On evaluating interaction and communication schemes for automation applications based on real-time distributed objects

This paper compares interaction and communication mechanisms used in distributed control systems, focusing on object-oriented and component-based development. The standard communication model used in distributed object oriented systems is remote method invocation. We argue that this client/server oriented model has some severe drawbacks when used in a control system where objects may have to broadcast information, spontaneously communicate environmental changes and where control autonomy is a crucial requirement. Therefore, we compare the traditional way of object invocation with a port-based scheme and the model of event channels. An application scenario from robot control is used to highlight similarities and differences among these mechanisms.