When focusing on the system responses of process flows and devices, all simulation-related concerns should not be dealt with, but rather be handed down to some service that delivers the requested results. Furthermore, no distinction should be made with respect to the kind of procedure to invoke to get these results. More precisely, task-level applications should be liberated as far as possible from subtleties regarding the invocation of simulators, the precise format of input decks, the proper interpretation of generated files and return values, etc. To this end, the VISTA/SFC simulation environment provides a class of objects that encapsulate all evaluation tasks on the task level and establish a uniform interface between task-level modules such as optimizers, response surface models, database queries, etc.