Faster implementation of TPF for SDB (#54)

* Initial performance improvements to TPF

* Add faster counts for TPF

* Correct end count

* Bug fixes, use hashes for filtering

* Initial LDF SPARQL client

* Handle blank nodes correctly

api/src/main/java/edu/cornell/mannlib/vitro/webapp/rdfservice/RDFService.java

@@ -8,6 +8,7 @@ import java.util.List;
 
 import org.apache.jena.rdf.model.Model;
 import org.apache.jena.rdf.model.ModelChangedListener;
+import org.apache.jena.rdf.model.RDFNode;
 
 /**
  * Interface for API to write, read, and update Vitro's RDF store, with support 
@@ -249,6 +250,10 @@ public interface RDFService {
 	 */
 	public ChangeSet manufactureChangeSet();
 
+	public long countTriples(RDFNode subject, RDFNode predicate, RDFNode object) throws RDFServiceException;
+
+	public Model getTriples(RDFNode subject, RDFNode predicate, RDFNode object, long limit, long offset) throws RDFServiceException;
+		
 	/**
      * Frees any resources held by this RDFService object
      * 

api/src/main/java/edu/cornell/mannlib/vitro/webapp/rdfservice/filter/LanguageFilteringRDFService.java

@@ -468,6 +468,16 @@ public class LanguageFilteringRDFService implements RDFService {
         return s.manufactureChangeSet();
     }
 
+    @Override
+    public long countTriples(RDFNode subject, RDFNode predicate, RDFNode object) throws RDFServiceException {
+        return s.countTriples(subject, predicate, object);
+    }
+
+    @Override
+    public Model getTriples(RDFNode subject, RDFNode predicate, RDFNode object, long limit, long offset) throws RDFServiceException {
+        return s.getTriples(subject, predicate, object, limit, offset);
+    }
+
     @Override
     public void close() {
         s.close();            

api/src/main/java/edu/cornell/mannlib/vitro/webapp/rdfservice/impl/RDFServiceFactorySingle.java

@@ -16,6 +16,7 @@ import edu.cornell.mannlib.vitro.webapp.rdfservice.RDFServiceException;
 import edu.cornell.mannlib.vitro.webapp.rdfservice.RDFServiceFactory;
 import edu.cornell.mannlib.vitro.webapp.rdfservice.ResultSetConsumer;
 import edu.cornell.mannlib.vitro.webapp.utils.logging.ToString;
+import org.apache.jena.rdf.model.RDFNode;
 
 /**
  * An RDFServiceFactory that always returns the same RDFService object
@@ -192,6 +193,16 @@ public class RDFServiceFactorySingle implements RDFServiceFactory {
             return s.manufactureChangeSet();
         }
 
+        @Override
+        public long countTriples(RDFNode subject, RDFNode predicate, RDFNode object) throws RDFServiceException {
+            return s.countTriples(subject, predicate, object);
+        }
+
+        @Override
+        public Model getTriples(RDFNode subject, RDFNode predicate, RDFNode object, long limit, long offset) throws RDFServiceException {
+            return s.getTriples(subject, predicate, object, limit, offset);
+        }
+
         @Override
         public void close() {
             // Don't close s.  It's being used by everybody.

api/src/main/java/edu/cornell/mannlib/vitro/webapp/rdfservice/impl/RDFServiceImpl.java

@@ -12,18 +12,24 @@ import java.util.concurrent.CopyOnWriteArrayList;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
+import org.apache.jena.atlas.io.StringWriterI;
 import org.apache.jena.graph.Node;
 import org.apache.jena.graph.NodeFactory;
 import org.apache.jena.graph.Triple;
 import org.apache.jena.query.Query;
 import org.apache.jena.query.QueryFactory;
 import org.apache.jena.query.QueryParseException;
+import org.apache.jena.query.QuerySolution;
 import org.apache.jena.query.Syntax;
+import org.apache.jena.rdf.model.Literal;
 import org.apache.jena.rdf.model.Model;
 import org.apache.jena.rdf.model.ModelChangedListener;
 import org.apache.jena.rdf.model.ModelFactory;
+import org.apache.jena.rdf.model.RDFNode;
 import org.apache.jena.rdf.model.Statement;
 import org.apache.jena.rdf.model.StmtIterator;
+import org.apache.jena.riot.out.NodeFormatter;
+import org.apache.jena.riot.out.NodeFormatterTTL;
 import org.apache.jena.vocabulary.RDF;
 
 import edu.cornell.mannlib.vitro.webapp.rdfservice.ChangeListener;
@@ -34,6 +40,7 @@ import edu.cornell.mannlib.vitro.webapp.rdfservice.RDFService;
 import edu.cornell.mannlib.vitro.webapp.rdfservice.RDFServiceException;
 import edu.cornell.mannlib.vitro.webapp.rdfservice.ResultSetConsumer;
 import edu.cornell.mannlib.vitro.webapp.utils.logging.ToString;
+import org.vivoweb.linkeddatafragments.datasource.rdfservice.RDFServiceBasedRequestProcessorForTPFs;
 
 public abstract class RDFServiceImpl implements RDFService {
 	
@@ -341,4 +348,120 @@ public abstract class RDFServiceImpl implements RDFService {
 		return ToString.simpleName(this) + "[" + ToString.hashHex(this) + "]";
 	}
 
