1. A method for network traffic control, comprising: accepting, as a result of computing hardware and programmable memory, by a first traffic controller, as part of a first traffic-classification module, a first use by an administrative user of a first type of programming language statement, the first type of statement including a first event identifier and a first scope specification, wherein the first scope specification contains a first description of a first functionality to be performed, when an event of a first type, as specified by the first event identifier, occurs; executing, as a result of computing hardware and programmable memory, on the first traffic controller, a traffic control application that includes a first collection of traffic-classification modules, wherein each module is capable of identifying a traffic type, for association with a session, and the first traffic-classification module is included in the first collection of traffic-classification modules; identifying, as a result of computing hardware and programmable memory, a first packet, flowing from a source network device to a destination network device, as a subject of traffic-type classification, the first packet produced in response to an action by an end-user; identifying, as a result of computing hardware and programmable memory, a first session from the first packet; determining, as a result of computing hardware and programmable memory, whether the first packet is an event of the first event type and, if it is, executing the first module; and processing, as a result of computing hardware and programmable memory, the first packet in accordance with at least a default policy.