This invention relates to a method of and an apparatus for providing an interface between a client and one or more data storage systems. Existing approaches to the management of multiple, distributed heterogeneous data storage systems are deficient in that they are inflexible to change. To alleviate these deficiencies there is provided a method of providing an interface between a client (307) and one or more data storage systems (309). The method comprises the steps of receiving a request from a client (307), searching, in a rule store populated by modifiable human-readable rules each specifying a handler for use in responding to client requests, for a human readable rule and providing the interface by activating the handler specified in the human readable rule to communicate with the data storage systems.