OK,
I created a web service. This web service is called by a client. A create a user in mws and create an ACL in IS. I gave execution permission et read execution to my web service to the ACL and I put my user in ACL.
When I call the WS by a clent, no problem.
But this web service call another web service coming from another package and when I start my ws with administrator user, no probleme but if I do it with my specific user (created) I have a denied authorizaton.
I wonder how th change user during a call of a flow service