1. A system for state managing an operating system and applications, the system comprising: a plurality of repositories including instances of state information; at least one processor; and a memory connected to the at least one processor, the memory comprising: instructions for the at least one processor to implement an aggregator to provide a single point of access to instances of state information by the operating system and the applications, the aggregator being further for accessing definitions of data types corresponding to the instances of the state information and for accessing the data types and the instances of the state information either directly or through a layered stack, the data types defining rules with respect to valid values for the instances of the state information; a policy denoting how to provide a merged view of the instances of the state information included in a plurality of repositories, the policy being for use by the aggregator to provide the merged view of the instances of the state information, the layered stack being defined by the policy; and instructions for the at least one processor to implement a referential integrity enforcer to ensure referential integrity with respect to the instances of the state information.