diff --git a/base/src/main/java/de/staropensource/sosengine/base/Engine.java b/base/src/main/java/de/staropensource/sosengine/base/Engine.java
index be7c9b2..d55f4cc 100644
--- a/base/src/main/java/de/staropensource/sosengine/base/Engine.java
+++ b/base/src/main/java/de/staropensource/sosengine/base/Engine.java
@@ -19,6 +19,7 @@
 
 package de.staropensource.sosengine.base;
 
+import de.staropensource.sosengine.base.classes.SubsystemMainClass;
 import de.staropensource.sosengine.base.data.info.EngineInformation;
 import de.staropensource.sosengine.base.events.EngineShutdownEvent;
 import de.staropensource.sosengine.base.events.internal.InternalEngineShutdownEvent;
@@ -42,7 +43,7 @@ import java.util.Map;
  * @since 1-alpha0
  */
 @SuppressWarnings({ "unused", "JavadocDeclaration", "JavadocBlankLines" })
-public final class Engine {
+public final class Engine implements SubsystemMainClass {
     /**
      * Instance.
      *
diff --git a/base/src/main/java/de/staropensource/sosengine/base/classes/SubsystemMainClass.java b/base/src/main/java/de/staropensource/sosengine/base/classes/SubsystemMainClass.java
new file mode 100644
index 0000000..b658b48
--- /dev/null
+++ b/base/src/main/java/de/staropensource/sosengine/base/classes/SubsystemMainClass.java
@@ -0,0 +1,51 @@
+/*
+ * STAROPENSOURCE ENGINE SOURCE FILE
+ * Copyright (c) 2024 The StarOpenSource Engine Contributors
+ * Licensed under the GNU Affero General Public License v3
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package de.staropensource.sosengine.base.classes;
+
+import de.staropensource.sosengine.base.Engine;
+import de.staropensource.sosengine.base.annotations.EventListener;
+import de.staropensource.sosengine.base.events.internal.InternalEngineShutdownEvent;
+import de.staropensource.sosengine.base.logging.LoggerInstance;
+
+/**
+ * The interface for engine subsystem main classes.
+ *
+ * @since 1-alpha0
+ */
+@SuppressWarnings({ "unused" })
+public interface SubsystemMainClass {
+    /**
+     * Logger instance.
+     *
+     * @see LoggerInstance
+     * @since 1-alpha0
+     */
+    LoggerInstance logger = null;
+
+    /**
+     * Called when the engine shuts down.
+     *
+     * @see Engine#shutdown()
+     * @see Engine#shutdown(int)
+     * @since 1-alpha0
+     */
+    @EventListener(event = InternalEngineShutdownEvent.class)
+    static void shutdown() {}
+}