diff --git a/src/foundation/pEp/jniadapter/AbstractEngine.java b/src/foundation/pEp/jniadapter/AbstractEngine.java
index f492ccb..496c118 100644
--- a/src/foundation/pEp/jniadapter/AbstractEngine.java
+++ b/src/foundation/pEp/jniadapter/AbstractEngine.java
@@ -8,7 +8,7 @@ import foundation.pEp.jniadapter.Sync.DefaultCallback;
 import java.io.UnsupportedEncodingException;
 import java.text.Normalizer;
 
-abstract class AbstractEngine extends UniquelyIdentifiable implements AutoCloseable {
+abstract class AbstractEngine extends UniquelyIdentifiable implements AbstractEngineInterface, AutoCloseable {
     static {
         System.loadLibrary("pEpJNI");
     }
@@ -34,18 +34,46 @@ abstract class AbstractEngine extends UniquelyIdentifiable implements AutoClosea
         }
     }
 
-    public native String getVersion();
-    public native String getProtocolVersion();
+    private native String _getVersion();
+
+    public String getVersion() {
+        return _getVersion();
+    }
+
+    private native String _getProtocolVersion();
+
+    public String getProtocolVersion() {
+        return _getProtocolVersion();
+    }
 
     private long keyserverThread;
     private long keyserverQueue;
 
-    public native void startKeyserverLookup();
-    public native void stopKeyserverLookup();
+    private native void _startKeyserverLookup();
+
+    public void startKeyserverLookup() {
+        _startKeyserverLookup();
+    }
+
+    private native void _stopKeyserverLookup();
+
+    public void stopKeyserverLookup() {
+        _startKeyserverLookup();
+    }
+
+    private native void _startSync();
+
+    public void startSync() {
+        _startSync();
+    }
+
+    private native void _stopSync();
+
+    public void stopSync() {
+        _stopSync();
+    }
 
-    public native void startSync();
-    public native void stopSync();
-    public native boolean isSyncRunning();
+    private native boolean _isSyncRunning();
 
     public static byte[] toUTF8(String str) {
         if (str == null)
diff --git a/src/foundation/pEp/jniadapter/AbstractEngineInterface.java b/src/foundation/pEp/jniadapter/AbstractEngineInterface.java
new file mode 100644
index 0000000..9b13206
--- /dev/null
+++ b/src/foundation/pEp/jniadapter/AbstractEngineInterface.java
@@ -0,0 +1,31 @@
+package foundation.pEp.jniadapter;
+
+public interface AbstractEngineInterface {
+    public String getVersion();
+
+    public String getProtocolVersion();
+
+    public void startKeyserverLookup();
+
+    public void stopKeyserverLookup();
+
+    public void startSync();
+
+    public void stopSync();
+
+    public boolean isSyncRunning();
+
+    public void setMessageToSendCallback(Sync.MessageToSendCallback messageToSendCallback);
+
+    public void setNotifyHandshakeCallback(Sync.NotifyHandshakeCallback notifyHandshakeCallback);
+
+    public void setNeedsFastPollCallback(Sync.NeedsFastPollCallback needsFastPollCallback);
+
+    public int needsFastPollCallFromC(boolean fast_poll_needed);
+
+    public int notifyHandshakeCallFromC(_Identity _myself, _Identity _partner, SyncHandshakeSignal _signal);
+
+    public int messageToSendCallFromC(Message message);
+
+    public Message incomingMessageFromPGPText(String pgpText, Message.EncFormat encFormat);
+}
diff --git a/src/foundation_pEp_jniadapter_AbstractEngine.cc b/src/foundation_pEp_jniadapter_AbstractEngine.cc
index beb06ef..8511fb7 100644
--- a/src/foundation_pEp_jniadapter_AbstractEngine.cc
+++ b/src/foundation_pEp_jniadapter_AbstractEngine.cc
@@ -196,7 +196,7 @@ JNIEXPORT void JNICALL Java_foundation_pEp_jniadapter_AbstractEngine_release(
     Adapter::session(pEp::Adapter::release);
 }
 
-JNIEXPORT jstring JNICALL Java_foundation_pEp_jniadapter_AbstractEngine_getVersion(
+JNIEXPORT jstring JNICALL Java_foundation_pEp_jniadapter_AbstractEngine__1getVersion(
         JNIEnv *env,
         jobject obj
     )
@@ -212,7 +212,7 @@ JNIEXPORT jstring JNICALL Java_foundation_pEp_jniadapter_AbstractEngine_getVersi
     return env->NewStringUTF(::get_engine_version());
 }
 
-JNIEXPORT jstring JNICALL Java_foundation_pEp_jniadapter_AbstractEngine_getProtocolVersion(
+JNIEXPORT jstring JNICALL Java_foundation_pEp_jniadapter_AbstractEngine__1getProtocolVersion(
         JNIEnv *env,
         jobject obj
     )
@@ -263,7 +263,7 @@ static void *keyserver_thread_routine(void *arg)
     return (void *) status;
 }
 
-JNIEXPORT void JNICALL Java_foundation_pEp_jniadapter_AbstractEngine_startKeyserverLookup(
+JNIEXPORT void JNICALL Java_foundation_pEp_jniadapter_AbstractEngine__1startKeyserverLookup(
         JNIEnv *env,
         jobject obj
     )
@@ -307,7 +307,7 @@ JNIEXPORT void JNICALL Java_foundation_pEp_jniadapter_AbstractEngine_startKeyser
     pthread_create(thread, nullptr, keyserver_thread_routine, (void *) queue);
 }
 
-JNIEXPORT void JNICALL Java_foundation_pEp_jniadapter_AbstractEngine_stopKeyserverLookup(
+JNIEXPORT void JNICALL Java_foundation_pEp_jniadapter_AbstractEngine__1stopKeyserverLookup(
         JNIEnv *env,
         jobject obj
     )
@@ -351,7 +351,7 @@ JNIEXPORT void JNICALL Java_foundation_pEp_jniadapter_AbstractEngine_stopKeyserv
     free(thread);
 }
 
-JNIEXPORT void JNICALL Java_foundation_pEp_jniadapter_AbstractEngine_startSync(
+JNIEXPORT void JNICALL Java_foundation_pEp_jniadapter_AbstractEngine__1startSync(
         JNIEnv *env,
         jobject obj
     )
@@ -374,7 +374,7 @@ JNIEXPORT void JNICALL Java_foundation_pEp_jniadapter_AbstractEngine_startSync(
     }
 }
 
-JNIEXPORT void JNICALL Java_foundation_pEp_jniadapter_AbstractEngine_stopSync(
+JNIEXPORT void JNICALL Java_foundation_pEp_jniadapter_AbstractEngine__1stopSync(
         JNIEnv *env,
         jobject obj
     )
@@ -390,7 +390,7 @@ JNIEXPORT void JNICALL Java_foundation_pEp_jniadapter_AbstractEngine_stopSync(
     Adapter::shutdown();
 }
 
-JNIEXPORT jboolean JNICALL Java_foundation_pEp_jniadapter_AbstractEngine_isSyncRunning(
+JNIEXPORT jboolean JNICALL Java_foundation_pEp_jniadapter_AbstractEngine__1isSyncRunning(
         JNIEnv *env,
         jobject obj
     )