diff --git a/Kwf/Assets/Dependency/HttpUrl.php b/Kwf/Assets/Dependency/HttpUrl.php
index <HASH>..<HASH> 100644
--- a/Kwf/Assets/Dependency/HttpUrl.php
+++ b/Kwf/Assets/Dependency/HttpUrl.php
@@ -39,4 +39,14 @@ class Kwf_Assets_Dependency_HttpUrl extends Kwf_Assets_Dependency_Abstract
             throw new Kwf_Exception("Unknown file type");
         }
     }
+
+    public function getContentsPacked()
+    {
+        return null;
+    }
+
+    public function getIdentifier()
+    {
+        return $this->_url;
+    }
 }
assets dependency httpUrl supports now new abstract methods from <I>