1. A method, comprising: in a computerized private network system with a host and one or more clients in communication with the host, instantiating a client session associated with a particular client that interfaces with a server application on the host, the server application having one or more screens associated therewith, each screen containing one or more fields; establishing in an application-layer monitor a connection with the server application for the instantiated client session, the application-layer monitor being deployed on the host and logically interposed between the server application on the host and the particular client; selecting a field from the one or more fields; defining a rule configured to monitor the field for a pre-set condition, the rule initiating an action when the rule is met; associating the rule to the field; and uploading the rule to the application-layer monitor for subsequent run-time use, the application-layer monitor being configured to substantially in real-time copy all communications between the client and the application on the host and to apply the rule to-field to evaluate activity embodied in client-server communications to determine whether the evaluated activity meets the rule, the action being configured to initiate when the evaluated activity meets the rule.