+    @Override
+    public long countTriples(RDFNode subject, RDFNode predicate, RDFNode object) throws RDFServiceException {
+        StringBuilder whereClause = new StringBuilder();
+        StringBuilder orderBy = new StringBuilder();
+
+        if ( subject != null ) {
+            appendNode(whereClause.append(' '), subject);
+        } else {
+            whereClause.append(" ?s");
+            orderBy.append(" ?s");
+        }
+
+        if ( predicate != null ) {
+            appendNode(whereClause.append(' '), predicate);
+        } else {
+            whereClause.append(" ?p");
+            orderBy.append(" ?p");
+        }
+
+        if ( object != null ) {
+            appendNode(whereClause.append(' '), object);
+        } else {
+            whereClause.append(" ?o");
+            orderBy.append(" ?o");
+        }
+
+        long estimate = -1;
+
+        StringBuilder count = new StringBuilder();
+        count.append("SELECT (COUNT(*) AS ?count) WHERE { ");
+        count.append(whereClause.toString());
+        count.append(" . ");
+        count.append(" }");
+        CountConsumer countConsumer = new CountConsumer();
+        this.sparqlSelectQuery(count.toString(), countConsumer);
+        return countConsumer.count;
+    }
+
+    @Override
+    public Model getTriples(RDFNode subject, RDFNode predicate, RDFNode object, long limit, long offset) throws RDFServiceException {
+        StringBuilder whereClause = new StringBuilder();
+        StringBuilder orderBy = new StringBuilder();
+
+        if ( subject != null ) {
+            appendNode(whereClause.append(' '), subject);
+        } else {
+            whereClause.append(" ?s");
+            orderBy.append(" ?s");
+        }
+
+        if ( predicate != null ) {
+            appendNode(whereClause.append(' '), predicate);
+        } else {
+            whereClause.append(" ?p");
+            orderBy.append(" ?p");
+        }
+
+        if ( object != null ) {
+            appendNode(whereClause.append(' '), object);
+        } else {
+            whereClause.append(" ?o");
+            orderBy.append(" ?o");
+        }
+
+        StringBuilder constructQuery = new StringBuilder();
+
+        constructQuery.append("CONSTRUCT { ");
+        constructQuery.append(whereClause.toString());
+        constructQuery.append(" } WHERE { ");
+        constructQuery.append(whereClause.toString()).append(" . ");
+        constructQuery.append(" }");
+
+        if (orderBy.length() > 0) {
+            constructQuery.append(" ORDER BY").append(orderBy.toString());
+        }
+
+        if (limit > 0) {
+            constructQuery.append(" LIMIT ").append(limit);
+        }
+
+        if (offset > 0) {
+            constructQuery.append(" OFFSET ").append(offset);
+        }
+
+        Model triples = ModelFactory.createDefaultModel();
+        this.sparqlConstructQuery(constructQuery.toString(), triples);
+
+        return triples;
+    }
+
+    private void appendNode(StringBuilder builder, RDFNode node) {
+        if (node.isLiteral()) {
+            builder.append(literalToString(node.asLiteral()));
+        } else if (node.isURIResource()) {
+            builder.append('<' + node.asResource().getURI() + '>');
+        }
+    }
+
+    private String literalToString(Literal l) {
+        StringWriterI sw = new StringWriterI();
+        NodeFormatter fmt = new NodeFormatterTTL(null, null);
+        fmt.formatLiteral(sw, l.asNode());
+        return sw.toString();
+    }
+
+    class CountConsumer extends ResultSetConsumer {
+        public long count = -1;
+
+        @Override
+        protected void processQuerySolution(QuerySolution qs) {
+            if (count == -1) {
+                Literal literal = qs.getLiteral("count");
+                count = literal.getLong();
+            }
+        }
+    }
 }

api/src/main/java/edu/cornell/mannlib/vitro/webapp/rdfservice/impl/jena/RDFServiceJena.java

@@ -16,6 +16,9 @@ import edu.cornell.mannlib.vitro.webapp.rdfservice.ResultSetConsumer;
 import org.apache.commons.io.IOUtils;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.apache.jena.query.QuerySolutionMap;
+import org.apache.jena.query.Syntax;
+import org.apache.jena.rdf.model.Literal;
 import org.apache.jena.riot.RDFDataMgr;
 import org.apache.log4j.lf5.util.StreamUtils;
 
@@ -612,6 +615,71 @@ public abstract class RDFServiceJena extends RDFServiceImpl implements RDFServic
         return graph.isIsomorphicWith(fromTripleStoreModel);
     }
 
+    @Override
+    public long countTriples(RDFNode subject, RDFNode predicate, RDFNode object) throws RDFServiceException {
+        Query countQuery = QueryFactory.create("SELECT (COUNT(?s) AS ?count) WHERE { ?s ?p ?o } ORDER BY ?s ?p ?o", Syntax.syntaxSPARQL_11);
+        QuerySolutionMap map = new QuerySolutionMap();
+        if ( subject != null ) {
+            map.add("s", subject);
+        }
+        if ( predicate != null ) {
+            map.add("p", predicate);
+        }
+        if ( object != null ) {
+            map.add("o", object);
+        }
+
+        DatasetWrapper dw = getDatasetWrapper();
+        try {
+            Dataset d = dw.getDataset();
+            try (QueryExecution qexec = QueryExecutionFactory.create(countQuery, d, map)) {
+                ResultSet results = qexec.execSelect();
+                if (results.hasNext()) {
+                    QuerySolution soln = results.nextSolution() ;
+                    Literal literal = soln.getLiteral("count");
+                    return literal.getLong();
+                }
+            }
+        } finally {
+            dw.close();
+        }
+
+        return 0;
+    }
+
+    @Override
+    public Model getTriples(RDFNode subject, RDFNode predicate, RDFNode object, long limit, long offset) throws RDFServiceException {
+        Query query = QueryFactory.create("CONSTRUCT WHERE { ?s ?p ?o }", Syntax.syntaxSPARQL_11);
+        QuerySolutionMap map = new QuerySolutionMap();
+        if ( subject != null ) {
+            map.add("s", subject);
+        }
+        if ( predicate != null ) {
+            map.add("p", predicate);
+        }
+        if ( object != null ) {
+            map.add("o", object);
+        }
+
+        query.setOffset(offset);
+        query.setLimit(limit);
+
+        Model triples = ModelFactory.createDefaultModel();
+
+        DatasetWrapper dw = getDatasetWrapper();
+        try {
+            Dataset d = dw.getDataset();
+            try (QueryExecution qexec = QueryExecutionFactory.create(query, d, map)) {
+                qexec.execConstruct(triples);
+            }
+
+            return triples;
+        } finally {
+            dw.close();
+        }
+    }
+
+
     @Override
     public void close() {
         // nothing
@@ -620,5 +688,4 @@ public abstract class RDFServiceJena extends RDFServiceImpl implements RDFServic
     protected QueryExecution createQueryExecution(String queryString, Query q, Dataset d) {
         return QueryExecutionFactory.create(q, d);
     }
-    
 }

api/src/main/java/edu/cornell/mannlib/vitro/webapp/rdfservice/impl/jena/sdb/RDFServiceSDB.java

@@ -4,20 +4,34 @@ package edu.cornell.mannlib.vitro.webapp.rdfservice.impl.jena.sdb;
 
 import java.io.IOException;
 import java.sql.Connection;
+import java.sql.ResultSet;
 import java.sql.SQLException;
+import java.sql.Statement;
 
 import javax.sql.DataSource;
 
+import org.apache.commons.lang3.StringUtils;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
+import org.apache.jena.datatypes.RDFDatatype;
+import org.apache.jena.datatypes.TypeMapper;
+import org.apache.jena.datatypes.xsd.XSDDatatype;
+import org.apache.jena.graph.Node;
+import org.apache.jena.graph.NodeFactory;
+import org.apache.jena.graph.Triple;
 import org.apache.jena.query.Dataset;
 import org.apache.jena.query.Query;
 import org.apache.jena.query.QueryExecution;
 import org.apache.jena.query.QueryExecutionFactory;
+import org.apache.jena.rdf.model.Model;
+import org.apache.jena.rdf.model.ModelFactory;
+import org.apache.jena.rdf.model.RDFNode;
 import org.apache.jena.sdb.SDBFactory;
 import org.apache.jena.sdb.Store;
 import org.apache.jena.sdb.StoreDesc;
+import org.apache.jena.sdb.layout2.NodeLayout2;
+import org.apache.jena.sdb.layout2.ValueType;
 import org.apache.jena.sdb.sql.SDBConnection;
 
 import edu.cornell.mannlib.vitro.webapp.dao.jena.DatasetWrapper;
@@ -28,6 +42,8 @@ import edu.cornell.mannlib.vitro.webapp.rdfservice.ChangeSet;
 import edu.cornell.mannlib.vitro.webapp.rdfservice.RDFService;
 import edu.cornell.mannlib.vitro.webapp.rdfservice.RDFServiceException;
 import edu.cornell.mannlib.vitro.webapp.rdfservice.impl.jena.RDFServiceJena;
+import org.apache.jena.sdb.store.DatabaseType;
+import org.apache.jena.sdb.store.LayoutType;
 
 public class RDFServiceSDB extends RDFServiceJena implements RDFService {
 
@@ -148,6 +164,116 @@ public class RDFServiceSDB extends RDFServiceJena implements RDFService {
         // However, in recent Jena this turns out to be much slower than executing against the dataset directly
     }
 
