diff --git a/java/com.sap.sailing.datamining/src/com/sap/sailing/datamining/Aggregator.java b/java/com.sap.sailing.datamining/src/com/sap/sailing/datamining/Aggregator.java
new file mode 100644
index 00000000000..5f24a930101
--- /dev/null
+++ b/java/com.sap.sailing.datamining/src/com/sap/sailing/datamining/Aggregator.java
@@ -0,0 +1,9 @@
+package com.sap.sailing.datamining;
+
+import java.util.Collection;
+
+public interface Aggregator {
+    
+    public double aggregate(Collection<GPSFixWithContext> data);
+
+}
diff --git a/java/com.sap.sailing.datamining/src/com/sap/sailing/datamining/Grouper.java b/java/com.sap.sailing.datamining/src/com/sap/sailing/datamining/Grouper.java
new file mode 100644
index 00000000000..ee9fcb5c84a
--- /dev/null
+++ b/java/com.sap.sailing.datamining/src/com/sap/sailing/datamining/Grouper.java
@@ -0,0 +1,10 @@
+package com.sap.sailing.datamining;
+
+import java.util.Collection;
+import java.util.Map;
+
+public interface Grouper<K> {
+
+    public Map<K, Collection<GPSFixWithContext>> group(Collection<GPSFixWithContext> data);
+    
+}