Merge pull request #5 from LinkedDataFragments/master

merging in latest changes from origin

Author: hartig

config-example.json

@@ -1,6 +1,11 @@
 {
   "title": "My Linked Data Fragments server",
 
+  "datasourcetypes": {
+    "HdtDatasource"       : "org.linkeddatafragments.datasource.hdt.HdtDataSourceType",
+    "JenaTDBDatasource"   : "org.linkeddatafragments.datasource.tdb.JenaTDBDataSourceType"
+  },
+
   "datasources": {
     "dbpedia": {
       "title": "DBPedia",

src/org/linkeddatafragments/config/ConfigReader.java

@@ -5,6 +5,8 @@
 import java.util.Map;
 import java.util.Map.Entry;
 
+import org.linkeddatafragments.datasource.IDataSourceType;
+
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
 import com.google.gson.JsonParser;
@@ -13,8 +15,10 @@
  * Reads the configuration of a Linked Data Fragments server.
  *
  * @author Ruben Verborgh
+ * @author <a href="http://olafhartig.de">Olaf Hartig</a>
  */
 public class ConfigReader {
+    private final Map<String, IDataSourceType> dataSourceTypes = new HashMap<>();
     private final Map<String, JsonObject> dataSources = new HashMap<>();
     private final Map<String, String> prefixes = new HashMap<>();
     private final String baseURL;
@@ -28,6 +32,10 @@ public ConfigReader(Reader configReader) {
         JsonObject root = new JsonParser().parse(configReader).getAsJsonObject();
         this.baseURL = root.has("baseURL") ? root.getAsJsonPrimitive("baseURL").getAsString() : null;
 
+        for (Entry<String, JsonElement> entry : root.getAsJsonObject("datasourcetypes").entrySet()) {
+            final String className = entry.getValue().getAsString();
+            dataSourceTypes.put(entry.getKey(), initDataSouceType(className) );
+        }
         for (Entry<String, JsonElement> entry : root.getAsJsonObject("datasources").entrySet()) {
             JsonObject dataSource = entry.getValue().getAsJsonObject();
             this.dataSources.put(entry.getKey(), dataSource);
@@ -37,6 +45,15 @@ public ConfigReader(Reader configReader) {
         }
     }
 
+    /**
+     * Gets the data source types.
+     *
+     * @return a mapping of names of data source types to these types  
+     */
+    public Map<String, IDataSourceType> getDataSourceTypes() {
+        return dataSourceTypes;
+    }
+
     /**
      * Gets the data sources.
      *
@@ -58,4 +75,35 @@ public Map<String, String> getPrefixes() {
     public String getBaseURL() {
         return baseURL;
     }
+
+    protected IDataSourceType initDataSouceType( final String className )
+    {
+        final Class<?> c;
+        try {
+            c = Class.forName( className ); 
+        }
+        catch ( ClassNotFoundException e ) {
+            throw new IllegalArgumentException( "Class not found: " + className,
+                                                e );
+        }
+
+        final Object o;
+        try {
+            o = c.newInstance();
+        }
+        catch ( Exception e ) {
+            throw new IllegalArgumentException(
+                        "Creating an instance of class '" + className + "' " +
+                        "caused a " + e.getClass().getSimpleName() + ": " +
+                        e.getMessage(), e );
+        }
+
+        if ( ! (o instanceof IDataSourceType) )
+            throw new IllegalArgumentException(
+                        "Class '" + className + "' is not an implementation " +
+                        "of IDataSourceType." );
+
+        return (IDataSourceType) o;
+    }
+
 }

src/org/linkeddatafragments/datasource/AbstractJenaBasedRequestProcessorForTriplePatterns.java

@@ -1,41 +1,52 @@
 package org.linkeddatafragments.datasource;
 
+import com.hp.hpl.jena.rdf.model.Model;
+
 import org.linkeddatafragments.fragments.LinkedDataFragment;
 import org.linkeddatafragments.fragments.LinkedDataFragmentRequest;
+import org.linkeddatafragments.fragments.tpf.TriplePatternElement;
 import org.linkeddatafragments.fragments.tpf.TriplePatternFragment;
 import org.linkeddatafragments.fragments.tpf.TriplePatternFragmentImpl;
 import org.linkeddatafragments.fragments.tpf.TriplePatternFragmentRequest;
 