+    @Override
+    public long countTriples(RDFNode subject, RDFNode predicate, RDFNode object) throws RDFServiceException {
+        if (LayoutType.LayoutTripleNodesHash.equals(storeDesc.getLayout())) {
+            if (DatabaseType.MySQL.equals(storeDesc.getDbType()) ||
+                DatabaseType.PostgreSQL.equals(storeDesc.getDbType())) {
+                SDBConnection sdbConn = getSDBConnection();
+                try {
+                    String whereClause = makeWhereClause(subject, predicate, object);
+                    Statement stmt = sdbConn.getSqlConnection().createStatement();
+                    ResultSet rs = stmt.executeQuery("SELECT count(DISTINCT s,p,o) AS tcount FROM Quads" + (StringUtils.isEmpty(whereClause) ? "" : " WHERE " + whereClause));
+                    try {
+                        while (rs.next()) {
+                            return rs.getLong("tcount");
+                        }
+                    } finally {
+                        rs.close();
+                    }
+                } catch (SQLException sqle) {
+                    throw new RDFServiceException("Unable to retrieve triples", sqle);
+                } finally {
+                    close(sdbConn);
+                }
+            }
+        } else {
+            return super.countTriples(subject, predicate, object);
+        }
+
+        return super.countTriples(subject, predicate, object);
+    }
+
+    @Override
+    public Model getTriples(RDFNode subject, RDFNode predicate, RDFNode object, long limit, long offset) throws RDFServiceException {
+        if (LayoutType.LayoutTripleNodesHash.equals(storeDesc.getLayout())) {
+            if (DatabaseType.MySQL.equals(storeDesc.getDbType()) ||
+                DatabaseType.PostgreSQL.equals(storeDesc.getDbType())) {
+                Model triples = ModelFactory.createDefaultModel();
+
+                SDBConnection sdbConn = getSDBConnection();
+                try {
+                    String whereClause = makeWhereClause(subject, predicate, object);
+                    Statement stmt = sdbConn.getSqlConnection().createStatement();
+                    ResultSet rs = stmt.executeQuery("SELECT \n" +
+                            "N1.lex      AS s_lex,\n" +
+                            "N1.lang     AS s_lang,\n" +
+                            "N1.datatype AS s_datatype,\n" +
+                            "N1.type     AS s_type,\n" +
+                            "N2.lex      AS p_lex,\n" +
+                            "N2.lang     AS p_lang,\n" +
+                            "N2.datatype AS p_datatype,\n" +
+                            "N2.type     AS p_type,\n" +
+                            "N3.lex      AS o_lex,\n" +
+                            "N3.lang     AS o_lang,\n" +
+                            "N3.datatype AS o_datatype,\n" +
+                            "N3.type     AS o_type\n" +
+                            "FROM\n" +
+                            "(SELECT DISTINCT s,p,o FROM Quads" +
+                            (StringUtils.isEmpty(whereClause) ? "" : " WHERE " + whereClause) +
+                            " ORDER BY s,p,o " +
+                            (limit > 0 ? "LIMIT " + limit : "") +
+                            (offset > 0 ? " OFFSET " + offset : "") + ") Q\n" +
+                            "LEFT OUTER JOIN\n" +
+                            "\tNodes AS N1\n" +
+                            "ON ( Q.s = N1.hash )\n" +
+                            "LEFT OUTER JOIN\n" +
+                            "\tNodes AS N2\n" +
+                            "ON ( Q.p = N2.hash )\n" +
+                            "LEFT OUTER JOIN\n" +
+                            "\tNodes AS N3\n" +
+                            "ON ( Q.o = N3.hash )");
+
+                    try {
+                        while (rs.next()) {
+                            Node subjectNode = makeNode(
+                                    rs.getString("s_lex"),
+                                    rs.getString("s_datatype"),
+                                    rs.getString("s_lang"),
+                                    ValueType.lookup(rs.getInt("s_type")));
+
+                            Node predicateNode = makeNode(
+                                    rs.getString("p_lex"),
+                                    rs.getString("p_datatype"),
+                                    rs.getString("p_lang"),
+                                    ValueType.lookup(rs.getInt("p_type")));
+
+                            Node objectNode = makeNode(
+                                    rs.getString("o_lex"),
+                                    rs.getString("o_datatype"),
+                                    rs.getString("o_lang"),
+                                    ValueType.lookup(rs.getInt("o_type")));
+
+                            triples.add(
+                                    triples.asStatement(Triple.create(subjectNode, predicateNode, objectNode))
+                            );
+                        }
+                    } finally {
+                        rs.close();
+                    }
+                } catch (SQLException sqle) {
+                    throw new RDFServiceException("Unable to retrieve triples", sqle);
+                } finally {
+                    close(sdbConn);
+                }
+
+                return triples;
+            }
+        }
+
+        return super.getTriples(subject, predicate, object, limit, offset);
+    }
+
     @Override
     public void close() {
         if (conn != null) {
@@ -159,4 +285,55 @@ public class RDFServiceSDB extends RDFServiceJena implements RDFService {
         }
     }
 
+    // Copied from Jena SQLBridge2
+    private static Node makeNode(String lex, String datatype, String lang, ValueType vType) {
+        switch(vType) {
+            case BNODE:
+                return NodeFactory.createBlankNode(lex);
+            case URI:
+                return NodeFactory.createURI(lex);
+            case STRING:
+                return NodeFactory.createLiteral(lex, lang);
+            case XSDSTRING:
+                return NodeFactory.createLiteral(lex, XSDDatatype.XSDstring);
+            case INTEGER:
+                return NodeFactory.createLiteral(lex, XSDDatatype.XSDinteger);
+            case DOUBLE:
+                return NodeFactory.createLiteral(lex, XSDDatatype.XSDdouble);
+            case DATETIME:
+                return NodeFactory.createLiteral(lex, XSDDatatype.XSDdateTime);
+            case OTHER:
+                RDFDatatype dt = TypeMapper.getInstance().getSafeTypeByName(datatype);
+                return NodeFactory.createLiteral(lex, dt);
+            default:
+                log.warn("Unrecognized: (" + lex + ", " + lang + ", " + vType + ")");
+                return NodeFactory.createLiteral("UNRECOGNIZED");
+        }
+    }
+
+    private String makeWhereClause(RDFNode subject, RDFNode predicate, RDFNode object) {
+        StringBuilder whereClause = new StringBuilder();
+        if (subject != null) {
+            if (whereClause.length() > 0) {
+                whereClause.append(" AND ");
+            }
+            whereClause.append("s=").append(NodeLayout2.hash(subject.asNode()));
+        }
+
+        if (predicate != null) {
+            if (whereClause.length() > 0) {
+                whereClause.append(" AND ");
+            }
+            whereClause.append("p=").append(NodeLayout2.hash(predicate.asNode()));
+        }
+
+        if (object != null) {
+            if (whereClause.length() > 0) {
+                whereClause.append(" AND ");
+            }
+            whereClause.append("o=").append(NodeLayout2.hash(object.asNode()));
+        }
+
+        return whereClause.length() > 0 ? whereClause.toString() : null;
+    }
 }

api/src/main/java/edu/cornell/mannlib/vitro/webapp/rdfservice/impl/logging/LoggingRDFService.java

