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Implementation Details

To provide as much flexibility as possible, the display application is implemented as multiple nearly-independent modules. Each module is responsible for the display of a particular kind of data and is implemented using both a C file and a Tcl/Tk script. Transmission of requests and reception of responses related to that display type are handled in the C file. The C code converts the simulator response into a form useful by Tcl and then invokes a Tcl procedure to perform the display action. The Tcl file implements the user interface for the data display maintained by the module.

Figure 2: Sample simulation display.

One such display module is used to illustrate the path a simulated connection takes through the network, as shown in Figure 2. These path displays are either transient, in which case they are automatically removed from the display after a short delay, or persistent. Because multiple routes may be displayed simultaneously, the path module automatically chooses a different color for subsequent path displays. A small control panel provides a means to change the persistence and color of displayed routes.

In the following sections, we describe both the Tcl and C code for the path module to provide a concrete example of the ease with which modules can be created.

- Simulator-Display Interface
- Implementation of the Path Module in C
- Implementation of the Path Module in Tcl

Next: Simulator-Display Interface Up: An Extensible Remote Graphical Previous: Design Issues for the