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The Ptolemy Project

The Ptolemy project studies modeling, simulation, and design of concurrent, real-time, embedded systems. The focus is on assembly of concurrent components. 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. A software system called Ptolemy II is being constructed in Java. The work is conducted in the Center for Hybrid and Embedded Software Systems (CHESS) in the Department of Electrical Engineering and Computer Sciences of the University of California at Berkeley. The project is directed by Prof. Edward Lee. The project is named after Claudius Ptolemaeus, the second century Greek astronomer, mathematician, and geographer.

• Tutorial: Building Ptolemy II Models Graphically
• Tutorial: Building Concurrent and Parallel Ptolemy II Models using ThreadedComposite
• Project overview paper.
• Key citation for the Ptolemy Project.

Current Research Thrusts

• Precision-timed (PRET) machines: This effort reintroduces timing into the core abstractions of computing, beginning with instruction set architectures, using configurable hardware as an experimental platform. See the white paper and the PRET workgroup.
• 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. See a relevant position paper.
• Distributed computing: Models of computation based on distributed discrete events, backtracking techniques, lifecycle management, unreliable networks, modeling of sensor networks. See recent results on distributed real-time computing, for example.
• Understandable concurrency: This effort focuses on models of concurrency in software that are more understandable and analyzable than the prevailing abstractions based on threads. See the position paper.
• Systems of systems: This effort focuses on modeling and design of large scale systems, those that include networking, database, grid computing, and information subsystems. See for example the Kepler project, which targets scientific workflows.
• Abstract semantics: Domain polymorphism, behavioral type systems, meta-modeling of semantics, comparative models of computation. See papers on semantics.
• Hybrid systems: Blended continuous and discrete dynamics, models of time, operational semantics, language design. See the paper on hybrid systems semantics.

Upcoming Events

• January 16, 2009: Eighth Biennial Ptolemy Miniconference abstracts are due.
• February 12, 2009: 2009 Berkeley EECS Annual Research Symposium (BEARS). A poster session by students, faculty, and postdoctoral scholars, in the area of embedded software and systems. Areas covered include hybrid systems, control, autonomous systems, modeling and computation, as well as tools and applications in these areas.
• April 15-16, 2009: The Eighth Biennial Ptolemy Miniconference and Ptutorial to be held in Berkeley, California.

• News

• October 14, 2008: High-Confidence Design for Distributed Embedded Systems (HCDDES) MURI Review Meeting, UC Berkeley.
• May 14, 2008: The Kepler Project has released Kepler-1.0.0. The Kepler website says:

  "The Kepler project's overall goal is to produce an open-source scientific workflow system that allows scientists to design scientific workflows and execute them efficiently using emerging Grid-based approaches to distributed computation."

  Kepler uses Ptolemy II as its execution engine.
• May 9, 2008: The Hydrant web-based workflow execution system released by Tristan King at James Cook University. Hydrant is based on Kepler, which in turn uses Ptolemy II as its execution engine.
• April 4, 2008: Ptolemy II 7.0.1 online demonstrations, documentation and software released.
• March 17, 2008: PTIDES is participating in the Google Summer of Code!
• March 1, 2008: HSBC has joined CHESS. The Ptolemy Project will be looking into distributed systems using Programming Temporally Integrated Distributed Embedded Systems (PTIDES).
• November 9, 2007: Lockheed Martin Advanced Technology Laboratories (ATL) has joined CHESS. The Ptolemy Project is participating in the NAOMI project, whose object is to explore how the precision of multiple domain specific modeling languages can be leveraged, leading to more accurate and complete models.
• July 19, 2007: Recito Designer 1.0 Beta Released. Recito, developed by SP-Process, is based on Ptolemy II. Recito adds support of data access and manipulation (database, XML dataflow), reports creation, document management and model remote execution.
• February 12-13, 2007: The Seventh Biennial Ptolemy Miniconference and Ptutorial was held in Berkeley, California.
• February 12, 2007: Professor Lee was awarded a contract from the US Army Research Laboratory to do research in Scalable Systems of Systems.
• February 9, 2007: Viptos 1.0.2 source code released. Viptos is an interface between TinyOS and Ptolemy II. TinyOS is an event-driven operating system designed for sensor network nodes that have very limited resources (e.g., 8K bytes of program memory, 512 bytes of RAM). TinyOS, is used, for example, on the Berkeley MICA motes, which are small wireless sensor nodes.
• February 4, 2007: Ptolemy II 6.0.2 online demonstrations, documentation and software released.
• January 14, 2007: Ptplot 5.6 released.
• October 2, 2006: Ptolemy II 6.0.alpha online demonstrations, documentation and software released.
• September 12, 2006: 2007 Research Summaries have been posted.
• June 2, 2006: The The Kepler Project has made Kepler-1.0.0beta1 available. Kepler is based on Ptolemy II and extends it for easier use by scientists in biology, ecology and geology for use with scientific workflows.
• May 8, 2006: The May 2006 IEEE Computer Magazine contains a cover feature by Edward A. Lee: "The Problem with Threads"