@@ -14,6 +14,7 @@ import edu.cornell.mannlib.vitro.webapp.rdfservice.ChangeSet;
 import edu.cornell.mannlib.vitro.webapp.rdfservice.RDFService;
 import edu.cornell.mannlib.vitro.webapp.rdfservice.RDFServiceException;
 import edu.cornell.mannlib.vitro.webapp.rdfservice.ResultSetConsumer;
+import org.apache.jena.rdf.model.RDFNode;
 
 /**
  * This RDFService wrapper adds instrumentation to the time-consuming methods of
@@ -182,6 +183,16 @@ public class LoggingRDFService implements RDFService {
 		return innerService.manufactureChangeSet();
 	}
 
+	@Override
+	public long countTriples(RDFNode subject, RDFNode predicate, RDFNode object) throws RDFServiceException {
+		return innerService.countTriples(subject, predicate, object);
+	}
+
+	@Override
+	public Model getTriples(RDFNode subject, RDFNode predicate, RDFNode object, long limit, long offset) throws RDFServiceException {
+		return innerService.getTriples(subject, predicate, object, limit, offset);
+	}
+
 	@Override
 	public void close() {
 		innerService.close();

api/src/main/java/org/linkeddatafragments/views/HtmlTriplePatternFragmentWriterImpl.java

@@ -106,7 +106,7 @@ public class HtmlTriplePatternFragmentWriterImpl extends TriplePatternFragmentWr
         // Calculate start and end triple number
         Long start = ((tpfRequest.getPageNumber() - 1) * fragment.getMaxPageSize()) + 1;
         data.put("start", start);
-        data.put("end", start + (triples.size() < fragment.getMaxPageSize() ? triples.size() : fragment.getMaxPageSize()));
+        data.put("end", (start - 1) + (triples.size() < fragment.getMaxPageSize() ? triples.size() : fragment.getMaxPageSize()));
         
         // Compose query object
         Map query = new HashMap();

api/src/main/java/org/vivoweb/linkeddatafragments/datasource/rdfservice/RDFServiceBasedRequestProcessorForTPFs.java

@@ -6,6 +6,9 @@ import edu.cornell.mannlib.vitro.webapp.rdfservice.RDFService;
 import edu.cornell.mannlib.vitro.webapp.rdfservice.RDFServiceException;
 import edu.cornell.mannlib.vitro.webapp.rdfservice.ResultSetConsumer;
 import org.apache.jena.atlas.io.StringWriterI;
+import org.apache.jena.graph.Node;
+import org.apache.jena.graph.NodeFactory;
+import org.apache.jena.graph.Triple;
 import org.apache.jena.query.Dataset;
 import org.apache.jena.query.Query;
 import org.apache.jena.query.QueryExecution;
@@ -19,6 +22,8 @@ import org.apache.jena.rdf.model.Literal;
 import org.apache.jena.rdf.model.Model;
 import org.apache.jena.rdf.model.ModelFactory;
 import org.apache.jena.rdf.model.RDFNode;
+import org.apache.jena.rdf.model.Statement;
+import org.apache.jena.rdf.model.StmtIterator;
 import org.apache.jena.riot.out.NodeFormatter;
 import org.apache.jena.riot.out.NodeFormatterTTL;
 import org.apache.jena.tdb.TDBFactory;
@@ -74,6 +79,32 @@ public class RDFServiceBasedRequestProcessorForTPFs
             return sw.toString();
         }
 
