1. A method, in a data processing system, for controlling a fidelity of a simulation of a system, comprising: receiving a model of the system, wherein the model of the system comprises a plurality of individual components of the system; assigning fidelity values to models of the individual components of the system; assigning a required fidelity value to transactions between components in the plurality of individual components of the system; executing a simulation of the system using the model of the system and the models of the individual components of the system; and dynamically adjusting fidelity values of one or more of the models of the individual components of the system during the execution of the simulation based on the required fidelity values assigned to the transactions, wherein a first transaction sent from a sender component to a receiver component comprises a first required fidelity value, and wherein dynamically adjusting fidelity values of one or more of the models of the individual components of the system based on the required fidelity values assigned to the transactions comprises adjusting a fidelity value associated with a model of the receiver component based on the first required fidelity value of the first transaction.