In our previous work, we have defined a formal model for
  component-based real-time embedded systems. We use a set of
  variables to denote the amount of different kinds of resources
  needed to implement the component. The WCET of each component method
  is represented in terms of a predicate over the resource variables.
  Such a model enables therefore the flexibility the component
  specification. It can also be used to build component-based
  requirements model. In this model the concurrency and the
  schedulability analysis of component methods are left unspecified.
  These aspects are the subject of the current report. We present an
  approach for specifying concurrency and schedule invariance of the
  component-based real-time embedded systems. We show that the
  proposed model enables the schedulability analysis. We address also the way
  to use our model in development of real-time systems.

  Keywords: Component-based systems, Real-time constraints, Duration
  Calculus, Unifying Theory of Programming