The evaluation of a policy can be delayed until all rules criteria needed
for evaluation are available. Also, new types of rules criteria can be
registered without requiring changes to a rules engine. A policy manager
allows rules to be evaluated and decisions made at different stages of
the request handling. The policy manager facilitates interaction with the
rules engine until all criteria are evaluated. The policy manager also
allows modules developed by third parties to provide notification when
criteria can be decided and thus complete evaluation.