Optimizing a CORBA Inter-ORB Protocol (IIOP) Engine for Minimal Footprint Embedded Multimedia Systems

To support the quality of service (QoS) requirements of embedded multimedia applications, such as real-time audio and video, electronic mail and fax, and Internet telephony, off-theshelf middleware like CORBA must be flexible, efficient, and predictable. Moreover, stringent memory constraints imposed by embedded system hardware necessitates a minimal footprint for middleware that supports multimedia applications. This paper provides three contributions towards developing efficient ORB middleware to support embedded multimedia applications. First, we describe the optimization principle patterns used to develop a timeand space-efficient CORBA Inter-ORB Protocol (IIOP) interpreter for TAO, which is our high-performance, real-time ORB. Second, we describe the optimizations applied to TAO’s IDL compiler to generate efficient and small stubs/skeletons used in TAO’s IIOP protocol engine. Third, we empirically compare the performance and memory footprint of interpretive (de)marshaling versus compiled (de)marshaling for a wide range of IDL data types. Applying our optimization principle patterns to TAO’s IIOP protocol engine improved its interpretive (de)marshaling performance to the point where it is now comparable to the performance of compiled (de)marshaling. Moreover, our IDL compiler optimizations generate interpreted stubs/skeletons whose footprint is substantially smaller than compiled stubs/skeletons. Our results illustrate that careful application of optimization principle patterns can yield both timeand space-efficient standards-based middleware.