+        private Node skolemize(Node node) {
+            if (node != null && node.isBlank()) {
+                return NodeFactory.createURI("bnode://" + node.getBlankNodeLabel());
+            }
+
+            return node;
+        }
+
+        private RDFNode deskolemize(RDFNode node) {
+            if (node == null) {
+                return null;
+            }
+
+            if (node.isResource()) {
+                String uri = node.asResource().getURI();
+                if (uri != null && uri.startsWith("bnode://")) {
+                    String bnodeId = uri.substring(8);
+                    return ModelFactory.createDefaultModel().asRDFNode(
+                            NodeFactory.createBlankNode(bnodeId)
+                    );
+                }
+            }
+
+            return node;
+        }
+
         @Override
         protected ILinkedDataFragment createFragment(
                    final ITriplePatternElement<RDFNode,String,String> subject,
@@ -82,100 +113,51 @@ public class RDFServiceBasedRequestProcessorForTPFs
                    final long offset,
                    final long limit )
         {
-            StringBuilder whereClause = new StringBuilder();
-            StringBuilder filter = new StringBuilder();
-            StringBuilder orderBy = new StringBuilder();
-
-            if ( ! subject.isVariable() ) {
-                appendNode(whereClause.append(' '), subject.asConstantTerm());
-            } else {
-                whereClause.append(" ?s");
-                if (filter.length() > 0) { filter.append(" && "); }
-                filter.append("!isBlank(?s)");
-                orderBy.append(" ?s");
-            }
-
-            if ( ! predicate.isVariable() ) {
-                appendNode(whereClause.append(' '), predicate.asConstantTerm());
-            } else {
-                whereClause.append(" ?p");
-                if (filter.length() > 0) { filter.append(" && "); }
-                filter.append("!isBlank(?p)");
-                orderBy.append(" ?p");
-            }
-
-            if ( ! object.isVariable() ) {
-                appendNode(whereClause.append(' '), object.asConstantTerm());
-            } else {
-                whereClause.append(" ?o");
-                if (filter.length() > 0) { filter.append(" && "); }
-                filter.append("!isBlank(?o)");
-                orderBy.append(" ?o");
-            }
-
-            StringBuilder constructQuery = new StringBuilder();
-
-            constructQuery.append("CONSTRUCT { ");
-            constructQuery.append(whereClause.toString());
-            constructQuery.append(" } WHERE { ");
-            constructQuery.append(whereClause.toString()).append(" . ");
-            if (filter.length() > 0) {
-                constructQuery.append(" FILTER(").append(filter.toString()).append(")");
-            }
-            constructQuery.append(" }");
-
-            if (orderBy.length() > 0) {
-                constructQuery.append(" ORDER BY").append(orderBy.toString());
-            }
-
-            if (limit > 0) {
-                constructQuery.append(" LIMIT ").append(limit);
-            }
-
-            if (offset > 0) {
-                constructQuery.append(" OFFSET ").append(offset);
-            }
-
-            Model triples = ModelFactory.createDefaultModel();
-
             try {
-                rdfService.sparqlConstructQuery(constructQuery.toString(), triples);
+                RDFNode nSubject = subject.isVariable() ? null : deskolemize(subject.asConstantTerm());
+                RDFNode nPredicate = predicate.isVariable() ? null : deskolemize(predicate.asConstantTerm());
+                RDFNode nObject = object.isVariable() ? null : deskolemize(object.asConstantTerm());
+
+                Model triples = rdfService.getTriples(nSubject, nPredicate, nObject, limit, offset);
+                if (triples == null || triples.isEmpty()) {
+                    return createEmptyTriplePatternFragment();
+                }
+
+                if (triples.size() > 0) {
+                    Model replacedBlankNodes = ModelFactory.createDefaultModel();
+                    StmtIterator iter = triples.listStatements();
+                    while (iter.hasNext()) {
+                        Statement oldStmt = iter.next();
+                        Triple t = oldStmt.asTriple();
+                        replacedBlankNodes.add(
+                                replacedBlankNodes.asStatement(
+                                        new Triple(
+                                                skolemize(t.getSubject()),
+                                                skolemize(t.getPredicate()),
+                                                skolemize(t.getObject())
+                                        )
+                                )
+                        );
+                    }
+
+                    triples = replacedBlankNodes;
+                }
+
+                long size = triples.size();
+                long estimate = -1;
+                estimate = rdfService.countTriples(nSubject, nPredicate, nObject);
+
+                // No estimate or incorrect
+                if (estimate < offset + size) {
+                    estimate = (size == limit) ? offset + size + 1 : offset + size;
+                }
+
+                // create the fragment
+                final boolean isLastPage = ( estimate < offset + limit );
+                return createTriplePatternFragment( triples, estimate, isLastPage );
             } catch (RDFServiceException e) {
                 return createEmptyTriplePatternFragment();
             }
-
-            if (triples.isEmpty()) {
-                return createEmptyTriplePatternFragment();
-            }
-
-            // Try to get an estimate
-            long size = triples.size();
-            long estimate = -1;
-
-            StringBuilder count = new StringBuilder();
-            count.append("SELECT (COUNT(*) AS ?count) WHERE { ");
-            count.append(whereClause.toString());
-            count.append(" . ");
-            if (filter.length() > 0) {
-                count.append(" FILTER(").append(filter.toString()).append(") ");
-            }
-            count.append(" }");
-            try {
-                CountConsumer countConsumer = new CountConsumer();
-                rdfService.sparqlSelectQuery(count.toString(), countConsumer);
-                estimate = countConsumer.estimate;
-            } catch (RDFServiceException e) {
-                return createEmptyTriplePatternFragment();
-            }
-
-            // No estimate or incorrect
-            if (estimate < offset + size) {
-                estimate = (size == limit) ? offset + size + 1 : offset + size;
-            }
-
-            // create the fragment
-            final boolean isLastPage = ( estimate < offset + limit );
-            return createTriplePatternFragment( triples, estimate, isLastPage );
         }
 
     } // end of class Worker
@@ -186,16 +168,4 @@ public class RDFServiceBasedRequestProcessorForTPFs
      */
     public RDFServiceBasedRequestProcessorForTPFs() {
     }
-
-    class CountConsumer extends ResultSetConsumer {
-        public long estimate = -1;
-
-        @Override
-        protected void processQuerySolution(QuerySolution qs) {
-            if (estimate == -1) {
-                Literal literal = qs.getLiteral("count");
-                estimate = literal.getLong();
-            }
-        }
-    }
 }

api/src/main/java/org/vivoweb/linkeddatafragments/views/HtmlTriplePatternFragmentWriterImpl.java

@@ -124,7 +124,7 @@ public class HtmlTriplePatternFragmentWriterImpl extends TriplePatternFragmentWr
         // Calculate start and end triple number
         Long start = ((tpfRequest.getPageNumber() - 1) * fragment.getMaxPageSize()) + 1;
         data.put("start", start);
-        data.put("end", start + (triples.size() < fragment.getMaxPageSize() ? triples.size() : fragment.getMaxPageSize()));
+        data.put("end", (start - 1) + (triples.size() < fragment.getMaxPageSize() ? triples.size() : fragment.getMaxPageSize()));
         
         // Compose query object
         Map query = new HashMap();

