1. A method of controlling application usage and document access in a plurality of computers the method comprising: evaluating at least one rule pertaining to an occurrence of an event; wherein the at least one rule is among a plurality of rules stored on a first computer; wherein the at least one rule contains at least one expression used by the evaluating step to decide whether to perform an action; communicating with a plurality of computers as indicated by the at least one rule; and instructing the plurality of computers to perform an action as indicated by the at least one rule.