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Stavros Tripakis - One of the best experts on this subject based on the ideXlab platform.
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a modular formal semantics for Ptolemy
Mathematical Structures in Computer Science, 2013Co-Authors: Stavros Tripakis, Christos Stergiou, Chris ShaverAbstract:Abstract : Ptolemy is an open-source and extensible modeling and simulation framework. It offers heterogeneous modeling capabilities by allowing different models of computation, both untimed and timed, to be composed hierarchically in an arbitrary fashion. This paper proposes a formal semantics for Ptolemy which is modular, in the sense that atomic actors and their compositions are treated in a unified way. In particular, all actors conform to an executable interface that contains four functions: fire (produce outputs given current state and inputs), postfire (update state instantaneously), deadline (how much time the actor is willing to let elapse) and time-update (update state with passage of time). Composite actors are obtained from composition operators that in Ptolemy are called directors. Different directors realize different models of computation. This paper defines formally the directors for the following models of computation: Synchronous-Reactive, Discrete Event, Continuous Time, Process Networks, and Modal Models.
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verifying hierarchical Ptolemy ii discrete event models using real time maude
Science of Computer Programming, 2012Co-Authors: Peter Csaba Olveczky, Thomas Huining Feng, Stavros TripakisAbstract:This paper defines a real-time rewriting logic semantics for a significant subset of Ptolemy II discrete-event models. This is a challenging task, since such models combine a synchronous fixed-point semantics with hierarchical structure, explicit time, and a rich expression language. The code generation features of Ptolemy II have been leveraged to automatically synthesize a Real-Time Maude verification model from a Ptolemy II design model, and to integrate Real-Time Maude verification of the synthesized model into Ptolemy II. This enables a model-engineering process that combines the convenience of Ptolemy II DE modeling and simulation with formal verification in Real-Time Maude. We illustrate such formal verification of Ptolemy II models with three case studies.
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An Introduction to the Pthales Domain of Ptolemy II
2011Co-Authors: Remi Barrere, Eric Lenormand, Christopher Shaver, Stavros TripakisAbstract:Abstract : This is an introduction to Pthales, one of the domains implemented in Ptolemy II. The semantics and behavior of Pthales are derived from SpearDE, a co-design environment developed by Thales, partly based on Ptolemy Classic. SpearDE uses a multidimensional synchronous dataflow (MDSDF) model of computation (MoC) based on the ArrayOL language. The main motivations for building Pthales have been the following: First, to extend the SpearDE MoC. The MoC realized by SpearDE supports multidimensional signal processing algorithms with relatively static structure. Second, to integrate the Pthales domain within the rest of the Ptolemy II domains.
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exploring models of computation with Ptolemy ii
International Conference on Hardware Software Codesign and System Synthesis, 2010Co-Authors: Christopher Brooks, Stavros TripakisAbstract: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. Ptolemy II takes a component view of design, in that models are constructed as a set of interacting components. A model of computation governs the semantics of the interaction, and thus imposes an execution-time discipline. Ptolemy II has implementations of many models of computation including Synchronous Data Flow, Kahn Process Networks, Discrete Event, Continuous Time, Synchronous/Reactive and Modal Model. This hands-on tutorial explores how these models of computation are implemented in Ptolemy II and how to create new models of computation such as a "non-dogmatic" Process Networks example and a left-to-right execution policy example.
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modal models in Ptolemy
Equation-Based Object-Oriented Modeling Languages and Tools, 2010Co-Authors: Stavros TripakisAbstract:Ptolemy is an open-source and extensible modeling and simulation framework. It offers heterogeneous modeling capabilities by allowing different models of computation to be composed hierarchically in an arbitrary fashion. This paper describes modal models, which allow to hierarchically compose finite-state machines with other models of computation, both untimed and timed. The semantics of modal models in Ptolemy are defined in a modular manner.
Christopher Brooks - One of the best experts on this subject based on the ideXlab platform.
