diff --git a/APED/app/src/main/java/com/example/aped/communication/IIO.java b/APED/app/src/main/java/com/example/aped/communication/IIO.java
index 7b178a3..9c7f5b5 100644
--- a/APED/app/src/main/java/com/example/aped/communication/IIO.java
+++ b/APED/app/src/main/java/com/example/aped/communication/IIO.java
@@ -1,8 +1,19 @@
 package com.example.aped.communication;
 
-public interface IIO {
+public interface IIO
+{
+    /**
+     * reads a value from a device connected to the raspberry
+     * @param deviceName the name of the device to read from
+     * @return the value read
+     */
+    String read(String deviceName);
 
-    public Object read(String deviceName);
-
-    public Object write(String deviceName, Object value);
+    /**
+     * writes a value to a device connected to the raspberry
+     * @param deviceName the name of the device to write to
+     * @param value the value to write to the device
+     * @return the value written
+     */
+    String write(String deviceName, String value);
 }
diff --git a/APED/app/src/main/java/com/example/aped/communication/IXML.java b/APED/app/src/main/java/com/example/aped/communication/IXML.java
index 880941a..0c2b4a0 100644
--- a/APED/app/src/main/java/com/example/aped/communication/IXML.java
+++ b/APED/app/src/main/java/com/example/aped/communication/IXML.java
@@ -1,16 +1,38 @@
 package com.example.aped.communication;
 
+import java.util.Dictionary;
+import java.util.List;
+
 public interface IXML {
     /**
-     *
-     * @return hat Funktioniert?
+     * downloads the XML from the raspberry to the local folder
+     * @return 0 for no errors
      */
     int download();
 
     /**
-     *
-     * @return hat Funktioniert?
+     * uploads the local XML to the raspberry
+     * @return 0 for no errors
      */
     int upload();
 
+    /**
+     * reads the list of available devices from the XML
+     * @return the device names as a list of strings
+     */
+    List<String> getDeviceNames();
+
+    /**
+     * reads the value info of a given device from the XML
+     * @param deviceName the name of the relevant device
+     * @return the value info as a Dictionary
+     */
+    Dictionary<String, Object> getValueInfo(String deviceName);
+
+    /**
+     * reads the port information of a given device from the XML
+     * @param deviceName the name of the relevant device
+     * @return the value info as a Dictionary
+     */
+    Dictionary<String, Object> getPort(String deviceName);
 }
diff --git a/APED/app/src/main/java/com/example/aped/communication/TestIO.java b/APED/app/src/main/java/com/example/aped/communication/TestIO.java
index 3ddfc0c..eb07aae 100644
--- a/APED/app/src/main/java/com/example/aped/communication/TestIO.java
+++ b/APED/app/src/main/java/com/example/aped/communication/TestIO.java
@@ -3,12 +3,12 @@ package com.example.aped.communication;
 public class TestIO implements IIO {
 
     @Override
-    public Object read(String deviceName) {
-        return new String("test");
+    public String read(String deviceName) {
+        return "test";
     }
 
     @Override
-    public Object write(String deviceName, Object value) {
+    public String write(String deviceName, String value) {
         return value;
     }
 }
diff --git a/APED/app/src/main/java/com/example/aped/communication/TestXML.java b/APED/app/src/main/java/com/example/aped/communication/TestXML.java
index 0b43443..3e043d4 100644
--- a/APED/app/src/main/java/com/example/aped/communication/TestXML.java
+++ b/APED/app/src/main/java/com/example/aped/communication/TestXML.java
@@ -1,6 +1,11 @@
 package com.example.aped.communication;
 
 
+import java.util.ArrayList;
+import java.util.Dictionary;
+import java.util.Hashtable;
+import java.util.List;
+
 public class TestXML implements IXML {
     /** Test Klasse.*/
     @Override
@@ -12,4 +17,33 @@ public class TestXML implements IXML {
     public int upload() {
         return 0;
     }
+
+    @Override
+    public List<String> getDeviceNames() {
+        List<String> returnList = new ArrayList<>();
+        returnList.add("stoff");
+        returnList.add("schnaps");
+        return returnList;
+    }
+
+    @Override
+    public Dictionary<String, Object> getValueInfo(String deviceName) {
+        Dictionary<String,Object> returnDict = new Hashtable<>();
+        returnDict.put("type","boolean");
+        returnDict.put("unit","");
+        returnDict.put("Offset",1.0);
+        returnDict.put("Factor",1.0);
+        return returnDict;
+    }
+
+    @Override
+    public Dictionary<String, Object> getPort(String deviceName) {
+        Dictionary<String, Object> returnDict = new Hashtable<>();
+        returnDict.put("protocol","DI");
+        Dictionary<String,Object> pins = new Hashtable<>();
+        pins.put("GPIO2",true);
+        pins.put("GPIO3",false);
+        returnDict.put("pins",pins);
+        return returnDict;
+    }
 }