diff -r 986ee928a866 -r 16a1925df2df annot-server/websockets.py
--- a/annot-server/websockets.py	Tue Oct 14 05:07:37 2014 +0200
+++ b/annot-server/websockets.py	Tue Oct 14 08:12:54 2014 +0200
@@ -93,13 +93,17 @@
         }
 
         def error_callback(failure):
-            raise http.HttpException(500,"Error when processing message : %r" % failure)
+            res = params.copy()
+            res['status'] = 'KO'
+            res['failure'] = str(failure)
+            self.sendMessage(json.dumps(res))
 
         def annot_callback(res):
             if 'ts' in res:
                 res['ts'] = res['ts'].isoformat()+'Z'
             if 'uuid' in res:
                 res['uuid'] = str(res['uuid'])
+            res['status'] = 'OK'
             self.sendMessage(json.dumps(res))