diff --git a/src/main/java/org/gcube/gcat/api/interfaces/Configuration.java b/src/main/java/org/gcube/gcat/api/interfaces/Configuration.java
index 4356895..be4c8e5 100644
--- a/src/main/java/org/gcube/gcat/api/interfaces/Configuration.java
+++ b/src/main/java/org/gcube/gcat/api/interfaces/Configuration.java
@@ -13,11 +13,11 @@ public interface Configuration<C,D> {
 	
 	public C create(String json) throws WebServiceException;
 	
-	public String read() throws WebServiceException ;
+	public C read() throws WebServiceException ;
+
+	public C update(String json) throws WebServiceException;
 	
-	public String update(String json) throws WebServiceException;
-	
-	public String patch(String json) throws WebServiceException;
+	public C patch(String json) throws WebServiceException;
 	
 	public D delete() throws WebServiceException;