response Formats](response-formats.md)). For example,
-`knora-api:Resource` is declared to be a subclass of
-`http://schema.org/Thing`, so we can use a `knora-api:Resource` or
-any of its subclasses where `http://schema.org` requires a
-`http://schema.org/Thing`.
-
 ## Knora IRIs
 
 Resources and entities are identified by IRIs. The format of these IRIs
 is explained in @ref:[Knora IRIs](knora-iris.md).
 
 ## API Schema
 
-Knora API V2 offers the query and response format in a complex schema
+Knora API v2 offers the query and response format in a complex schema
 and a simple one. The main difference is that the complex schema exposes
 the complexity of value objects, while the simple version does not. A
 client that needs to edit values must use the complex schema in order to