1. A system for managing requests from at least one external network, the system comprising: a firewall configured to determine one or more resources a requestor is attempting to access; a policy repository; one or more security policy management servers configured to: receive an authorization request from the firewall, wherein the request comprises information about the requestor and a resource name; retrieve, from the policy repository, a dynamically-loadable security access policy associated with the named resource, wherein the dynamically-loadable security access policy comprises one or more rules that indicate conditions under which a request to perform an action on the resource should be granted; determine at least one attribute required by at least one of the rules of the dynamically-loadable security access policy retrieved from the policy repository and associated with the named resource: for at least one of the attributes required by a rule of the dynamically-loadable security access policy retrieved from the policy repository and associated with the named resource, determine whether an attribute value must be requested from a remote data source; request at least one of the attribute values required by a rule of the dynamically-loadable security access policy retrieved from the policy repository and associated with the named resource that must be requested from the remote data source; retrieve from the remote data source the at least one of the attribute values; evaluate the dynamically-loadable security access policy retrieved from the policy repository and associated with the named resource using the at least one of the attribute values from the remote data source; and return an authorization decision to the firewall.