diff -r fd8c40ff78c3 -r 824d4042c857 src/main/java/de/uapcore/lightpit/DatabaseFacade.java
--- a/src/main/java/de/uapcore/lightpit/DatabaseFacade.java	Sat May 09 15:19:21 2020 +0200
+++ b/src/main/java/de/uapcore/lightpit/DatabaseFacade.java	Sat May 09 17:01:29 2020 +0200
@@ -1,8 +1,8 @@
 /*
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
- * 
+ *
  * Copyright 2018 Mike Becker. All rights reserved.
- * 
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
@@ -24,10 +24,12 @@
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
- * 
+ *
  */
 package de.uapcore.lightpit;
 
+import de.uapcore.lightpit.dao.DataAccessObjects;
+import de.uapcore.lightpit.dao.postgres.PGDataAccessObjects;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -57,6 +59,9 @@
      */
     private static final int DB_TEST_TIMEOUT = 10;
 
+    /**
+     * Specifies the database dialect.
+     */
     public enum Dialect {
         Postgres
     }
@@ -64,21 +69,21 @@
     /**
      * The database dialect to use.
      * <p>
-     * May be override by context parameter.
+     * May be overridden by context parameter.
      *
      * @see Constants#CTX_ATTR_DB_DIALECT
      */
     private Dialect dialect = Dialect.Postgres;
-    
+
     /**
      * The default schema to test against when validating the connection.
-     * 
+     * <p>
      * May be overridden by context parameter.
-     * 
+     *
      * @see Constants#CTX_ATTR_DB_SCHEMA
      */
     private static final String DB_DEFAULT_SCHEMA = "lightpit";
-    
+
     /**
      * The attribute name in the Servlet context under which an instance of this class can be found.
      */
@@ -86,21 +91,31 @@
 
     private static final String DS_JNDI_NAME = "jdbc/lightpit/app";
     private DataSource dataSource;
-    
+    private DataAccessObjects dataAccessObjects;
+
     /**
      * Returns the data source.
-     * 
+     * <p>
      * The Optional returned should never be empty. However, if something goes
      * wrong during initialization, the data source might be absent.
      * Hence, users of this data source are forced to check the existence.
-     * 
+     *
      * @return a data source
      */
     public Optional<DataSource> getDataSource() {
         // TODO: this should not be an optional, if an empty optional is actually an exception
         return Optional.ofNullable(dataSource);
     }
-    
+
+    /**
+     * Returns the data access objects.
+     *
+     * @return an interface to obtain the data access objects
+     */
+    public DataAccessObjects getDataAccessObjects() {
+        return dataAccessObjects;
+    }
+
     public Dialect getSQLDialect() {
         return dialect;
     }
@@ -138,9 +153,9 @@
     @Override
     public void contextInitialized(ServletContextEvent sce) {
         ServletContext sc = sce.getServletContext();
-        
+
         dataSource = null;
-        
+
         final String contextName = Optional
                 .ofNullable(sc.getInitParameter(Constants.CTX_ATTR_JNDI_CONTEXT))
                 .orElse("java:comp/env");
@@ -156,6 +171,8 @@
             }
         }
 
+        dataAccessObjects = createDataAccessObjects(dialect);
+
         try {
             LOG.debug("Trying to access JNDI context {}...", contextName);
             Context initialCtx = new InitialContext();
@@ -169,13 +186,22 @@
         } catch (NamingException | ClassCastException ex) {
             LOG.error("Cannot access JNDI resources.", ex);
         }
-        
+
         sc.setAttribute(SC_ATTR_NAME, this);
         LOG.info("Database facade injected into ServletContext.");
     }
 
+    private static DataAccessObjects createDataAccessObjects(Dialect dialect) {
+        switch (dialect) {
+            case Postgres:
+                return new PGDataAccessObjects();
+            default:
+                throw new AssertionError("Non-exhaustive switch - this is a bug.");
+        }
+    }
+
     @Override
     public void contextDestroyed(ServletContextEvent sce) {
         dataSource = null;
-    }    
+    }
 }