  For concurrent programming to become mainstream, we must discard threads as a programming model. Nondeterminism should be judiciously and carefully introduced where needed, and it should be explicit in programs.

• May 7, 2006: The Ptolemy II Bugzilla Bughandler has been revitalized. Also, CVS checkin email has been enabled.
• November 1, 2005: Viptos 5.1-alpha source code released.
• October 7, 2005: HyVisual 5.0.1 standalone installer released. Hybrid systems are systems with continuous-time dynamics, discrete events, and discrete mode changes. HyVisual is a visual editor and simulator for hierarchical hybrid systems. This is a bug fix release only, no new features were added.
• October 5, 2005: Ptolemy II 5.0.1 released. This is a bug fix release only, no new features were added. See the Ptolemy II 5.0.1 page for details.
• July 28, 2005: Ptplot 5.5 released.
• July 21, 2005: Ptolemy II 5.0 online demonstrations, documentation and software released.
• The Sixth Biennial Ptolemy Miniconference was held on May 12, 2005 on the UC Berkeley Campus. This year, we invited the Kepler community to jointly organize the conference, under the leadership of Bertram Ludaescher, and to give presentations and posters. Kepler is a cross-project collaboration to develop open source tools for Scientific Workflows and is currently based on the Ptolemy II system for heterogeneous concurrent modeling and design. We also invited David Bacon from IBM to give an invited talk on real-time Java. David is one of the world's top experts in this area.
• March 4, 2005: HyVisual 5.0-alpha released.
• August 4, 2004: Ptolemy II 4.0.1 online demonstrations, documentation and software released.
• August 8, 2004: Tobin Fricke wrote "An ode to the 'Exec' actor"
• August 4, 2004: VisualSense 4.0.1 Visual editor and simulator for wireless sensor network system released.
• April 25, 2004: galsC alpha release was made available. galsC is a language and compiler for use with the TinyGALS programming model, which uses TinyOS as the underlying component model.
• February 27, 2004: Chess Open house Donald O. Pederson Center, 5th Floor, Cory Hall, UC Berkeley held in association with BEARS.
• January 26, 2004: Kepler: A System for Scientific Workflows, is a cross-project collaboration to develop open source tools for Scientific Workflows and is currently based on the Ptolemy II system for heterogeneous concurrent modeling and design.
• December 30, 2003: Professor Edward A. Lee was interviewed on ABC TV News about Soft Walls. A few days later, there was a Slashdot discussion.
• December 3, 2003: A review for NSF was held to report on the first year of our NSF/ITR project, which is joint with Vanderbilt University and the University of Memphis.
• September 25, 2003: Ptplot 5.3 released.
• August 21, 2003: Ptolemy II 3.0.2 online demonstrations, documentation and software released.
• August 8, 2003: The Summer Undergraduate Program in Engineering Research at Berkeley - Information Technology (SUPERB-IT) took place from June 16-August 8 2003. The students developed many innovative extensions for Ptolemy II - Project Papers and Posters
• July 29, 2003: The 2003 2nd Quarter MoBIES Quarterly report (plain text) is now available.
• May 9, 2003: The Fifth Biennial Ptolemy Miniconference was held with 85 attendees.
• September 27, 2002: Professor Edward A. Lee and his group will be participating in the Center for Hybrid and Embedded Software Systems (CHESS) project.