1. A method of operating a computer system to provide a user interface to a data storage system, said computer system including a rule store storing one or more rules, said method comprising the steps: providing a user interface to said rule store enabling user configuration of said rule store with one or more rules, each rule including information relating to a handler program, said handler program being associated with one or more user requirements and being operable to interact with said data storage system in accordance with said user requirements; receiving a request detailing one or more user requirements; responsive to receipt of said request: a) searching said rule store for a rule associating said one or more user requirements of said received request with a handler program; b) running said handler program to interact with said data storage system.