Ptolemy Project

Edward A. Lee, Ilge Akkaya, Hugo Andrade¹, Steve Bako, Christopher Brooks, Janette Cardoso², Dai Bui, Yasemin Demir, Gage Eads, John Eidson, Shanna-Shaye Forbes, Soheil Ghiasi³, Tatsuaki Iwata⁴, Elizabeth Latronico⁵, Ben Lickly, Isaac Liu, Slobodan Matic, Eleftherios Matsikoudis, Minxue Pan, Jan Reineke, Dorsa Sadigh, Christopher Shaver, Charles Shelton⁶, Mary Stewart, Stavros Tripakis, Maarten Wiggers, Jia Zou and Michael Zimmer

Center for Hybrid and Embedded Software Systems, National Science Foundation 0720882 (CSR-EHS: PRET), National Science Foundation 1035672 (CPS: PTIDES), National Science Foundation 0931843 (ActionWebs), Army Research Office W911NF-07-2-0019 (SCOS), Air Force Office of Scientific Research FA9550-06-0312 (HCDDES MURI), Air Force Research Lab, Multiscale Systems Center (MuSyC), Robert Bosch GmBH, National Instruments, Thales and Toyota

The Ptolemy Project studies modeling, simulation, and design of concurrent, real-time, embedded systems. The focus is on assembly of concurrent components [1]. The key underlying principle in the project is the use of well-defined models of computation that govern the interaction between components. A major problem area being addressed is the use of heterogeneous mixtures of models of computation. Current research thrusts include:

Precision-timed (PRET) machines [2]: This effort reintroduces timing into the core abstractions of computing, beginning with instruction set architectures, using configurable hardware as an experimental platform;
Real-time software: Models of computation with time and concurrency, metaprogramming techniques, code generation and optimization, domain-specific languages, schedulability analysis, programming of sensor networks;
Distributed computing [3]: Models of computation based on distributed discrete events, backtracking techniques, lifecycle management, unreliable networks, modeling of sensor networks;
Understandable concurrency: This effort focuses on models of concurrency in software that are more understandable and analyzable than the prevailing abstractions based on threads, and more suitable for implementation on multicore architectures;
Systems of systems: This effort focuses on modeling and design of large scale systems, those that include networking, database, grid computing, and information subsystems;
Abstract semantics: Domain polymorphism, behavioral type systems, meta-modeling of semantics, comparative models of computation; and
Hybrid systems: Blended continuous and discrete dynamics, models of time, operational semantics, and language design.

Figure 1: The Ptolemy project is named after Claudius Ptolemaeus, the second century Greek astronomer, mathematician, and geographer.

[1]: Johan Eker, Jörn W. Janneck, Edward A. Lee, Jie Liu, Xiaojun Liu, Jozsef Ludvig, Stephen Neuendorffer, Sonia Sachs, Yuhong Xiong, "Taming Heterogeneity - the Ptolemy Approach," Proceedings of the IEEE, Jan 2003, Volume: 91, Issue: 1, p127-144.
[2]: S. Edwards and E. A. Lee, "The Case for the Precision Timed (PRET) Machine," UC Berkeley EECS Department Technical Report No. UCB/EECS-2006-149, November 17, 2006.
[3]: Y. Zhao, J. Liu, and E. A. Lee, "A Programming Model for Time-Synchronized Distributed Real-Time Systems," Proceedings of the 13th IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS 07), Bellevue, WA, April 3-6, 2007.

¹National Instruments
²Institut Superieur de l’Aeronatique et de l’Espace
³UC Davis
⁴Toshiba
⁵Bosch
⁶Bosch

More information: http://ptolemy.eecs.berkeley.edu