api/src/main/resources/org/vivoweb/linkeddatafragments/servlet/ldf-client.css

@@ -0,0 +1,549 @@
+/*! @license MIT ©2014–2016 Ruben Verborgh, Ghent University – imec */
+
+html {
+    font-size: 11pt;
+    background: #f6f6f6;
+}
+html, input, textarea, button, pre {
+    font: 1em/1.4 'Open Sans', Verdana, Arial, sans-serif;
+    -webkit-text-size-adjust: none;
+}
+* {
+    outline: none !important;
+}
+
+body {
+    max-width: 650px;
+    margin: 0 auto;
+    padding: 1em 3em;
+    background: white;
+    box-shadow: 2px 2px 15px 0px rgba(50, 50, 50, 0.75);
+}
+
+a, button, label {
+    font-weight: bold;
+}
+a, button, input:hover, label {
+    color: #be1622;
+    cursor: pointer;
+    text-decoration: none;
+}
+a:hover {
+    color: #be1622;
+    text-decoration: underline;
+}
+
+button {
+    font-weight: bold;
+    color: black;
+    background-color: #f6f6f6;
+    border: 1px solid #999999;
+    border-radius: 3px;
+    margin: 0;
+    padding: 5px 8px;
+    cursor: pointer;
+}
+button:hover {
+    background-color: #ececec;
+}
+button:active {
+    margin: 1px -1px -1px 1px;
+}
+input {
+    padding: 1px 5px;
+    font-size: 10pt;
+}
+label:after {
+    content: ":";
+}
+
+header h1 {
+    margin: .3em 0 .1em;
+    font-size: 1.95em;
+}
+header p {
+    font-weight: bold;
+    margin: 0 0 1.5em;
+}
+header a {
+    color: inherit;
+}
+header .logo {
+    float: right;
+}
+header img {
+    margin: -9px -11px 0 0;
+    height: 81px;
+}
+
+main {
+    clear: both;
+}
+
+fieldset {
+    border: none;
+    padding: 0;
+    margin: 0;
+}
+.ldf-client, .ldf-client * {
+    max-width: 100%;
+}
+ul {
+    list-style: none;
+    padding: 0;
+    margin: 0;
+}
+fieldset > ul > li {
+    margin: .3em 0;
+    clear: both;
+}
+fieldset > ul > li:after {
+    content: "";
+    display: table;
+    clear: both;
+}
+
+select {
+    width: 430px;
+}
+
+.timing {
+    float: right;
+    font-size: 10pt;
+    padding: .7em 0;
+}
+
+.chosen {
+    float: right;
+}
+
+input.datetime {
+    float: right;
+    font-size: 13px;
+    border: 1px solid #999999;
+    border-radius: 3px;
+}
+
+.details {
+    display: none;
+}
+.details-toggle {
+    display: block;
+    width:  24px;
+    height: 24px;
+    margin: 0 -35px;
+    float: right;
+    cursor: pointer;
+    background: url(../images/memento.svg) no-repeat center center / contain;
+    opacity: .8;
+}
+.details-toggle:hover, .details-toggle.enabled {
+    opacity: 1;
+}
+.details-toggle.enabled {
+    background-image: url(../images/memento.svg#active);
+    width: 25px; /* for Chrome */
+}
+
+textarea {
+    box-sizing: border-box;
+    min-height: 11em;
+    width: 100%;
+    padding-left: 1em;
+    border: none;
+    cursor: pointer;
+    font-size: .95em;
+    background-color: transparent;
+}
+
+.results {
+    height: 23.5em;
+    font-size: 10pt;
+    margin: .5em 0 1em;
+}
+.results a {
+    font-weight: normal;
+    color: inherit;
+}
+.result {
+    width: calc(100% - 2px);
+}
+.result dl {
+    border: 1px solid #be1622;
+    margin: 0 0 1em;
+    border-radius: 5px;
+}
+.result dl:hover {
+    color: white;
+    background-color: #be1622;
+}
+.result dl:after {
+    content: "";
+    display: table;
+    clear: both;
+}
+.result dt {
+    float: left;
+    clear: left;
+    background-color: #be1622;
+    color: white;
+    font-style: normal;
+    font-weight: bold;
+    padding: 0 .5em;
+    margin: 0 .5em 0 0;
+}
+.result dd {
+    margin: 0 .5em 0 1em;
+}
+.result dt:last-of-type {
+    border-radius: 0 0 0 5px;
+}
+.results .text {
+    white-space: pre-wrap;
+    margin-right: -999999px; /* avoid that long URLs alter body width */
+}
+
+.log {
+    color: #666;
+    height: 6.3em;
+    font-size: 9pt;
+    line-height: 1.6;
+    margin: .5em -999999px 1em 0;
+}
+.log p {
+    margin: 0;
+}
+.log a {
+    font-weight: normal;
+}
+
+.results, .log {
+    width: 100%;
+    overflow: scroll;
+    -webkit-overflow-scrolling: touch;
+    position: relative;
+    contain: layout;
+}
+
+footer {
+    font-size: .8em;
+}
+
+@media (max-width: 725px) {
+    body {
+        padding: .1em 1em;
+        font-size: 10pt;
+    }
+    h1 {
+        font-size: 1.4em;
+    }
+    header img {
+        height: 70px;
+    }
+    header p {
+        margin: 0 0 .5em;
+    }
+
+    select {
+        width: 350px;
+    }
+    .chosen, input.datetime {
+        float: none;
+        margin-bottom: 0;
+    }
+    .details-toggle {
+        display: inline-block;
+        margin: 0 0 -8px 10px;
+    }
+
+    .log {
+        max-width: 90%;
+    }
+}
+
+@media (max-width: 550px) {
+    h1 {
+        ine-height: 1.2;
+    }
+    header p, .logo {
+        display: none;
+    }
+    label {
+        display: block;
+    }
+    select {
+        width: 250px;
+    }
+}
+
+
+
+/*
+ * Styling below derived from
+ * Chosen, a Select Box Enhancer for jQuery and Prototype
+ * by Patrick Filler for Harvest, http://getharvest.com
+ *
+ * Version 1.4.2
+ * Full source at https://github.com/harvesthq/chosen
+ * Copyright (c) 2011-2015 Harvest http://getharvest.com
+ *
+ * MIT License, https://github.com/harvesthq/chosen/blob/master/LICENSE.md
+*/
+
+.chosen {
+    position: relative;
+    display: inline-block;
+    vertical-align: middle;
+    font-size: 13px;
+    zoom: 1;
+    *display: inline;
+    user-select: none;
+}
+.chosen * {
+    box-sizing: border-box;
+}
+.chosen .chosen-drop {
+    position: absolute;
+    top: 100%;
+    left: -9999px;
+    z-index: 1010;
+    width: 100%;
+    border: 1px solid #999999;
+    border-top: 0;
+    background: #fff;
+}
+.chosen.chosen-with-drop .chosen-drop {
+    left: 0;
+}
+.chosen a {
+    cursor: pointer;
+}
+
+
+.chosen-single .chosen-single {
+    position: relative;
+    display: block;
+    overflow: hidden;
+    padding: 0 0 0 8px;
+    height: 25px;
+    border: 1px solid #999999;
+    border-radius: 3px;
+    background-color: #fff;
+    text-decoration: none;
+    white-space: nowrap;
+    line-height: 24px;
+    font-weight: normal;
+    color: inherit;
+}
+.chosen-single .chosen-single span {
+    display: block;
+    overflow: hidden;
+    margin-right: 26px;
+    text-overflow: ellipsis;
+    white-space: nowrap;
+}
+.chosen-single .chosen-single-with-deselect span {
+    margin-right: 38px;
+}
+.chosen-single .chosen-single abbr {
+    position: absolute;
+    top: 6px;
+    right: 26px;
+    display: block;
+    width: 12px;
+    height: 12px;
+    background: url('../images/chosen-sprite.png') -42px 1px no-repeat;
+    font-size: 1px;
+}
+.chosen-single .chosen-single abbr:hover {
+    background-position: -42px -10px;
+}
+.chosen-single .chosen-single div {
+    position: absolute;
+    top: 0;
+    right: 0;
+    display: block;
+    width: 18px;
+    height: 100%;
+}
+.chosen-single .chosen-single div b {
+    display: block;
+    width: 100%;
+    height: 100%;
+    background: url('../images/chosen-sprite.png') no-repeat 0px 2px;
+}
+.chosen-single .chosen-search {
+    position: relative;
+    z-index: 1010;
+    margin: 0;
+    padding: 3px 4px;
+    white-space: nowrap;
+}
+.chosen-single .chosen-search input[type="text"] {
+    margin: 1px 0;
+    padding: 4px 20px 4px 5px;
+    width: 100%;
+    height: auto;
+    outline: 0;
+    border: 1px solid #999999;
+    background: white url('../images/chosen-sprite.png') no-repeat 100% -20px;
+    background: url('../images/chosen-sprite.png') no-repeat 100% -20px;
+    font-size: 1em;
+    line-height: normal;
+    border-radius: 0;
+}
+.chosen-single .chosen-drop {
+    margin-top: -1px;
+    border-radius: 0 0 4px 4px;
+    background-clip: padding-box;
+}
+.chosen-single.chosen-single-nosearch .chosen-search {
+    position: absolute;
+    left: -9999px;
+}
+
+.chosen-results {
+    position: relative;
+    overflow-x: hidden;
+    overflow-y: auto;
+    margin: 0 4px 4px 0;
+    padding: 0 0 0 4px;
+    max-height: 240px;
+    -webkit-overflow-scrolling: touch;
+}
+.chosen-results li {
+    display: none;
+    margin: 0;
+    padding: 5px 6px;
+    list-style: none;
+    line-height: 15px;
+    word-wrap: break-word;
+    -webkit-touch-callout: none;
+}
+li.active-result {
+    display: list-item;
+    cursor: pointer;
+}
+li.highlighted {
+    background-color: #be1622;
+    color: #fff;
+}
+li.no-results {
+    display: none;
+}
+.chosen-results li em {
+    font-style: normal;
+    text-decoration: underline;
+}
+
+.chosen-choices {
+    position: relative;
+    overflow: hidden;
+    margin: 0;
+    padding: 0 5px;
+    width: 100%;
+    height: auto !important;
+    height: 1%;
+    border: 1px solid #999999;
+    border-radius: 3px;
+    background-color: #fff;
+    cursor: text;
+}
+.chosen-choices li {
+    float: left;
+    list-style: none;
+}
+li.search-field {
+    margin: 0;
+    padding: 0;
+    white-space: nowrap;
+}
+li.search-field input[type="text"] {
+    margin: 1px 0;
+    padding: 0;
+    height: 20px;
+    outline: 0;
+    border: 0 !important;
+    font-size: 100%;
+    line-height: normal;
+    border-radius: 0;
+}
+li.search-choice {
+    position: relative;
+    margin: 1px 5px 1px 0;
+    padding: 3px 20px 3px 5px;
+    max-width: 100%;
+    border-radius: 3px;
+    background-color: #f6f6f6;
+    border: 1px solid #cacaca;
+    line-height: 13px;
+    cursor: default;
+}
+li.search-choice:hover {
+    background-color: #ececec;
+}
+li.search-choice span {
+    word-wrap: break-word;
+}
+li.search-choice .search-choice-close {
+    position: absolute;
+    top: 4px;
+    right: 3px;
+    display: block;
+    width: 12px;
+    height: 12px;
+    background: url('../images/chosen-sprite.png') -42px 1px no-repeat;
+    font-size: 1px;
+}
+li.search-choice .search-choice-close:hover {
+    background-position: -42px -10px;
+}
+li.search-choice-focus {
+    background: #d4d4d4;
+}
+li.search-choice-focus .search-choice-close {
+    background-position: -42px -10px;
+}
+.chosen-results {
+    margin: 0;
+    padding: 0;
+}
+.chosen-drop .result-selected {
+    display: list-item;
+    cursor: default;
+}
+
+.chosen-active.chosen-with-drop .chosen-single {
+    border: 1px solid #999999;
+    border-bottom-right-radius: 0;
+    border-bottom-left-radius: 0;
+}
+.chosen-active.chosen-with-drop .chosen-single div {
+    border-left: none;
+}
+.chosen-active.chosen-with-drop .chosen-single div b {
+    background-position: -18px 2px;
+}
+.chosen-active .chosen-choices {
+    z-index: 100;
+    max-height: 500px;
+}
+
+
+@media only screen and (-webkit-min-device-pixel-ratio: 1.5), only screen and (min-resolution: 144dpi), only screen and (min-resolution: 1.5dppx) {
+    .chosen-rtl .chosen-search input[type="text"],
+    .chosen-single .chosen-single abbr,
+    .chosen-single .chosen-single div b,
+    .chosen-single .chosen-search input[type="text"],
+    .chosen-multi .chosen-choices .search-choice .search-choice-close,
+    .chosen .chosen-results-scroll-down span,
+    .chosen .chosen-results-scroll-up span {
+        background-image: url('../images/chosen-sprite@2x.png') !important;
+        background-size: 52px 37px !important;
+        background-repeat: no-repeat !important;
+    }
+}
+
+.results {
+    line-height: 1.5em;
+}

