1. A method of operating a central processor configuring a web application server firewall, which enabled inside a web application server, to process HTTP request messages and HTTP response messages received from at least one client computer in accordance with a plurality of security rules, said method comprising the steps of: building a plurality of HTTP message models having parent portions and child portions, said plurality of HTTP message models including a first HTTP message model configured to process said HTTP request messages and a second HTTP message model configured to process said HTTP response messages, each of said first and second HTTP message models comprising a plurality of message model sections; developing said plurality of security rules, each security rule specifying at least one action responsive to a given condition, said given condition being based, at least in part, on a corresponding section of a message intercepted by said web application server firewall; and binding said plurality of security rules to said message model sections, wherein said binding comprises inheriting, by at least one child portion of at least one of the plurality of HTTP message models, at least one of said plurality of security rules from at least one of the parent portions of said at least one of the plurality of HTTP message models.