Middleware has become a key element in the development of distributed Cyber Physical Systems (CPS). Such systems often have strict non-functional requirements, and designers need a means to predict and manage non-functional properties. In this work, the authors present a mathematical model for the most relevant resources managed by FTT middleware architectures; namely, (1) processor, (2) memory, (3) energy and (4) network. This model can be used both off-line for simulation and designing purposes of a Cyber Physical System (CPS), or in run-time within an admission test or inside the algorithm of a specific scheduling policy executed by the middleware. In such case, the admission test is aimed at predicting whether a system fulfils the non-functional requirements or not before carrying out any modification in its execution plan at run-time.