-import com.hp.hpl.jena.rdf.model.Model;
-
 /**
  * Base class for implementations of {@link IFragmentRequestProcessor} that
  * process {@link TriplePatternFragmentRequest}s.
  *
+ * @param <TermType> type for representing RDF terms in triple patterns 
+ * @param <VarType> type for representing specific variables in triple patterns
+ *
  * @author <a href="http://olafhartig.de">Olaf Hartig</a>
  */
-public abstract class AbstractRequestProcessorForTriplePatterns
-    extends AbstractRequestProcessor
+public abstract class
+    AbstractRequestProcessorForTriplePatterns<TermType,VarType>
+        extends AbstractRequestProcessor
 {
     @Override
-    protected Worker getWorker( final LinkedDataFragmentRequest request )
+    protected final Worker<TermType,VarType> getWorker(
+            final LinkedDataFragmentRequest request )
                                                 throws IllegalArgumentException
     {
-        if ( request instanceof TriplePatternFragmentRequest )
-            return getWorker( (TriplePatternFragmentRequest) request );
+        if ( request instanceof TriplePatternFragmentRequest<?,?> ) {
+            @SuppressWarnings("unchecked")
+            final TriplePatternFragmentRequest<TermType,VarType> tpfRequest =
+                      (TriplePatternFragmentRequest<TermType,VarType>) request;
+            return getTPFSpecificWorker( tpfRequest );
+        }
         else
             throw new IllegalArgumentException( request.getClass().getName() );
     }
 
-    abstract protected Worker getWorker(
-            final TriplePatternFragmentRequest request )
+    abstract protected Worker<TermType,VarType> getTPFSpecificWorker(
+            final TriplePatternFragmentRequest<TermType,VarType> request )
                     throws IllegalArgumentException;
 
 
-    abstract static protected class Worker
+    abstract static protected class Worker<TermType,VarType>
         extends AbstractRequestProcessor.Worker
     {        
-        public Worker( final TriplePatternFragmentRequest request )
+        public Worker(
+                 final TriplePatternFragmentRequest<TermType,VarType> request )
         {
             super( request );
         }
@@ -51,20 +62,22 @@ public LinkedDataFragment createRequestedFragment()
             else
                 offset = 0L;
 
-            final TriplePatternFragmentRequest tpfRequest =
-                                        (TriplePatternFragmentRequest) request;
+            @SuppressWarnings("unchecked")
+            final TriplePatternFragmentRequest<TermType,VarType> tpfRequest =
+                      (TriplePatternFragmentRequest<TermType,VarType>) request;
 
             return createFragment( tpfRequest.getSubject(),
                                    tpfRequest.getPredicate(),
                                    tpfRequest.getObject(),
                                    offset, limit );
         }
 
-        abstract protected LinkedDataFragment createFragment( final String subj,
-                                                              final String pred,
-                                                              final String obj,
-                                                              final long offset,
-                                                              final long limit )
+        abstract protected LinkedDataFragment createFragment(
+                            final TriplePatternElement<TermType,VarType> subj,
+                            final TriplePatternElement<TermType,VarType> pred,
+                            final TriplePatternElement<TermType,VarType> obj,
+                            final long offset,
+                            final long limit )
                                                throws IllegalArgumentException;
 
         protected TriplePatternFragment createEmptyTriplePatternFragment()
@@ -78,17 +91,11 @@ protected TriplePatternFragment createTriplePatternFragment(
                                                      final long totalSize,
                                                      final boolean isLastPage )
         {
-            final long pageNumber;
-            if ( request.isPageRequest() )
-                pageNumber = request.getPageNumber();
-            else
-                pageNumber = 1L;
-
             return new TriplePatternFragmentImpl( triples,
                                                   totalSize,
                                                   request.getFragmentURL(),
                                                   request.getDatasetURL(),
-                                                  pageNumber,
+                                                  request.getPageNumber(),
                                                   isLastPage );
         }
 

src/org/linkeddatafragments/datasource/AbstractRequestProcessorForTriplePatterns.java

@@ -1,10 +1,5 @@
 package org.linkeddatafragments.datasource;
 
-import org.linkeddatafragments.fragments.IFragmentRequestParser;
-import org.linkeddatafragments.fragments.LinkedDataFragmentRequest;
-import org.linkeddatafragments.fragments.tpf.TPFRequestParser;
-import org.linkeddatafragments.fragments.tpf.TriplePatternFragmentRequest;
-
 /**
  *
  * @author mielvandersande
@@ -29,19 +24,6 @@ public String getTitle() {
         return this.title;
     };
 
-    /**
-     * This implementation assumes that requests are
-     * {@link TriplePatternFragmentRequest}s.
-     *
-     * Data sources for other types of {@link LinkedDataFragmentRequest}s must
-     * override this method accordingly.
-     */
-    @Override
-    public IFragmentRequestParser getRequestParser()
-    {
-        return new TPFRequestParser();
-    }
-
     @Override
     public void close() {}
 }