Optimizing the Performance of the CORBA Internet Inter-ORB Protocol Over ATM

Abstract

The Internet Inter-ORB Protocol (IIOP) enables heterogeneous CORBA-compliant Object Request Brokers (ORBs) to interoperate over TCP/IP networks. The IIOP uses the Common Data Representation (CDR) transfer syntax to map CORBA Interface Definition Langauge (IDL) data types into a bi-canonical wire format. Due to the excessive marshaling/demarshaling overhead, data copying, and high-levels of function call overhead, conventional implementation of IIOP protocols yield poor performance over high-speed networks. To meet the demands of emerging distributed multimedia applications, CORBA-compliant ORBs must support both interoperable and highly efficient IIOP implementations. This paper provides two contributions to the study and design of high performance CORBA IIOP implementations. First, we precisely pinpoint the key sources of overhead in the SunSoft IIOP implementation (which is the standard reference implementation of IIOP written in C++) by measuring its performance for transferring richly-typed data over a high speed ATM network. Second, we empirically demonstrate the benefits that stem from systematically applying protocol optimizations to SunSoft IIOP. These optimizations include: optimizing for the expected case; eliminating obvious waste; replacing general purpose methods with specialized,... Read complete abstract on page 2.