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introducing triquetrum a possible future for kepler and Ptolemy ii
International Conference on Conceptual Structures, 2016Co-Authors: Christopher Brooks, Jay Jay BillingsAbstract:Abstract Triquetrum is an open platform for managing and executing scientific workflows that is under development as an Eclipse project. Both Triquetrum and Kepler use Ptolemy II as their execution engine. Triquetrum presents opportunities and risks for the Kepler community. The opportunities include a possibly larger community for interaction and a path for Kepler to move from Kepler's one-off ant-based build environment towards a more common Open Services Gateway initiative (OSGi)-based environment and a way to maintain a stable Ptolemy II core. The risks include the fact that Triquetrum is a fork of Ptolemy II that would result in package name changes and other possible changes. In addition, Triquetrum is licensed under the Eclipse Public License v1.0, which includes a patent clause that could conflict with the University of California patent clause. This paper describes these opportunities and risks.
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Ptolemy coding style
2014Co-Authors: Christopher BrooksAbstract:Abstract : Collaborative software projects benefit when participants read code created by other participants. The objective of a coding style is to reduce the fatigue induced by unimportant formatting differences and differences in naming conventions. Although individual programmers will undoubtedly have preferences and habits that differ from the recommendations here, the benefits that flow from following these recommendations far outweigh the inconveniences. Published papers in journals are subject to sim lar stylistic and layout constraints, so such constraints are not new to the academic community. This document describes the coding style used in Ptolemy II, a package with 550K lines of Java and 160 contributing programmers that has been under development since 1996.
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exploring models of computation with Ptolemy ii
International Conference on Hardware Software Codesign and System Synthesis, 2010Co-Authors: Christopher Brooks, Stavros TripakisAbstract: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. Ptolemy II takes a component view of design, in that models are constructed as a set of interacting components. A model of computation governs the semantics of the interaction, and thus imposes an execution-time discipline. Ptolemy II has implementations of many models of computation including Synchronous Data Flow, Kahn Process Networks, Discrete Event, Continuous Time, Synchronous/Reactive and Modal Model. This hands-on tutorial explores how these models of computation are implemented in Ptolemy II and how to create new models of computation such as a "non-dogmatic" Process Networks example and a left-to-right execution policy example.
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heterogeneous concurrent modeling and design in java volume 3 Ptolemy ii domains
2008Co-Authors: Shuvra S Bhattacharyya, Man Kit Leung, Christopher Brooks, Stephen Neuendorffer, Elaine Cheong, John Davis, Mudit Goel, Bart Kienhuis, Lukito Muliadi, John ReekieAbstract:Abstract : This volume describes Ptolemy II domains. The domains implement models of computation, which are summarized in chapter 1. Most of these models of computation can be viewed as a framework for component- based design, where the framework defines the interaction mechanism between the components. Some of the domains (CSP, Rendezvous, DDE, and PN) are thread-oriented, meaning that the components implement Java threads. These can be viewed, therefore, as abstractions upon which to build threaded Java programs. These abstractions are much easier to use (much higher level) than the raw threads and monitors of Java. Others (CT, DE, SDF) of the domains implement their own scheduling between actors, rather than relying on threads. This usually results in much more efficient execution. The Giotto domain, which addresses real-time computation, is not threaded, but has concurrency features similar to threaded domains. The FSM domain is in a category by itself, since in it, the components are not producers and consumers of data, but rather are states. The non-threaded domains are described first, followed by FSM and Giotto, then the threaded domains followed by two newer domains, HDF and DDF. Volume 1 is an introduction to Ptolemy II, including tutorials on use of the software, and volume 2 describes the Ptolemy II software architecture.
