@abc.abstractmethod<EOL><INDENT>def synchronize_installations(self):<DEDENT>
pass<EOL>
Performs an auto-update by adding all new updated installations and removing of all obsolete installations on
        the site.

        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

        *compliance: mandatory -- This method must be implemented.*