Role based security ?

Hello,

Is there some way to enforce "role-based" security on different 
services/components deployed in Merlin ?

Ex:
I want user X to have access to services A, B and C
user Y to have access to services C and D only

Please let me know if this is possible currently and if yes, how and if not 
what is the best way to achieve this.

Thanks,
--Ravi