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heterogeneous concurrent modeling and design in java volume 1 introduction to Ptolemy ii
2008Co-Authors: Christopher Brooks, Stephen Neuendorffer, Yang Zhao, Haiyang Zheng, Shuvra S Bhattacharyya, Elaine Cheong, John Davis, Mudit Goel, Bart Kienhuis, Man Kit LeungAbstract:Abstract : This volume describes how to construct Ptolemy II models for web-based modeling or building applications. The first chapter includes an overview of Ptolemy II software, and a brief description of each of the models of computation that have been implemented. It describes the package structure of the software, and includes as an appendix a brief tutorial on UML notation, which is used throughout the documentation to explain the structure of the software. The second chapter is a tutorial on building models using Vergil, a graphical user interface where models are built pictorially. The third chapter discusses the Ptolemy II expression language, which is used to set parameter values. The next chapter gives an overview of actor libraries. These three chapters, plus one of the domain chapters, will be sufficient for users to start building interesting models in the selected domain. The fifth chapter gives a tutorial on designing actors in Java. The sixth chapter describes the Ptolemy coding style, The seventh chapter explains MoML, the XML schema used by Vergil to store models. And the eighth chapter, the final one in this part, explains how to construct custom applets. Volume 2 describes the software architecture of Ptolemy II, and volume 3 describes the domains, each of which implements a model of computation.
Peter Csaba Olveczky - One of the best experts on this subject based on the ideXlab platform.
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verifying hierarchical Ptolemy ii discrete event models using real time maude
Science of Computer Programming, 2012Co-Authors: Peter Csaba Olveczky, Thomas Huining Feng, Stavros TripakisAbstract:This paper defines a real-time rewriting logic semantics for a significant subset of Ptolemy II discrete-event models. This is a challenging task, since such models combine a synchronous fixed-point semantics with hierarchical structure, explicit time, and a rich expression language. The code generation features of Ptolemy II have been leveraged to automatically synthesize a Real-Time Maude verification model from a Ptolemy II design model, and to integrate Real-Time Maude verification of the synthesized model into Ptolemy II. This enables a model-engineering process that combines the convenience of Ptolemy II DE modeling and simulation with formal verification in Real-Time Maude. We illustrate such formal verification of Ptolemy II models with three case studies.
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extending the real time maude semantics of Ptolemy to hierarchical de models
Electronic Proceedings in Theoretical Computer Science, 2010Co-Authors: Peter Csaba OlveczkyAbstract:This paper extends our Real-Time Maude formalization of the semantics of flat Ptolemy II discreteevent (DE) models to hierarchical models, including modal models. This is a challenging task that requires combining synchronous fixed-point computations with hierarchical structure. The synthesis of a Real-Time Maude verification model from a Ptolemy II DE model, and the formal verification of the synthesized model in Real-Time Maude, have been integrated into Ptolemy II, enabling a modelengineering process that combines the convenience of Ptolemy II DE modeling and simulation with formal verification in Real-Time Maude.
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verifying Ptolemy ii discrete event models using real time maude
International Conference on Formal Engineering Methods, 2009Co-Authors: Peter Csaba Olveczky, Thomas Huining Feng, Stavros TripakisAbstract:This paper shows how Ptolemy II discrete-event (DE) models can be formally analyzed using Real-Time Maude. We formalize in Real-Time Maude the semantics of a subset of hierarchical Ptolemy II DE models, and explain how the code generation infrastructure of Ptolemy II has been used to automatically synthesize a Real-Time Maude verification model from a Ptolemy II design model. This enables a model-engineering process that combines the convenience of Ptolemy II DE modeling and simulation with formal verification in Real-Time Maude.
Yang Zhao - One of the best experts on this subject based on the ideXlab platform.
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heterogeneous concurrent modeling and design in java volume 1 introduction to Ptolemy ii
2008Co-Authors: Christopher Brooks, Stephen Neuendorffer, Yang Zhao, Haiyang Zheng, Shuvra S Bhattacharyya, Elaine Cheong, John Davis, Mudit Goel, Bart Kienhuis, Man Kit LeungAbstract:Abstract : This volume describes how to construct Ptolemy II models for web-based modeling or building applications. The first chapter includes an overview of Ptolemy II software, and a brief description of each of the models of computation that have been implemented. It describes the package structure of the software, and includes as an appendix a brief tutorial on UML notation, which is used throughout the documentation to explain the structure of the software. The second chapter is a tutorial on building models using Vergil, a graphical user interface where models are built pictorially. The third chapter discusses the Ptolemy II expression language, which is used to set parameter values. The next chapter gives an overview of actor libraries. These three chapters, plus one of the domain chapters, will be sufficient for users to start building interesting models in the selected domain. The fifth chapter gives a tutorial on designing actors in Java. The sixth chapter describes the Ptolemy coding style, The seventh chapter explains MoML, the XML schema used by Vergil to store models. And the eighth chapter, the final one in this part, explains how to construct custom applets. Volume 2 describes the software architecture of Ptolemy II, and volume 3 describes the domains, each of which implements a model of computation.
