The present invention relates to a method of determining when a component is schedulable in a hard real time system for processing time dependent streams of data elements. The number of components is larger than the number of available processors for processing said components and each of the components has at least one input and at least one output. The data elements are provided with time stamps and a component is schedulable when time stamped data elements from a predefined time interval of said time dependent stream of time stamped data element is available at all inputs of said component. In a specific embodiment the time stamps are points on an internally defined algorithmic time axis. The invention also relates to a hard real time system for processing time dependent streams of data elements with means for performing the above determining of scheduleability.