jacques.combaz AT imag.fr
VERIMAG
Bâtiment IMAG
700, avenue centrale
38401 Saint Martin d’Hères
FRANCE
tel: +33 4 57 42 22 10
fax: +33 4 57 42 22 22











CNRS research engineer at Verimag laboratory in the DCS team.

Topics


Real-Time

Building real-time systems requires efficient scheduling algorithms that enforce real-time constraints and optimize parameters such as latency, throughput, jitter, etc. Another issue is the definition of sufficiently expressive models and the generation of faithful implementations from these models.

Adaptivity

During my PhD, I developed fine grain QoS control techniques for multimedia applications. The goal of this work was to enforce real-time constraints (e.g. time budget) for a cyclic task using a fine grain controller that dynamically adapts the QoS parameters of the task during an execution cycle. Fine grain control combines performances of best-effort approaches usually based on average case analyses, and guarantees of safety critical approaches usually based on worst-case analyses. Experimental results for a real-time video encoder show a QoS maximization without missing the deadlines.

Embedded Applications

My work targets embedded applications. Software for embedded applications is deployed on dedicated hardware platforms that are usually tightly constrained (e.g. memory, CPU, etc.) and require specific programming methods and tools. Developing embedded applications means accommodating these contraints using highly optimized algorithms and looking for tradeoffs between the accuracy the algorithms involved and their overhead.

Current Projects


BIP

I am in charge of providing real-time implementations for BIP programs for embedded platforms. This work includes:
- the development of rigorous techniques for implementing timed BIP programs (i.e. interacting timed automata), as well as mechanisms for interfacing BIP programs with their environment (i.e. the target platform: sensors, actuators),
- the definition of an extension of the BIP language,
- a modification of the parser and the C++ code generator, and
- the development of a Real-Time BIP Engine.

Publications


Tesnim Abdellatif, Jacques Combaz, and Marc Poulhičs: Correct Implementation of Open Real-Time Systems. In Proceedings of the 37th EUROMICRO Conference on Software Engineering and Advanced Applications (SEAA 2011), Oulu, Finland, pages 57-64, August 2011.

Ananda Basu, Saddek Bensalem, Marius Bozga, Jacques Combaz, Mohamad Jaber, Thanh-Hung Nguyen, and Joseph Sifakis: Rigorous Component-Based System Design Using the BIP Framework. In IEEE Software, volume 28, pages 41-48.

Tesnim Abdellatif, Jacques Combaz and Joseph Sifakis: Model-Based Implementation of Real-Time Applications. In Proceedings of the 10th ACM International Conference on Embedded Software (EMSOFT 2010) Scottsdale, Arizona, USA. [ long version in pdf ]

Jacques Combaz and Loïc Strus: A stochastic approach for fine grain QoS control. In Proceedings of the 6th IEEE/ACM/IFIP Workshop on Embedded Systems for Real-Time Multimedia (ESTIMedia 2008) Atlanta, Georgia, USA, pages 115-120. IEEE Computer Society, October 2008. [ bib | pdf ]

Mohamad Jaber, Jacques Combaz, Loïc Strus, and Jean-Claude Fernandez: Using neural networks for quality management. In Proceedings of 13th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA 2008), Hamburg, Germany, pages 1441-1448. IEEE Computer Society, September 2008. [ bib | pdf ]

Jacques Combaz, Jean-Claude Fernandez, Joseph Sifakis, and Loïc Strus: Symbolic quality control for multimedia applications. Real-Time Systems, 40(1):1-43, October 2008. [ bib | pdf ]

Jacques Combaz, Jean-Claude Fernandez, Joseph Sifakis, and Loïc Strus: Using speed diagrams for symbolic quality management. In Proceedings of the 21th International Parallel and Distributed Processing Symposium (IPDPS 2007), Long Beach, California, USA, pages 1-8. IEEE Computer Society, March 2007. [ bib | pdf ]

Jacques Combaz: Conception de Systèmes Adaptatifs Sûrs et Optimaux. PhD thesis, Université Joseph Fourier - Grenoble I, Grenoble, France, June 2006. [ bib | pdf ]

Jacques Combaz, Jean-Claude Fernandez, Thierry Lepley, and Joseph Sifakis: QoS control for optimality and safety. In Wayne Wolf, editor, Proceedings of the 5th Conference on Embedded Software (EMSOFT 2005), Jersey City, New Jersey, USA, pages 90-99. ACM, September 2005. [ bib | pdf ]

Jacques Combaz, Jean-Claude Fernandez, Thierry Lepley, and Joseph Sifakis: Fine grain QoS control for multimedia application software. In Design, Automation and Test in Europe (DATE 2005), Munich, Germany, volume 2, pages 1038-1043. IEEE Computer Society, March 2005. [ bib | pdf ]

Miscellaneous


My Flickr personal page.