Modeling and simulation techniques have enabled companies to diagnose and solve problems before any expensive prototypes are built. But with the increase in complexity of cyber physical systems, companies have to divide and conquer: they have to develop different components concurrently and they have to do business with specialized suppliers. Now it becomes harder to develop systems first time right because different teams will use different tools to build their models and the suppliers will not be willing to give away detailed models in order to protect their intellectual property. A solution is to establish a common interface that allows multiple simulation tools to talk to each other without revealing the details of the models being simulated. This is co-simulation, my main research interest.