A flexible graphical user interface for performance modeling

We identify three goals for the graphical user interface (GUI) of a network simulation environment: user friendliness, model re-usability, and application extensibility. We address the user-friendliness issue by proposing a simple yet efficient approach to setup parameters for the simulation models. We address the application extensibility issue with a two-layer GUI architecture. The two layers are loosely coupled, and the first layer can be easily replaced without affecting the other components of the simulation environment. The concept of subnetwork is used to address the model reusability issue. Unlike most existing simulation packages, where a subnetwork is simply a method to group the nodes, the subnetwork construct in our approach is a first-class citizen in the simulation environment (i.e., all operations for a basic node also apply to a subnetwork). The port concept is used to define the I/O relationship between a subnetwork and the outside world. Parameter dialog boxes are used to set up the parameters for a subnetwork conveniently. Finally, a simple stack mechanism is used to measure subnetwork-wide output statistics.