added a 'DataSourceTypesRegistry' and classes to represent the existing data source types (HdtDataSourceType and JenaTDBDataSourceType)

Author: Olaf Hartig

src/org/linkeddatafragments/datasource/DataSourceTypesRegistry.java

@@ -0,0 +1,36 @@
+package org.linkeddatafragments.datasource;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * A registry of {@link IDataSourceType}s.
+ *
+ * @author <a href="http://olafhartig.de">Olaf Hartig</a>
+ */
+public class DataSourceTypesRegistry
+{
+    private static Map<String, IDataSourceType> registry =
+                                        new HashMap<String, IDataSourceType>();
+
+    public static synchronized IDataSourceType getType( final String typeName )
+    {
+        return registry.get( typeName );
+    }
+
+    public static synchronized boolean isRegistered( final String typeName )
+    {
+        return registry.containsKey( typeName );
+    }
+
+    public static synchronized void register( final String typeName,
+                                              final IDataSourceType type )
+    {
+        if ( registry.containsKey(typeName) ) {
+            throw new IllegalArgumentException( "The registry already " +
+                       "contains a type with the name '" + typeName + "'." );
+        }
+        registry.put( typeName, type );
+    }
+
+}

src/org/linkeddatafragments/datasource/HdtDataSourceType.java

@@ -0,0 +1,42 @@
+package org.linkeddatafragments.datasource;
+
+import java.io.File;
+import java.io.IOException;
+
+import org.linkeddatafragments.exceptions.DataSourceException;
+
+import com.google.gson.JsonObject;
+
+/**
+ * The type of HDT-backed Triple Pattern Fragment data sources.
+ *
+ * @author <a href="http://olafhartig.de">Olaf Hartig</a>
+ */
+public class HdtDataSourceType implements IDataSourceType
+{
+    public static final String TYPE_NAME = "HdtDatasource";
+
+    public static void register() {
+        if ( ! DataSourceTypesRegistry.isRegistered(TYPE_NAME) ) {
+            DataSourceTypesRegistry.register( TYPE_NAME,
+                                              new HdtDataSourceType() );
+        }
+    }
+
+    @Override
+    public IDataSource createDataSource( final String title,
+                                         final String description,
+                                         final JsonObject settings )
+                                                     throws DataSourceException
+    {
+        final String fname = settings.getAsJsonPrimitive("file").getAsString();
+        final File file = new File( fname );
+        
+        try {
+            return new HdtDataSource(title, description, file.getAbsolutePath());
+        } catch (IOException ex) {
+            throw new DataSourceException(ex);
+        }
+    }
+
+}

src/org/linkeddatafragments/datasource/IDataSourceType.java

@@ -0,0 +1,32 @@
+package org.linkeddatafragments.datasource;
+
+import org.linkeddatafragments.exceptions.DataSourceException;
+
+import com.google.gson.JsonObject;
+
+/**
+ * Represents types of {@link IDataSource}s that can be used to provide some
+ * Linked Data Fragments interface.
+ *
+ * @author <a href="http://olafhartig.de">Olaf Hartig</a>
+ */
+public interface IDataSourceType
+{
+    /**
+     * Creates a data source of this type.
+     * 
+     * @param title
+     *        The title of the data source (as given in the config file).
+     * 
+     * @param description
+     *        The description of the data source (as given in the config file).
+     *
+     * @param settings
+     *        The properties of the data source to be created; usually, these
+     *        properties are given in the config file of the LDF server. 
+     */
+    IDataSource createDataSource( final String title,
+                                  final String description,
+                                  final JsonObject settings )
+                                                    throws DataSourceException;
+}

src/org/linkeddatafragments/datasource/JenaTDBDataSourceType.java

@@ -0,0 +1,42 @@
+package org.linkeddatafragments.datasource;
+
+import java.io.File;
+
+import org.linkeddatafragments.exceptions.DataSourceException;
+
+import com.google.gson.JsonObject;
+
+/**
+ * The type of Triple Pattern Fragment data sources that are backed by
+ * a Jena TDB instance.
+ *
+ * @author <a href="http://olafhartig.de">Olaf Hartig</a>
+ */
+public class JenaTDBDataSourceType implements IDataSourceType
+{
+    public static final String TYPE_NAME = "JenaTDBDatasource";
+
+    public static void register() {
+        if ( ! DataSourceTypesRegistry.isRegistered(TYPE_NAME) ) {
+            DataSourceTypesRegistry.register( TYPE_NAME,
+                                              new JenaTDBDataSourceType() );
+        }
+    }
+
+    @Override
+    public IDataSource createDataSource( final String title,
+                                         final String description,
+                                         final JsonObject settings )
+                                                     throws DataSourceException
+    {
+        final String dname = settings.getAsJsonPrimitive("directory").getAsString();
+        final File dir = new File( dname );
+
+        try {
+            return new JenaTDBDataSource(title, description, dir);
+        } catch (Exception ex) {
+            throw new DataSourceException(ex);
+        }
+    }
+
+}