Ptolemy Tutorial, Part 1
Edward A. Lee

Citation
Edward A. Lee. "Ptolemy Tutorial, Part 1". Tutorial, 27, March, 2013.

Abstract
Ptolemy II is an open-source software framework supporting experimentation with actor-oriented design. Actors are software components that execute concurrently and communicate through messages sent via interconnected ports. A model is a hierarchical interconnection of actors. In Ptolemy II, the semantics of a model is not determined by the framework, but rather by a software component in the model called a director, which implements a model of computation. The Ptolemy Project has developed directors supporting process networks (PN), discrete-events (DE), dataflow (SDF), synchronous/reactive (SR), rendezvous-based models, 3-D visualization, and continuous-time models. Each level of the hierarchy in a model can have its own director, and distinct directors can be composed hierarchically. A major emphasis of the project has been on understanding the heterogeneous combinations of models of computation realized by these directors. Directors can be combined hierarchically with state machines to make modal models. A hierarchical combination of continuous-time models with state machines yields hybrid systems; a combination of synchronous/reactive with state machines yields StateCharts (the Ptolemy II variant is close to SyncCharts). Ptolemy II has been under development since 1996; it is a successor to Ptolemy Classic, which was developed since 1990. The core of Ptolemy II is a collection of Java classes and packages, layered to provide increasingly specific capabilities. The kernel supports an abstract syntax, a hierarchical structure of entities with ports and interconnections. A graphical editor called Vergil supports visual editing of this abstract syntax. An XML concrete syntax called MoML provides a persistent file format for the models. Various specialized tools have been created from this framework, including HyVisual (for hybrid systems modeling), Kepler (for scientific workflows), VisualSense (for modeling and simulation of wireless networks), Viptos (for sensor network design), and some commercial products. Key parts of the infrastructure include an actor abstract semantics, which enables the interoperability of distinct models of computation with a well-defined semantics; a model of time (specifically, super-dense time, which enables interaction of continuous dynamics and imperative logic); and a sophisticated type system supporting type checking, type inference, and polymorphism. The type system has recently been extended to support user-defined ontologies. Various experiments with synthesis of implementation code and abstractions for verification are included in the project.

Electronic downloads

Internal. This publication has been marked by the author for TerraSwarm-only distribution, so electronic downloads are not available without logging in.

Citation formats

• HTML

  Edward A. Lee. <a
  href="http://www.terraswarm.org/pubs/46.html"
  ><i>Ptolemy Tutorial, Part 1</i></a>,
  Tutorial,  27, March, 2013.

• Plain text

  Edward A. Lee. "Ptolemy Tutorial, Part 1".
  Tutorial,  27, March, 2013.

• BibTeX

  @tutorial{Lee13_PtolemyTutorialPart1,
      author = {Edward A. Lee},
      title = {Ptolemy Tutorial, Part 1},
      day = {27},
      month = {March},
      year = {2013},
      abstract = {Ptolemy II is an open-source software framework
                supporting experimentation with actor-oriented
                design. Actors are software components that
                execute concurrently and communicate through
                messages sent via interconnected ports. A model is
                a hierarchical interconnection of actors. In
                Ptolemy II, the semantics of a model is not
                determined by the framework, but rather by a
                software component in the model called a director,
                which implements a model of computation. The
                Ptolemy Project has developed directors supporting
                process networks (PN), discrete-events (DE),
                dataflow (SDF), synchronous/reactive (SR),
                rendezvous-based models, 3-D visualization, and
                continuous-time models. Each level of the
                hierarchy in a model can have its own director,
                and distinct directors can be composed
                hierarchically. A major emphasis of the project
                has been on understanding the heterogeneous
                combinations of models of computation realized by
                these directors. Directors can be combined
                hierarchically with state machines to make modal
                models. A hierarchical combination of
                continuous-time models with state machines yields
                hybrid systems; a combination of
                synchronous/reactive with state machines yields
                StateCharts (the Ptolemy II variant is close to
                SyncCharts). Ptolemy II has been under development
                since 1996; it is a successor to Ptolemy Classic,
                which was developed since 1990. The core of
                Ptolemy II is a collection of Java classes and
                packages, layered to provide increasingly specific
                capabilities. The kernel supports an abstract
                syntax, a hierarchical structure of entities with
                ports and interconnections. A graphical editor
                called Vergil supports visual editing of this
                abstract syntax. An XML concrete syntax called
                MoML provides a persistent file format for the
                models. Various specialized tools have been
                created from this framework, including HyVisual
                (for hybrid systems modeling), Kepler (for
                scientific workflows), VisualSense (for modeling
                and simulation of wireless networks), Viptos (for
                sensor network design), and some commercial
                products. Key parts of the infrastructure include
                an actor abstract semantics, which enables the
                interoperability of distinct models of computation
                with a well-defined semantics; a model of time
                (specifically, super-dense time, which enables
                interaction of continuous dynamics and imperative
                logic); and a sophisticated type system supporting
                type checking, type inference, and polymorphism.
                The type system has recently been extended to
                support user-defined ontologies. Various
                experiments with synthesis of implementation code
                and abstractions for verification are included in
                the project.},
      URL = {http://terraswarm.org/pubs/46.html}
  }
  

Posted by Paul Lim on 8 Apr 2013.