1. A method for a data processing system, comprising: enabling a user to specify policy information for use by a persistence manager in determining how to persist information relating to a data item to achieve a desired level of reliability, by: permitting the user to specify at least two behavior requirements to be associated with information to be persisted, a first behavior requirement being specifiable for a first system state and a second behavior state being specifiable for a second system state, the behavior requirements being interpretable by the persistence manager to determine a persistence behavior necessary to conform with the policy information.