SPARQL Describer

src/main/java/com/mackervoy/calum/mud/MUDApplication.java

@@ -92,6 +92,31 @@ protected static void initSettlement() {
 		}
 	}
 
+	/**
+	 * A temporary function for initialising a demo content graph on startup
+	 */
+	protected static void initDemoContent() {
+		Dataset dataset = TDB2Factory.connectDataset(TDBStore.CONTENT.getFileLocation()) ;
+		try {
+			dataset.begin(ReadWrite.WRITE) ;
+
+			if(!dataset.isEmpty()) {
+		    	dataset.abort();
+		    	return;
+		    }
+
+			Model model = dataset.getDefaultModel();
+
+			//TODO: configure from web.xml
+			model.read("https://calum.inrupt.net/public/collections/content.ttl");
+
+			model.commit();
+		}
+		finally {
+			dataset.end();
+		}
+	}
+
 	/**
 	 * init a TDB server storing world from configuration in Assembler
 	 * https://jena.apache.org/documentation/tdb/java_api.html
@@ -112,6 +137,7 @@ public static void initWorld() {
 	 */
 	public static void registerDescribers() {
 		new StadiumDescriber();
+		new SPARQLDescriber();
 	}
 
 	public static void registerActors() {
@@ -127,6 +153,7 @@ public MUDApplication(@Context ServletContext context) {
 		if(!SITE_URL.endsWith("/")) SITE_URL += "/";
 
 		MUDApplication.initWorld();
+		MUDApplication.initDemoContent();
 		MUDApplication.registerDescribers();
 		MUDApplication.registerActors();
 	}

src/main/java/com/mackervoy/calum/mud/TDBStore.java

@@ -17,6 +17,7 @@
  */
 public class TDBStore {
 	public final static DatasetCollection WORLD = new DatasetCollection("world/");
+	public final static DatasetCollection CONTENT = new DatasetCollection("content/");
 	public final static DatasetCollection ACTIONS = new DatasetCollection("actions/");
 	public final static DatasetCollection TASK_ACTIONS = new DatasetCollection("actions/tasks/");
 

src/main/java/com/mackervoy/calum/mud/content/ContentController.java

@@ -40,9 +40,7 @@ public Response post(String requestBody) {
 			Model m = ModelFactory.createDefaultModel();
 			m.read(res.getURI());
 			final Resource r = m.getResource(res.getURI());
-			System.out.println(r);
 
-			//TODO: technically this should infer any subtype of foaf:Agent
 			ResIterator agents = request.listResourcesWithProperty(RDF.type, MUDCharacter.Character);
 
 			while(agents.hasNext()) {
@@ -62,7 +60,6 @@ private Optional<IContentDescriber> getDescriber(Resource r) {
 		// check if I have a describer for the URI
 		DescriberFactory factory = new DescriberFactory();
 		IContentDescriber describer = factory.getDescriber(r.getURI());
-		System.out.println("found " + describer + " from " + r.getURI());
 
 		// if I don't, try the RDF type
 		if (describer == null) {
@@ -74,6 +71,8 @@ private Optional<IContentDescriber> getDescriber(Resource r) {
 				describer = null;
 			}
 		}
+
+		System.out.println("found " + describer + " from " + r.getURI());
 
 		return Optional.ofNullable(describer);
   }

src/main/java/com/mackervoy/calum/mud/content/SPARQLDescriber.java

@@ -0,0 +1,72 @@
+package com.mackervoy.calum.mud.content;
+
+import java.util.Optional;
+
+import javax.ws.rs.NotFoundException;
+
+import org.apache.jena.rdf.model.Model;
+import org.apache.jena.rdf.model.ModelFactory;
+import org.apache.jena.rdf.model.Property;
+import org.apache.jena.rdf.model.Resource;
+import org.apache.jena.query.*;
+
+import com.mackervoy.calum.mud.DatasetItem;
+import com.mackervoy.calum.mud.TDBStore;
+import com.mackervoy.calum.mud.vocabularies.MUDCharacter;
+import com.mackervoy.calum.mud.vocabularies.MUDContent;
+
+public class SPARQLDescriber extends AbstractDescriber {
+
+	//TODO: this class will be a generic describer for completing a SPARQL lookup
+	public SPARQLDescriber() {
+		this.addTargetRDFType(MUDCharacter.Character.toString());
+	}
+
+	/**
+	 * @return A DatasetItem where the graph of content in the TDBStore is stored, or None
+	 */
+	protected Optional<DatasetItem> getContentDatasetItem() {
+		try {
+			return Optional.of(TDBStore.getDatasetItem(TDBStore.CONTENT.getFileLocation()));
+		}
+		catch(NotFoundException e) {
+			return Optional.empty();
+		}
+	}
+
+	protected Optional<Model> getContentDescribingObject(DatasetItem contentDataset, Resource agent, Resource r) {
+		// Select all triples where the subject describes a character
+		// TODO: prioritise those triples which target *this character*
+		String queryString = "SELECT ?s WHERE { ?s <" + MUDContent.describes.toString() + "> <" + MUDCharacter.Character.toString() + "> }";
+		Query query = QueryFactory.create(queryString);
+
+		Model result = ModelFactory.createDefaultModel();
+		Model contentGraph = contentDataset.getModel();
+
+		try (QueryExecution qexec = QueryExecutionFactory.create(query, contentGraph)) {
+		    ResultSet results = qexec.execSelect();
+
+		    while(results.hasNext()) {
+		    	Resource subject = results.nextSolution().getResource("s");
+
+		    	// read the full subject into the result graph
+		    	// TODO: this could probably be more efficient
+		    	Model content = ModelFactory.createDefaultModel().read(subject.getURI());
+
+		    	// construct the appropriate sense from the content model
+		    	Resource sense = subject.getPropertyResourceValue(MUDContent.usesSense);
+		    	Property usesSense = sense == null ? MUDContent.sees : MUDContent.SENSE_TO_PROPERTY.get(sense);
+
+		    	result.add(agent, usesSense, subject);
+		    	result.add(content);
+		    }
+		}
+
+		return result.isEmpty() ? Optional.empty() : Optional.of(result);
+	}
+
+	public Optional<Model> describe(Resource agent, Resource r) {
+		return this.getContentDatasetItem()
+				.flatMap(datasetItem -> this.getContentDescribingObject(datasetItem, agent, r));
+	}
+}

src/main/java/com/mackervoy/calum/mud/vocabularies/MUDContent.java

@@ -1,5 +1,9 @@
 package com.mackervoy.calum.mud.vocabularies;
 
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
 import org.apache.jena.rdf.model.* ;
 
 /*
@@ -23,8 +27,19 @@ protected static final Property property( String local )
     { return ResourceFactory.createProperty( uri, local ); }
 
     public final static Resource Content = resource( "Content" );
+    public final static Resource Sense = resource("Sense");
+    public final static Resource Sight = resource("Sight");
+    public final static Property usesSense = property("usesSense");
     public final static Property sees = property("sees");
     public final static Property describes = property("describes");
     public final static Property hasText = property("hasText");
     public final static Property hasImage = property("hasImage");
+
+    //Map of Sense classes to their property values
+    public static final Map<Resource, Property> SENSE_TO_PROPERTY;
+    static {
+        Map<Resource, Property> internalMap = new HashMap<Resource,Property>();
+        internalMap.put(Sight, sees);
+        SENSE_TO_PROPERTY = Collections.unmodifiableMap(internalMap);
+    }
 }