Access Control
If the service is to be freely available to all people with access to the same communications network, then no access control is necessary. If not, there will need to be mechanism put in place to give permission to access the material.

If the end-user interface is provided through the WWW, then the security mechanisms available with most web servers access can be used to restrict access generally so that only requests coming from specific hosts get through, or on a user by user basis by requiring that a correct username and password be entered before giving access to the service.