Implementation of multimedia systems based on a real-time extension of Estelle

Estelle is one of the standardized Formal Description Techniques for the specification of communication protocols and distributed systems. Unfortunately, Estelle is not capable of expressing real-time requirements resp. characteristics of services or protocols which are especially interesting in the context of distributed multimedia systems. Therefore, we developed an extension to Estelle called Real-Time Estelle that allows the description of real-time systems. In this paper, we first give a short introduction into Real-Time Estelle and compare it to earlier approaches to the inclusioin of real time into FDTs. In the main part, we discuss possibilities to implement such specifications in a manner guaranteeing QoS requirements by using a real-time operating system. An analysis shows that time bounds can be guaranteed not only for single Estelle module instances but also for module groups where single modules communicate asynchronously.