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heterogeneous concurrent modeling and design in java volume 2 Ptolemy ii software architecture
2008Co-Authors: Christopher Brooks, Stephen Neuendorffer, Yang Zhao, Haiyang Zheng, Shuvra S Bhattacharyya, Elaine Cheong, John Davis, Mudit Goel, Bart Kienhuis, Man Kit LeungAbstract:Abstract : This volume describes the software architecture of Ptolemy II. The first chapter covers the kernel package, which provides a set of Java classes supporting clustered graph topologies for models. Cluster graphs provide a very general abstract syntax for component-based modeling, without assuming or imposing any semantics on the models. The actor package begins to add semantics by providing basic infrastructure for data transport between components. The data package provides classes to encapsulate the data that is transported. It also provides an extensible type system and an interpreted expression language. The graph package provides graph-theoretic algorithms that are used in the type system and by schedulers in the individual domains. The model transformation package provides a mechanism to systematically transform models by means of graph rewriting. The plot package provides a visual data plotting utility that is used in many of the applets and applications. The codegen package is a templated based code generator similar to the Ptolemy Classic code generators. The copernicus package is a code generator that performs static analysis on Java class files to produce smaller, faster executable models. Volume 1 gives an introduction to Ptolemy II, including tutorials on the use of the software, and volume 3 describes the domains, each of which implements a model of computation.
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viptos a graphical development and simulation environment for tinyos based wireless sensor networks
International Conference on Embedded Networked Sensor Systems, 2005Co-Authors: Elaine Cheong, Edward A Lee, Yang ZhaoAbstract:We are announcing the first release of Viptos (Visual Ptolemy and TinyOS), an integrated graphical development and simulation environment for TinyOS-based wireless sensor networks. Viptos allows developers to create block and arrow diagrams to construct TinyOS programs from any standard library of nesC/TinyOS components. The tool automatically transforms the diagram into a nesC program that can be compiled and downloaded from within the graphical environment onto any TinyOS-supported target hardware. In particular, Viptos includes the full capabilities of VisualSense [1], which can model communication channels, networks, and non-TinyOS nodes. This release of Viptos is compatible with nesC 1.2 and includes tools to harvest existing TinyOS components and applications and convert them into a format that can be displayed as block (and arrow) diagrams and simulated.Viptos is based on TOSSIM and Ptolemy II. TOSSIM is an interrupt-level simulator for TinyOS programs. It runs actual TinyOS code but provides software replacements for the simulated hardware and models network interaction at the bit or packet level. Ptolemy II is a graphical software system for modeling, simulation, and design of concurrent, real-time, embedded systems. Ptolemy II focuses on assembly of concurrent components with well-defined models of computation that govern the interaction between components. VisualSense is a Ptolemy II environment for modeling and simulation of wireless sensor networks at the network level.Viptos provides a bridge between VisualSense and TOSSIM by providing interrupt-level simulation of actual TinyOS programs, with packet-level simulation of the network, while allowing the developer to use other models of computation available in Ptolemy II for modeling various parts of the system. While TOSSIM only allows simulation of homogeneous networks where each node runs the same program, Viptos supports simulation of heterogeneous networks where each node may run a different program. Viptos simulations may also include non-TinyOS-based wireless nodes. The developer can easily switch to different channel models and change other parts of the simulated environment, such as creating models to generate simulated traffic on the wireless network.Viptos inherits the actor-oriented modeling environment of Ptolemy II, which allows the developer to use different models of computation at each level of simulation. At the lowest level, Viptos uses the discrete-event scheduler of TOSSIM to model the interaction between the CPU and TinyOS code that runs on it. At the next highest level, Viptos uses the discrete-event scheduler of Ptolemy II to model interaction with mote hardware, such as the radio and sensors. This level is then embedded within VisualSense to allow modeling of the wireless channels to simulate packet loss, corruption, delay, etc. The user can also model and simulate other aspects of the physical environment including those detected by the sensors (e.g., light, temperature, etc.), terrain, etc.At IPSN in April 2005, we demonstrated a pre-release developmental version of Viptos with two simple applications. The first was a single node sensing application that displayed the value of the light sensor on the LEDs. The second was a two node send and receive application that transmitted the value of the light sensor on the first node to the second node. This release version of Viptos supports more sophisticated applications, such as multi-node routing, and demonstrates some of the more advanced features described in this abstract.
