November 22 – 27 , 2009, Dagstuhl Seminar 09481



Albert Benveniste (INRIA Rennes – Bretagne Atlantique, FR)
Stephen A. Edwards (Columbia University – New York, US)
Edward A. Lee (University of California – Berkeley, US)
Klaus Schneider (TU Kaiserslautern, DE)
Reinhard von Hanxleden (Universität Kiel, DE)

The Dagstuhl Foundation gratefully acknowledges the donation from:

  •   Artist - Network of Excellence on Embedded Systems Design

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List of Participants
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Synchronous languages have been designed to allow the unambiguous description of reactive, embedded real-time systems. The common foundation for these languages is the synchrony hypothesis, which treats computations as being logically instantaneous. This abstraction enables functionality and real-time characteristics to be treated separately, facilitating the design of complex embedded systems. Digital hardware has long been designed using the synchronous paradigm; our synchronous languages were devised largely independently and have placed the technique on a much firmer mathematical foundation.

Feedback from the user base and the continuously growing complexity of applications still pose new challenges, such as the sound integration of synchronous and asynchronous, event- and time-triggered, or discrete and continuous systems. This seminar aims to address these challenges, building on a strong and active community and expanding its scope into relevant related fields. This year’s workshop includes researchers in model-based design, embedded real-time systems, mixed system modeling, models of computation, and distributed systems.

The seminar was successful in bringing together researchers and practitioners of synchronous programming, and furthermore in reaching out to relevant related areas. With a record participation in this year’s SYNCHRON workshop of more than 50 participants and a broad range of topics discussed, the aims seem to have been well-met. The program of the seminar was composed of around 36 presentations, all of which included extensive technical discussions. The fields covered included synchronous semantics, modeling languages, verification, heterogeneous and distributed systems, hardware/software integration, reactive processing, timing analyses, application experience reports, and industrial requirements. The discussion identified and collected specific needs for future topics, in particular the integration of different models of computation.

The SYNCHRON workshop constitutes the only yearly meeting place for the researchers in this exciting field. The workshops on Synchronous Languages started in 1993 at Schloss Dagstuhl. Since then, the workshop has evolved significantly in its sixteen years of existence. One obvious change is the citizenship of its attendees, which has shifted from being largely French to being truly world-wide. But the biggest change is in its scope, which has grown to expand many languages and techniques that are not classically synchronous but have been substantially influenced by the synchronous languages’ attention to timing, mathematical rigor, and parallelism. Also, while many of the most senior synchronous language researchers are still active, many younger researchers have also entered the fray and taken the field in new directions. We look forward to seeing where they take us next.

Dagstuhl Seminar Series


  • Modelling / Simulation
  • Programming Languages / Compiler
  • Semantics / Formal Methods
  • Verification / Logic


  • Synchronous languages
  • Safety-critical real-time systems
  • Model-based design
  • Discrete and hybrid systems
  • Combining synchronous and asynchronous models
  • Formally consistent subsetting of UML
  • High-level hardware modeling and synthesis
  • Compilation and code synthesis for embedded systems
  • Visualisation of complex systems
  • Simulation
  • Verification and testing tools
  • Execution time analysis for synchronous programs
  • Industrial experience reports


In the series Dagstuhl Reports each Dagstuhl Seminar and Dagstuhl Perspectives Workshop is documented. The seminar organizers, in cooperation with the collector, prepare a report that includes contributions from the participants' talks together with a summary of the seminar.


Download overview leaflet (PDF).

Dagstuhl's Impact

Please inform us when a publication was published as a result from your seminar. These publications are listed in the category Dagstuhl's Impact and are presented on a special shelf on the ground floor of the library.


Furthermore, a comprehensive peer-reviewed collection of research papers can be published in the series Dagstuhl Follow-Ups.