Book Chapters

Refereed Conference Publications

1. Arvind S. Krishna, Douglas C. Schmidt and Raymond Klefstad Enhancing Real-time CORBA via Real-time Java, IEEE International Conference on Distributed Computing Systems (ICDCS), Tokyo Japan, March 2004
   This paper provides the following contributions to the study of middleware for DRE applications. First we analyze the architecture of ZEN, our implementation of Real-time CORBA, identifying sources for the application of RTSJ features. Second, we describe how RTSJ features, such as scoped memory and real-time threads, can be associated with key ORB components to enhance the predictability of DRE applications using Real-time CORBA and the RTSJ. Third, we perform preliminary qualitative and quantitative analysis of predictability enhancements arising from our application of RTSJ features. Our results show that use of RTSJ features can considerably improve the predictability of DRE applications written using Real-time CORBA and Real-time Java.
2. Arvind S. Krishna, Douglas C. Schmidt, Krishna Raman and Douglas C. Schmidt Enhancing Real-time CORBA predictability and Scalability, International Symposium on Distributed Objects and Applications (DOA), Catania, Sicily, November 2003
   This paper provides the following contributions to the study of QoS-enabled middleware for DRE applications. First, we outline key Real-time CORBA implementation challenges within the ORB Core, focusing on efficient buffer allocation and collocation strategies. Second, we describe how these challenges have been addressed in ZEN, which is an implementation of Real-time CORBA that runs atop RTSJ platforms. Third, we describe how RTSJ features, such as scoped memory and no-heap real-time threads, can be applied in a real-time ORB Core to enhance the predictability of DRE applications using Real-time CORBA and the RTSJ. Our results show that carefully applied optimization strategies can enable RTSJ-based Real-time CORBA ORBs to achieve effective QoS support for a range of DRE applications.
3. Arvind S. Krishna, Douglas C. Schmidt, Raymond Klefstad and Angelo Corsaro Towardspredictable Java Object Request Brokers, IEEE Real-time Application Symposium,Washington DC, May 2003
   This paper provides the following contributions to the study of middleware for DRE applications. First, we outline the challenges present in one of the principal ORB components -- the portable object adapter (POA) -- focusing on predictable and scalable demultiplexing, object key processing, and servant lookup operations. Second, we describe how these challenges are addressed in ZEN, which is an implementation of Real-time CORBA that runs atop jRate, which is an ahead-of-time compiler that implements most of the RTSJ. Third, we qualitatively and quantitatively compare ZEN's demultiplexing strategies with those of other popular Java ORBs, including JacORB, Sun JDK ORB, and ORBacus. Our results show that ZEN and jRate incorporate the strategies necessary to enable predictability using standards-based middleware and also provide a baseline for what can be achieved by combining Real-time CORBA and RTSJ.
4. Raymond Klefstad, Arvind S. Krishna and Douglas C. Schmidt Design of a ModularCORBA Portable Object Adapter for Distributed Real-time Embedded Systems.Proceedings of the International Symposium on Distributed Objects and Applications Irvine, CA, October 2002.
   This paper discusses the design and performance of ZENs portable object adapter (POA) which is an important component in a CORBA object request broker (ORB). This paper makes the following three contributions to the study of middleware for memory-constrained DRE applications. First, it presents three alternative designs of the CORBA POA. Second, it explains how design patterns can be applied to improve the quality and performance of POA implementations. Finally, it presents empirical measurements based on the ZEN ORB showing how memory footprint can be reduced significantly while throughput is comparable to a conventional ORB implementation.