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modeling of sensor nets in Ptolemy ii
Information Processing in Sensor Networks, 2004Co-Authors: Philip J Baldwin, Sanjeev Kohli, Yang ZhaoAbstract:This paper describes a modeling and simulation framework called VisualSense for wireless sensor networks that builds on and leverages Ptolemy II. This framework supports actor-oriented definition of sensor nodes, wireless communication channels, physical media such as acoustic channels, and wired subsystems. The software architecture consists of a set of base classes for defining channels and sensor nodes, a library of subclasses that provide certain specific channel models and node models, and an extensible visualization framework. Custom nodes can be defined by subclassing the base classes and defining the behavior in Java or by creating composite models using any of several Ptolemy II modeling environments. Custom channels can be defined by subclassing the WirelessChannel base class and by attaching functionality defined in Ptolemy II models.
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IPSN - Modeling of sensor nets in Ptolemy II
Proceedings of the third international symposium on Information processing in sensor networks - IPSN'04, 2004Co-Authors: Philip J Baldwin, Sanjeev Kohli, Yang ZhaoAbstract:This paper describes a modeling and simulation framework called VisualSense for wireless sensor networks that builds on and leverages Ptolemy II. This framework supports actor-oriented definition of sensor nodes, wireless communication channels, physical media such as acoustic channels, and wired subsystems. The software architecture consists of a set of base classes for defining channels and sensor nodes, a library of subclasses that provide certain specific channel models and node models, and an extensible visualization framework. Custom nodes can be defined by subclassing the base classes and defining the behavior in Java or by creating composite models using any of several Ptolemy II modeling environments. Custom channels can be defined by subclassing the WirelessChannel base class and by attaching functionality defined in Ptolemy II models.
T. Miyazaki - One of the best experts on this subject based on the ideXlab platform.
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Code generation by using integer-controlled dataflow graph
1997 IEEE International Conference on Acoustics Speech and Signal Processing, 1997Co-Authors: T. MiyazakiAbstract:Integer-Controlled Dataflow (IDF) and its code generation applications in Ptolemy are presented. In IDF graphs, which specify data processing systems, data token flow is controlled by integer control tokens and states of actors at run-time. The firing order of actors (schedule) is determined at compile-time, however, the actors are conditionally activated at run-time. This static schedule contributes to effective simulation of systems. IDF supports code generation. This enables code generation from program graphs that include conditional jumps, loops and repetitions, and greatly improves the practical usability of the program synthesis in Ptolemy.
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ICASSP - Code generation by using integer-controlled dataflow graph
1997 IEEE International Conference on Acoustics Speech and Signal Processing, 1997Co-Authors: T. MiyazakiAbstract:Integer-Controlled Dataflow (IDF) and its code generation applications in Ptolemy are presented. In IDF graphs, which specify data processing systems, data token flow is controlled by integer control tokens and states of actors at run-time. The firing order of actors (schedule) is determined at compile-time, however, the actors are conditionally activated at run-time. This static schedule contributes to effective simulation of systems. IDF supports code generation. This enables code generation from program graphs that include conditional jumps, loops and repetitions, and greatly improves the practical usability of the program synthesis in Ptolemy.
