diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/httputils/HTTPCall.java b/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/httputils/HTTPCall.java
index e38c5a4..0ab4c2c 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/httputils/HTTPCall.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/api/rest/httputils/HTTPCall.java
@@ -64,7 +64,7 @@ public class HTTPCall {
 	}
 	
 	protected String getParametersDataString(
-			Map<String, String> parameters)
+			Map<String, ? extends Object> parameters)
 			throws UnsupportedEncodingException {
 		
 		if (parameters == null) {
@@ -79,11 +79,9 @@ public class HTTPCall {
 			} else {
 				result.append(PARAM_SEPARATOR);
 			}
-
 			result.append(URLEncoder.encode(key, UTF8));
 			result.append(PARAM_EQUALS);
-			result.append(URLEncoder.encode(parameters.get(key), UTF8));
-
+			result.append(URLEncoder.encode(String.valueOf(parameters.get(key)), UTF8));
 		}
 
 		return result.toString();
@@ -158,7 +156,7 @@ public class HTTPCall {
 			
 			DataOutputStream wr = new DataOutputStream(
 					connection.getOutputStream());
-			wr.writeBytes(body);
+			wr.writeBytes(URLEncoder.encode(body, UTF8));
 			wr.flush();
 			wr.close();
 		}
@@ -226,7 +224,7 @@ public class HTTPCall {
 		return call(clz, path, method, null, null);
 	}
 	
-	public <C> C call(Class<C> clz, String path, HTTPMETHOD method, Map<String, String> parameters) throws Exception {
+	public <C> C call(Class<C> clz, String path, HTTPMETHOD method, Map<String, ? extends Object> parameters) throws Exception {
 		return call(clz, path, method, parameters, null);
 	}
 	
@@ -235,7 +233,7 @@ public class HTTPCall {
 	}
 	
 	@SuppressWarnings("unchecked")
-	protected <C> C call(Class<C> clz, String path, HTTPMETHOD method, Map<String, String> parameters, String body) throws Exception {
+	protected <C> C call(Class<C> clz, String path, HTTPMETHOD method, Map<String, ? extends Object> parameters, String body) throws Exception {
 		
 		String urlParameters = getParametersDataString(parameters);
 		
diff --git a/src/main/java/org/gcube/informationsystem/resourceregistry/api/utils/Utility.java b/src/main/java/org/gcube/informationsystem/resourceregistry/api/utils/Utility.java
index 448da37..e77eac8 100644
--- a/src/main/java/org/gcube/informationsystem/resourceregistry/api/utils/Utility.java
+++ b/src/main/java/org/gcube/informationsystem/resourceregistry/api/utils/Utility.java
@@ -6,6 +6,7 @@ import java.util.UUID;
 import org.gcube.informationsystem.impl.utils.ISMapper;
 import org.gcube.informationsystem.model.ER;
 import org.gcube.informationsystem.model.ISManageable;
+import org.gcube.informationsystem.types.TypeBinder;
 
 import com.fasterxml.jackson.annotation.JsonTypeName;
 import com.fasterxml.jackson.core.JsonProcessingException;
@@ -41,6 +42,15 @@ public abstract class Utility {
 	}
 	
 	public static String getType(ISManageable isManageable){
-		return isManageable.getClass().getAnnotation(JsonTypeName.class).value();
+		return getType(isManageable.getClass());
 	}
+	
+	public static String getType(Class<? extends ISManageable> clz){
+		if(!clz.isInterface()){
+			return clz.getAnnotation(JsonTypeName.class).value();
+		}else {
+			return TypeBinder.getType(clz);
+		}
+	}
+	
 }