api/src/main/resources/org/vivoweb/linkeddatafragments/servlet/style.css

@@ -85,7 +85,7 @@ legend {
 }
 
 label {
-  width: 100px;
+  width: 200px;
   display: block;
   float: left;
   clear: both;

api/src/main/resources/tpf/client.ftl.html

@@ -0,0 +1,43 @@
+<h2>Query from your browser</h2>
+<p>
+    Your browser executes these queries locally
+    using <a href="http://linkeddatafragments.org/in-depth/#tpf" target="_blank">Triple Pattern Fragments</a>.
+</p>
+<fieldset class="ldf-client">
+    <ul>
+        <li>
+            <label>Query</label>
+            <textarea class="queryText"></textarea>
+        </li>
+        <li>
+            <button class="start" style="display: inline-block;">Execute query</button>
+            <button class="stop" style="display: none;">Stop execution</button>
+            <span class="timing"></span>
+        </li>
+        <!-- example queries -->
+        <li>
+            <label>Query results</label>
+            <div class="results"><div class="text"></div><div class="scrollRunway" style="position: absolute; height: 1px; width: 1px; transition: transform 0.2s; -webkit-transition: transform 0.2s; transform: translate(0px, 0px);"> </div></div>
+        </li>
+    </ul>
+</fieldset>
+<link rel="stylesheet" href="${ assetsPath }ldf-client.css">
+<script>
+    var ldfAssetsPath = '${ assetsPath }';
+</script>
+<script src="${ assetsPath }ldf-client-ui-packaged.js"></script>
+<script>jQuery(function($){$(".ldf-client").queryui(
+    {
+        "datasources": [
+            <#if datasources??>
+                <#list datasources?keys as datasourceName>
+                    {
+                        "name": "${datasources[datasourceName].getTitle() }",
+                        "url": "${homePath}/${datasourceName}"
+                    }<#if datasourceName?has_next>, </#if>
+                </#list>
+            </#if>
+        ]
+
+    }
+)})</script>

