access control

[Zohar]

Hello list,
I have a few servlets which are deployed to different contexts (each servlet to 
its own context).
One of these servlets acts as an interface to clients, and it forwards the 
requests from clients to the appropriate servlets.
I don't want any of the non-interface servlets to be accessible to clients (but 
they must still be accessible to the interface servlet). 
How do I do that?
Thanks,
Zohar.