11. A system for enforcing application-layer policies to documents, each policy defining a rule and an action, comprising: a XML parser for parsing a XML document received as streaming XML data in a hierarchical structure to enable evaluation of an object in the XML document; a simple policies data structure for storing XPath queries that do not use wildcard “*” and descendent “//” expressions; a complex policies data structure for storing XPath queries that use wildcard “*” and descendent “//” expressions; means for simultaneously querying the simple and complex policies data structures to identify all policies corresponding to the object; and means for executing the actions defined by the policies corresponding to the object identified in the data structures.
11. A system for enforcing application-layer policies to documents, each policy defining a rule and an action, comprising: a XML parser for parsing a XML document received as streaming XML data in a hierarchical structure to enable evaluation of an object in the XML document; a simple policies data structure for storing XPath queries that do not use wildcard “*” and descendent “//” expressions; a complex policies data structure for storing XPath queries that use wildcard “*” and descendent “//” expressions; means for simultaneously querying the simple and complex policies data structures to identify all policies corresponding to the object; and means for executing the actions defined by the policies corresponding to the object identified in the data structures. 12. The system of claim 11 , wherein the simple policies data structure is filtered by a Deterministic Finite Automaton (DFA) structure.