api/src/main/resources/tpf/examples.ftl.html

@@ -0,0 +1,122 @@
+<li>
+    <label>Example queries</label>
+    <select class="query" style="display: none;"><option></option><option value="SELECT ?movie ?title ?name
+WHERE {
+  ?movie dbpedia-owl:starring [ rdfs:label &quot;Brad Pitt&quot;@en ];
+         rdfs:label ?title;
+         dbpedia-owl:director [ rdfs:label ?name ].
+  FILTER LANGMATCHES(LANG(?title), &quot;EN&quot;)
+  FILTER LANGMATCHES(LANG(?name),  &quot;EN&quot;)
+}">Directors of movies starring Brad Pitt</option><option value="SELECT DISTINCT ?entity WHERE {
+  ?entity a dbpedia-owl:Airport;
+          dbpprop:cityServed dbpedia:Italy.
+}">Airports in Italy</option><option value="SELECT ?name ?deathDate WHERE {
+  ?person a dbpedia-owl:Artist;
+          rdfs:label ?name;
+          dbpedia-owl:birthPlace [ rdfs:label &quot;York&quot;@en ].
+  FILTER LANGMATCHES(LANG(?name),  &quot;EN&quot;)
+  OPTIONAL { ?person dbpprop:dateOfDeath ?deathDate. }
+}">Artists born in York</option><option value="CONSTRUCT {
+  ?artist a dbpedia-owl:Artist.
+  ?artist dbpedia-owl:birthDate ?date.
+}
+WHERE {
+  ?artist dbpedia-owl:influencedBy dbpedia:Pablo_Picasso.
+  ?artist a dbpedia-owl:Artist.
+  ?artist dbpedia-owl:birthDate ?date.
+}">Artists influenced by Picasso</option><option value="SELECT DISTINCT ?book ?author
+WHERE {
+  ?book rdf:type dbpedia-owl:Book;
+        dbpedia-owl:author ?author.
+}
+LIMIT 100">Authors of books</option><option value="SELECT ?award WHERE {
+  ?award a dbpedia-owl:Award;
+         dbpprop:country [ dbpedia-owl:language dbpedia:Dutch_language ].
+}">Award ceremonies in Dutch speaking countries</option><option value="SELECT DISTINCT ?performer ?name WHERE {
+  ?work dbpedia-owl:writer dbpedia:Michael_Jackson;
+        dbpedia-owl:musicalArtist ?performer.
+  OPTIONAL {
+    ?performer rdfs:label ?name.
+    FILTER LANGMATCHES(LANG(?name), &quot;EN&quot;)
+  }
+}">Bands Michael Jackson wrote a song for</option><option value="SELECT ?software ?company WHERE {
+  ?software dbpedia-owl:developer ?company.
+  ?company dbpedia-owl:locationCountry [ rdfs:label &quot;Belgium&quot;@en ].
+}">Belgian software</option><option value="PREFIX yago: &lt;http://dbpedia.org/class/yago/&gt;
+SELECT ?person
+WHERE {
+  ?person a yago:Carpenters, yago:PeopleExecutedByCrucifixion.
+}">Carpenters killed by crucifixion</option><option value="PREFIX dbpedia-owl: &lt;http://dbpedia.org/ontology/&gt;
+SELECT ?actor ?cause
+WHERE {
+  ?actor dbpedia-owl:deathCause ?cause.
+  ?actor dc:subject &lt;http://dbpedia.org/resource/Category:American_male_film_actors&gt;
+}">Death causes of male American actors</option><option value="SELECT ?dessert ?fruit
+WHERE {
+  ?dessert dbpedia-owl:type &lt;http://dbpedia.org/resource/Dessert&gt;;
+           dbpedia-owl:ingredient ?fruit.
+  ?fruit dbpedia-owl:kingdom &lt;http://dbpedia.org/resource/Plant&gt;.
+}">Desserts made with plants</option><option value="SELECT DISTINCT ?device WHERE {
+  dbpedia:Raspberry_Pi dbpprop:os ?operatingSystem.
+  ?device a dbpedia-owl:Device;
+          dbpprop:os ?operatingSystem.
+  FILTER (!(?device = dbpedia:Raspberry_Pi))
+}">Devices with the same OS as the Raspberry Pi</option><option value="SELECT DISTINCT ?entity ?event
+WHERE {
+  ?entity a dbpedia-owl:Event;
+          rdfs:label ?event;
+          ?predicate &lt;http://dbpedia.org/resource/Trentino&gt; .
+  FILTER(langMatches(lang(?event), &quot;EN&quot;))
+}">Events that took place in the Trentino region</option><option value="SELECT ?titleEng ?title
+WHERE {
+    ?movie dbpprop:starring [ rdfs:label &quot;Natalie Portman&quot;@en ];
+           rdfs:label ?titleEng, ?title.
+    FILTER LANGMATCHES(LANG(?titleEng), &quot;EN&quot;)
+    FILTER (!LANGMATCHES(LANG(?title), &quot;EN&quot;))
+}">Foreign titles of Natalie Portman movies</option><option value="SELECT ?indDish ?belDish ?ingredient
+WHERE {
+  ?indDish a dbpedia-owl:Food;
+           dbpedia-owl:origin dbpedia:India;
+           dbpedia-owl:ingredient ?ingredient.
+  ?belDish a dbpedia-owl:Food;
+           dbpedia-owl:origin dbpedia:Belgium;
+           dbpedia-owl:ingredient ?ingredient.
+}">Indian dishes that have ingredients in common with Belgian dishes</option><option value="SELECT DISTINCT ?artist ?band ?bandName WHERE {
+  { &lt;http://dbpedia.org/resource/Queen_(band)&gt; dbpedia-owl:bandMember ?artist. }
+  UNION
+  { &lt;http://dbpedia.org/resource/Queen_(band)&gt; dbpedia-owl:formerBandMember ?artist. }
+  ?band dbpedia-owl:formerBandMember ?artist;
+        rdfs:label ?bandName.
+  FILTER (?band != &lt;http://dbpedia.org/resource/Queen_(band)&gt;)
+}">Other bands of Queen members</option><option value="SELECT DISTINCT ?person
+WHERE {
+  dbpedia:Jesus dc:subject ?common.
+  ?person a foaf:Person;
+          dc:subject ?common.
+}
+LIMIT 1000">People who have something in common with Jesus</option><option value="SELECT ?place ?relation
+WHERE {
+  ?place rdf:type dbpedia-owl:Settlement;
+         ?relation dbpedia:Barack_Obama;
+}">Places that have something to do with Barack Obama</option><option value="SELECT ?clubName ?playerName WHERE {
+  ?club a dbpedia-owl:SoccerClub;
+        dbpedia-owl:ground ?city;
+        rdfs:label ?clubName.
+  ?player dbpedia-owl:team ?club;
+          dbpedia-owl:birthPlace ?city;
+          rdfs:label ?playerName.
+  ?city dbpedia-owl:country dbpedia:Spain.
+
+  FILTER LANGMATCHES(LANG(?clubName), &quot;EN&quot;)
+  FILTER LANGMATCHES(LANG(?playerName), &quot;EN&quot;)
+}">Soccer players born in their club's city</option><option value="SELECT ?entity ?label ?comment
+WHERE {
+  ?entity a dbpedia-owl:MythologicalFigure;
+          rdfs:label ?label;
+          dc:subject &lt;http://dbpedia.org/resource/Category:Women_in_Greek_mythology&gt;;
+          rdfs:comment ?comment
+
+  FILTER(langMatches(lang(?label), &quot;EN&quot;))
+  FILTER(langMatches(lang(?comment), &quot;EN&quot;))
+}">Women in Greek mythology</option></select><div class="chosen chosen-single" style="width: 430px;" title=""><a class="chosen-single chosen-default" tabindex="-1"><span> </span><div><b></b></div></a><div class="chosen-drop"><div class="chosen-search"><input type="text" autocomplete="off"></div><ul class="chosen-results"></ul></div></div>
+</li>

api/src/main/resources/tpf/index.ftl.html

@@ -12,10 +12,9 @@
     </#list>
     </#if>
   </dl>
-  <p>The current dataset <em class="dataset">index</em> contains metadata about these datasets.</p>
 </div>
 
-<#include "fragment.ftl.html">
+<#include "client.ftl.html">
 </#macro>
 
 <@display_page/>