diff -r bd1a76c91d5b -r b213fef2539e src/java/de/uapcore/lightpit/ModuleManager.java
--- a/src/java/de/uapcore/lightpit/ModuleManager.java	Sat Mar 31 19:35:04 2018 +0200
+++ b/src/java/de/uapcore/lightpit/ModuleManager.java	Sun Apr 01 18:16:47 2018 +0200
@@ -28,11 +28,11 @@
  */
 package de.uapcore.lightpit;
 
+import de.uapcore.lightpit.entities.CoreDAOFactory;
+import de.uapcore.lightpit.entities.ModuleDao;
 import java.sql.Connection;
-import java.sql.PreparedStatement;
-import java.sql.ResultSet;
 import java.sql.SQLException;
-import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
@@ -41,6 +41,7 @@
 import java.util.Optional;
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.stream.Collectors;
 import javax.servlet.Registration;
 import javax.servlet.ServletContext;
 import javax.servlet.ServletContextEvent;
@@ -66,7 +67,7 @@
     /**
      * This flag is true, when synchronization is needed.
      */
-    private AtomicBoolean dirty = new AtomicBoolean(true);
+    private final AtomicBoolean dirty = new AtomicBoolean(true);
     
     private final CopyOnWriteArrayList<Menu> mainMenu = new CopyOnWriteArrayList<>();
     private final List<Menu> immutableMainMenu = Collections.unmodifiableList(mainMenu);
@@ -140,10 +141,12 @@
      * Scans for modules and reloads them all.
      */
     public void reloadAll() {
+        registeredModules.clear();
         sc.getServletRegistrations().forEach(this::handleServletRegistration);
         
         // TODO: implement dependency resolver
         
+        dirty.set(true);
         LOG.info("Modules loaded.");
     }
     
@@ -156,36 +159,20 @@
         if (dirty.compareAndSet(true, false)) {
             if (db.getDataSource().isPresent()) {
                 try (Connection conn = db.getDataSource().get().getConnection()) {
-                    PreparedStatement
-                            check = conn.prepareStatement("SELECT visible FROM lpitcore_module WHERE classname = ?"),
-                            insert = conn.prepareStatement("INSERT INTO lpitcore_module (classname, visible) VALUES (?, ?)");
-                    insert.setBoolean(2, true);
-                    // update/delete not required, we do this in the module management UI
+                    final ModuleDao moduleDao = CoreDAOFactory.getModuleDao(db.getSQLDialect());
                     
-                    final List<Menu> updatedMenu = new ArrayList<>();
+                    final List<Entry<String, LightPITModule>> visibleModules =
+                            moduleDao.syncRegisteredModuleClasses(conn, registeredModules.entrySet());
                     
-                    for (Entry<String, LightPITModule> mod : registeredModules.entrySet()) {
-                        if (mod.getValue().systemModule()) continue;
-                        
-                        check.setString(1, mod.getKey());
-                        try (ResultSet r = check.executeQuery()) {
-                            final boolean addToMenu;
-                            if (r.next()) {
-                                addToMenu = r.getBoolean(1);
-                            } else {
-                                insert.setString(1, mod.getKey());
-                                insert.executeUpdate();
-                                addToMenu = !mod.getValue().menuKey().isEmpty();
-                            }
-                            if (addToMenu) {
-                                updatedMenu.add(new Menu(
-                                        mod.getKey(),
-                                        new ResourceKey(mod.getValue().bundleBaseName(), mod.getValue().menuKey()),
-                                        mod.getValue().modulePath()
-                                ));
-                            }
-                        }
-                    }
+                    final List<Menu> updatedMenu = visibleModules
+                            .stream()
+                            .collect(Collectors.mapping(
+                                    (mod) -> new Menu(
+                                            mod.getKey(),
+                                            new ResourceKey(mod.getValue().bundleBaseName(), mod.getValue().menuKey()),
+                                            mod.getValue().modulePath()),
+                                    Collectors.toList())
+                            );
                     
                     mainMenu.removeIf((e) -> !updatedMenu.contains(e));
                     mainMenu.addAllAbsent(updatedMenu);
@@ -205,6 +192,7 @@
      */
     public void unloadAll() {
         mainMenu.clear();
+        registeredModules.clear();
         LOG.info("All modules unloaded.");
     }
 
@@ -215,4 +203,15 @@
     public List<Menu> getMainMenu() {
         return immutableMainMenu;
     }
+    
+    /**
+     * Returns an unmodifiable map of all registered modules.
+     * 
+     * The key is the classname of the module.
+     * 
+     * @return the map of registered modules
+     */
+    public Map<String, LightPITModule> getRegisteredModules() {
+        return Collections.unmodifiableMap(registeredModules);
+    }
 }