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A traditional application built around poll will have a single structure containing all active descriptors, which is passed to the kernel every time the applications goes through the central event loop. A kqueue-aware applica- tion will need to notify the kernel of any changes to the list of active descriptors, instead of passing in the entire list. This can be done either by calling kevent() for each update to the active descriptor list, or by building up a list of descriptor changes and then passing this list to the kernel the next time the event loop is called. The lat- ter approach offers better performance, as it reduces the number of. | The Design and Performance of a Real-time CORBA Event Service Timothy H. Harrison Carlos O Ryan. David L. Levine and Douglas c. Schmidt harrison coryan levine schmidt @cs.wustl.edu Department of Computer Science Washington University St. Louis MO 63130 USA This paper has been submitted to the IEEE Journal on Selected Areas in Communications special issue on Service Enabling Platforms for Networked Multimedia Systems. Abstract The CORBA Event Service provides a flexible model for asynchronous and group communication among distributed and collocated objects. However the standard CORBA Event Service specification lacks important features required by applications with real-time requirements such as low latency predictability event filtering priority and event correlation. This paper describes the design and performance of an object-oriented real-time implementation of the CORBA Event Service that is designed to meet these requirements. This paper makes four contributions to the design and performance measurement of object-oriented real-time systems. First it illustrates how to extend the CORBA Event Service so that it is suitable for real-time systems. These extensions support low latency periodic rate-based event processing and efficient event filtering and correlation. Second it describes how to develop object-oriented event dispatching and scheduling mechanisms that can provide real-time guarantees. Third it describes how to distribute the Event Service effectively and provide low latency for collocated suppliers consumers. Finally the paper presents benchmarks that empirically demonstrate the predictability low latency and high utilization of our real-time Event Service. Keywords Real-time CORBA event systems object-oriented communication frameworks. 1 Introduction There is a widespread belief in the embedded systems community that object-oriented OO techniques are not suitable for real-time systems. However many real-time application This work was funded in part .
