[Freeswitch-users] May FS module Application NOT return data like FS module API?

Hi folks,   I looked into a few modules (e.g. mod_db, mod_hash, mod_unimrcp, mod_skel and mod_say_xx), and find out that unlike module api,  a module app seems not able to return any data. If so, how do we know operation result after we submit app request to FS? for example,  <action application="appx" data="run/my/data"/> how do I know the above app task is executed successfully or not?xk