An object-based architecture for real-time application

This paper highlights the architecture of software systems based on RTO (Real Time Objects), a concurrent, object-based programming paradigm designed to fulfill the reqquirements of real-time applications. RTO is based on objects communicating via asynchronous message-passing. An object is a ste machine evolving through a sequence of phases, each phase being defined by a mapping from expected messages to methods. Methods are not preemptable. Object are dynamically creatred as class instances. Objects with similar real-time requirements are grouped into components; different components may be allocated to different processors. Inside a component messages are dispatched according to a (possibly user-defined) control strategy. A standard strategy is based on message timestamps. An alternative control strategy supprots a virtual time concept and can be used for simulation. The RTO paradigm can be hosted by different programming languages. An RTO extension of Modula-2 has been implemented.