This disclosure describes a network flow framework that generates customized network applications based upon user inputs that invokes various software building block functions to process ingress data packets. The network flow framework creates a network application pointer that points to the customized network application, and stores the network application pointer with application classification keys in a classification entry. When the network flow framework receives an ingress data packet, the network flow framework matches the ingress packet's classification key to the application classification key in the classification entry. As such, the network flow framework retrieves the network application pointer from the classification entry and stores the network application pointer in the ingress data packet's header. In turn, the network flow framework retrieves the customized network application corresponding to the network application pointer and processes the ingress data packet accordingly.