Move Fuseki integration to a Jena module

docs/docs/getting-started-plugins.md

@@ -20,13 +20,9 @@ You can simply add Jelly format support to [Apache Jena](https://jena.apache.org
     - For other applications, consult the manual of the application.
 - You can now use the Jelly format for parsing, serialization, and streaming serialization in your Jena application.
 
-!!! bug "Content negotiation in Fuseki"
+!!! warning "Content negotiation in Fuseki"
 
-    Content negotiation using the `application/x-jelly-rdf` media type in the `Accept` header works in Fuseki "Main" distribution since version 5.2.0. To get it working, you need to run Fuseki with the `--modules=true` command-line option. Content negotiation does not work in the "webapp" distribution with UI due to an [upstream bug](https://github.com/apache/jena/issues/2774).
-
-    In Fuseki 5.1.0 and older, content negotiation with Jelly does not work at all.
-
-    To work around these issues, you can specify the `output=application/x-jelly-rdf` parameter (either in the URL or in the URL-encoded form body) when querying the endpoint.
+    Content negotiation using the `application/x-jelly-rdf` media type in the `Accept` header works in Fuseki since Apache Jena version 5.2.0. Previous versions of Fuseki did not support media type registration.
 
 
 ### Eclipse RDF4J

jena/src/main/resources/META-INF/services/org.apache.jena.sys.JenaSubsystemLifecycle

@@ -1 +1,2 @@
 eu.ostrzyciel.jelly.convert.jena.riot.JellySubsystemLifecycle
+eu.ostrzyciel.jelly.convert.jena.fuseki.JellyFusekiLifecycle

jena/src/main/scala/eu/ostrzyciel/jelly/convert/jena/fuseki/JellyFusekiModule.scala → jena/src/main/scala/eu/ostrzyciel/jelly/convert/jena/fuseki/JellyFusekiLifecycle.scala

@@ -3,45 +3,46 @@ package eu.ostrzyciel.jelly.convert.jena.fuseki
 import eu.ostrzyciel.jelly.core.Constants
 import org.apache.jena.atlas.web.{AcceptList, MediaRange}
 import org.apache.jena.fuseki.{DEF, Fuseki}
-import org.apache.jena.fuseki.main.FusekiServer
-import org.apache.jena.fuseki.main.sys.FusekiAutoModule
-import org.apache.jena.rdf.model.Model
-import org.apache.jena.riot.WebContent
+import org.apache.jena.sys.JenaSubsystemLifecycle
 
 import java.util
 
-object JellyFusekiModule:
+object JellyFusekiLifecycle:
   val mediaRangeJelly: MediaRange = new MediaRange(Constants.jellyContentType)
 
 /**
- * A Fuseki module that adds Jelly content type to the list of accepted content types.
+ * A Jena module that adds Jelly content type to the list of accepted content types in Fuseki.
+ * This isn't a Fuseki module, because Fuseki modules are not supported in all distributions of Fuseki, see:
+ * https://github.com/apache/jena/issues/2774
  *
  * This allows users to use the Accept header set to application/x-jelly-rdf to request Jelly RDF responses.
  * It works for SPARQL CONSTRUCT queries and for the Graph Store Protocol.
- *
- * More info on Fuseki modules: https://jena.apache.org/documentation/fuseki2/fuseki-modules.html
  */
-final class JellyFusekiModule extends FusekiAutoModule:
-  import JellyFusekiModule.*
-
-  override def name(): String = "Jelly"
+final class JellyFusekiLifecycle extends JenaSubsystemLifecycle:
+  import JellyFusekiLifecycle.*
 
   override def start(): Unit =
     try {
       maybeAddJellyToList(DEF.constructOffer).foreach(offer => DEF.constructOffer = offer)
       maybeAddJellyToList(DEF.rdfOffer).foreach(offer => DEF.rdfOffer = offer)
       maybeAddJellyToList(DEF.quadsOffer).foreach(offer => {
         DEF.quadsOffer = offer
-        Fuseki.serverLog.info(s"Added ${Constants.jellyContentType} to the list of accepted content types")
+        Fuseki.serverLog.info(s"Jelly: Added ${Constants.jellyContentType} to the list of accepted content types")
       })
     } catch {
+      case e: NoClassDefFoundError => // ignore, we are not running Fuseki
       case e: IllegalAccessError => Fuseki.serverLog.warn(
-        s"Cannot register the ${Constants.jellyContentType} content type, because you are running an Apache Jena " +
-          s"Fuseki version that doesn't support content type registration. " +
+        s"Jelly: Cannot register the ${Constants.jellyContentType} content type, because you are running an " +
+          s"Apache Jena Fuseki version that doesn't support content type registration. " +
           s"Update to Fuseki 5.2.0 or newer for this to work."
       )
     }
 
+  override def stop(): Unit = ()
+
+  // Initialize after JellySubsystemLifecycle
+  override def level(): Int = 502
+
   /**
    * Adds the Jelly content type to the list of accepted content types if it is not already present.
    * @param list current list of accepted content types

jena/src/test/scala/eu/ostrzyciel/jelly/convert/jena/fuseki/JellyFusekiLifecycleSpec.scala

@@ -0,0 +1,53 @@
+package eu.ostrzyciel.jelly.convert.jena.fuseki
+
+import eu.ostrzyciel.jelly.convert.jena.riot.JellySubsystemLifecycle
+import org.apache.jena.fuseki.DEF
+import org.apache.jena.sys.JenaSystem
+import org.scalatest.matchers.should.Matchers
+import org.scalatest.wordspec.AnyWordSpec
+
+import scala.jdk.CollectionConverters.*
+
+class JellyFusekiLifecycleSpec extends AnyWordSpec, Matchers:
+  "JellyFusekiLifecycle" should {
+    "initialize after JenaSubsystemLifecycle" in {
+      val jenaModule = JellySubsystemLifecycle()
+      val module = JellyFusekiLifecycle()
+      module.level() should be > jenaModule.level()
+    }
+
+    "use the correct content type for Jelly" in {
+      JellyFusekiLifecycle.mediaRangeJelly.getContentTypeStr should be ("application/x-jelly-rdf")
+    }
+
+    "register the Jelly content type in the lists of accepted content types" in {
+      // This assumption is broken for `jenaPlugin` tests, because there the JenaSystem is initialized
+      // and reads the service definition.
+      // This test thus only can be executed in the `jena` module.
+      assume(DEF.constructOffer == DEF.constructOfferDefault())
+
+      val oldLists = List(DEF.constructOffer, DEF.rdfOffer, DEF.quadsOffer)
+      for list <- oldLists do
+        list.entries().asScala should not contain JellyFusekiLifecycle.mediaRangeJelly
+
+      val module = JellyFusekiLifecycle()
+      module.start()
+
+      val lists = List(DEF.constructOffer, DEF.rdfOffer, DEF.quadsOffer)
+      for (list, oldList) <- lists.zip(oldLists) do
+        list.entries().asScala should contain (JellyFusekiLifecycle.mediaRangeJelly)
+        list.entries().size() should be (oldList.entries().size() + 1)
+    }
+
+    "not register the Jelly content type if it's already registered" in {
+      val module = JellyFusekiLifecycle()
+      module.start()
+      DEF.rdfOffer.entries().asScala should contain (JellyFusekiLifecycle.mediaRangeJelly)
+      val size1 = DEF.rdfOffer.entries().size()
+
+      module.start()
+      DEF.rdfOffer.entries().asScala should contain (JellyFusekiLifecycle.mediaRangeJelly)
+      val size2 = DEF.rdfOffer.entries().size()
+      size2 should be (size1)
+    }
+  }