Evaluating CORBA Latency and Scalability Over High-Speed ATM Networks

Conventional implementations of CORBA communication middleware incur significant overhead when used for performance-sensitive applications over high-speed networks. As gigabit networks become pervasive, inefficient middleware will force programmers to continue using lowerlevel mechanisms to achieve necessary transfer rates and end-to-end latency. This is a serious problem for mission/lifecritical applications(such as real-time avionics, process control systems, and medical imaging). This paper provides two contributions to the study of CORBA performance over high-speed networks. First, we measure the latency of various types and sizes of oneway and twoway client requests using a pair of widely used implementations of two C++ implementations of CORBA – Orbix 2.1 and VisiBroker 2.0. Second, we use Orbix and VisiBroker to measure the scalability of CORBA servers in terms of the number of objects they can support efficiently. These experiments extend our previous work on CORBA performance for bandwidth-sensitive applications (such as satellite surveillance, medical imaging, and teleconferencing). Our results show that the latency for CORBA implementations is relatively high and server scalability is relatively low. Our latency experiments show that non-optimized internal buffering and presentation layer conversion overhead in CORBA implementations can cause substantial delay variance, which is unacceptable in many real-time or constrained-latency applications. Likewise, our scalability experiments reveal that neither Orbix nor VisiBroker can handle a large number of objects in a single server process. The paper concludes by outliningoptimizationswe are developing to overcome the performance limitations with existing 1This work was supported in part by NSF grant NCR-9628218. Copyright 1997 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works, must be obtained from the IEEE. Contact: Manager, Copyrights and Permissions / IEEE Service Center 445 Hoes Lane / P.O. Box 1331 Piscataway, NJ 08855-1331, USA. Telephone: + Intl. 908-562-3966. CORBA implementations.