A system, a computer device implemented method, and a computer readable article of manufacture for executing a computer implemented method for a unified access control for a plurality of composed services in a distributed computing environment without requiring repeated input of security certification. The method includes the steps of: acquiring a first role of a user in a first composed service; sending an invoking request by a processing unit of the first composed service to a second composed service; receiving the first role of the user in the first composed service and predefined role-role mapping relationships, and determining a second role of the user in the second composed service by a role determining component; and then sending the determined role in the second composed service by a role sending component to the second composed service, thereby providing unified access without requiring repeated input of security certification.