Requirements and limits of a real-time transport system for distributed object computing middleware

With the advent of real-time extensions for communication middleware, new Q uality of Service (QoS) aspects have to be considered. These include specif ication of constraints, timely delivery, validation and exception handling mechanisms. For that to be accomplished modifications of the communication platforms including the transport layer are necessary. In this context we e valuate which tasks should be performed by the middleware or preferably by the transport system for the provision of real-time guarantees. Furthermore , requirements for a real-time transport system as well as an architecture for object communication within ATM networks will be introduced. Based on a developed optimised transport system for local ATM networks that is the fo undation for our realtime approach, we will present performance results. An other aspect is that deterministic operations may degrade performance. Sinc e this performance degradation can not be ignored, mechanisms for applying ATM traffic classes will be introduced to support normal operation as well as worst case scenarios. As a result this paper outlines possible gains and limits for real-time distributed object communication within pure ATM netw orks.