6.7.1 Why a GUI is not enough

Whereas the GUI provides valuable support for the interactively defining new tasks and for viewing and analyzing simulated results, it imposes some restriction on the versatility of the simulation environment.

• First of all, it requires a connection to a display, which makes it impractical for use across phone lines. Furthermore, once a task has been defined, the user might wish to leave the terminal and have the task completed autonomously. With a permanent GUI, the display has to remain active all the time, and the user cannot log out of the session without stopping the application.
• Secondly, the representation of the functional components at the GUI level, in general, cannot completely reflect all possible operations, but supports only a subset of possible applications. One can imagine to define tasks and applications that are very difficult to support on the GUI level.
• Thirdly, when intending to integrate the VISTA/SFC environment with other tools in a client-server fashion, a permanent GUI is a severe impediment for all automation tasks. For instance, when operated as a simulation server for a larger TCAD group, the GUI is provided by some client application that goes in between the user and the server process; Figure 6.9 sketches the situation.

 
Figure 6.9:   When operated as a server for other applications, VISTA/SFC is run in text-terminal mode, the GUI being provided by the client.

Therefore, emphasis has been put on completely separating the graphical user interface from the rest of the simulation environment. Both text-terminal and batch-mode operations are fully supported.