<title>Empirical evaluation of OS endsystem support for real-time CORBA object request brokers</title>

Abstract

ABSTRACT There is increasing demand to extend Object Request Broker (ORB) middleware to support applications with stringent qualityof service (QoS) requirements. In particular, distributed multimedia applications require efficient and predictable performancefrom the middleware layer and below to deliver necessary end-to-end QoS. Although ORB middleware, such as CORBA,COM+, and Java RMI, offers transparent distribution, the QoS that it can provide depends largely on the support from theunderlying endsystems and networks.This paper provides two contributions to the study of OS endsystem support for real-time ORB middleware. First, weempirically compare and evaluate the suitability of real-time operating systems, VxWorks and LynxOS, and general-purposeoperating systems with real-time scheduling classes, Windows NT, Solaris, and Linux, for real-time ORB middleware. Whileholding the hardware and ORB constant, we systematically vary the OS and measure key platform-specific variations in latency,jitter, operation throughput, and CPU processing overhead. Second, we describe specific areas where these operating systemsmust improve so that ORB middleware will be predictable, efficient, and scalable enough to support the QoS requirements ofmultimedia applications.Our findings illustrate that general-purpose operating systems are not yet suited to meet multimedia applications withstringent QoS requirements. Our results underscore the need for a measurement-driven methodology to (1) provide an empiricalbasis for metrics that are crucial to multimedia computing and (2) to use these metrics to pinpoint and alleviate sources ofpriority inversion and non-determinism in real-time ORB endsystems.Keywords: Real-time Operating System Services, QoS-enabled 00 Middleware