diff --git a/src/main/java/org/gcube/common/storagehub/model/storages/StorageBackend.java b/src/main/java/org/gcube/common/storagehub/model/storages/StorageBackend.java
index c3db008..096f2f5 100644
--- a/src/main/java/org/gcube/common/storagehub/model/storages/StorageBackend.java
+++ b/src/main/java/org/gcube/common/storagehub/model/storages/StorageBackend.java
@@ -33,9 +33,9 @@ public abstract class StorageBackend {
 	
 	public abstract void delete(String id);
 	
-	public abstract MetaInfo upload(InputStream stream, String relativePath, String name);
+	public abstract MetaInfo upload(InputStream stream, String relativePath, String name, String user);
 	
-	public abstract MetaInfo upload(InputStream stream, String relativePath, String name, Long size);
+	public abstract MetaInfo upload(InputStream stream, String relativePath, String name, Long size, String user);
 	
 	public abstract InputStream download(Content item) throws StorageIdNotFoundException;
 	
@@ -43,7 +43,7 @@ public abstract class StorageBackend {
 	
 	public abstract Map<String, String> getFileMetadata(String id);
 	
-	public abstract MetaInfo upload(InputStream stream, String relativePath, String name, String storageId, Long size);
+	public abstract MetaInfo upload(InputStream stream, String relativePath, String name, String storageId, Long size, String user);
 	
 	@Deprecated
 	public abstract String getTotalSizeStored();