1. A method for controlling access rights to dynamically instantiated portal applications in a portal environment, wherein new instances of a portal application and respective access control information on resources used in the application are generated dynamically from an automated programmed mechanism, and wherein a user-application role mapping is demanded for the portal application by a respective runtime access control function implemented at the portal environment, comprising: assigning an individual user-to-application role mapping to a respective individual one of the created instances of the portal application, wherein for each incoming user request to one of the created instances the runtime access control function checks a target application instance identifier, which identifies an individual application instance desired to be addressed by the incoming request; and granting access rights to incoming user requests according to the application roles as they are defined for the target application instance.