Ptolemy Project Vision

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Ptolemy Project Vision

• Edward A. Lee
• Robert S. Pepper Distinguished Professor
• Eighth Biennial Ptolemy Miniconference
• April 16, 2009
• Berkeley, CA, USA

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Cyber-Physical Systems (CPS)Where it is going

• CPS Orchestrating networked computational
  resources with physical systems.

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CPS is Multidisciplinary
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Ptolemy Project Research

• Foundations Timed computational semantics.
• Bottom up Embedded processors (PRET).
• Top down Distributed real-time systems (PTIDES).
• Holistic Scalable model-based design.

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Object Oriented vs. Actor OrientedSoftware
Components
Things happen to objects
Actors make things happen
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Timed Software Semantics
super-dense time
concurrent actor-oriented models
abstraction
s ? S N
Causal systems operating on signals are usually
naturally (Scott) continuous.
fixed-point semantics
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Results

• Papers
• 1 Lee and Matsikoudis, "The Semantics of
  Dataflow with Firing," in From Semantics to
  Computer Science Essays in memory of Gilles
  Kahn, Cambridge 2009.
• 2 Ye Zhou and Edward A. Lee. "Causality
  Interfaces for Actor Networks," ACM Trans. on
  Embedded Computing Systems, April 2008.
• 3 Liu and Lee, "CPO Semantics of Timed
  Interactive Actor Networks, Theoretical Computer
  Science 409 (1) pp.110-25, 2008..
• 4 Lee, " Application of Partial Orders to Timed
  Concurrent Systems," article in Partial order
  techniques for the analysis and synthesis of
  hybrid and embedded systems, in CDC 07.
• 5 Lee and Zheng, "Leveraging Synchronous
  Language Principles for Heterogeneous Modeling
  and Design of Embedded Systems," EMSOFT 07.
• 6 Liu, Matsikoudis, and Lee. "Modeling Timed
  Concurrent Systems," CONCUR 06.
• 7 Cataldo, Lee, Liu, Matsikoudis and Zheng "A
  Constructive Fixed-Point Theorem and the Feedback
  Semantics of Timed Systems," WODES'06
• etc. ...

• Software
• Ptolemy II realizes a number of timed concurrent
  models of computation (MoCs) with well-founded
  rigorous semantics.
• Ph.D. Theses
• 1 Haiyang Zheng, "Operational Semantics of
  Hybrid Systems," May 18, 2007.
• 2 Ye Zhou, "Interface Theories for Causality
  Analysis in Actor Networks," May 15, 2007.
• 3 Xiaojun Liu, "Semantic Foundation of the
  Tagged Signal Model," December 20, 2005.

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Ptolemy II Our Laboratory for Actor-Oriented
Models of Computation
Concurrency management supporting dynamic model
structure.
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Ptolemy Project Research

• Foundations Timed computational semantics.
• Bottom up Embedded processors (PRET).
• Top down Distributed real-time systems (PTIDES).
• Holistic Scalable model-based design.

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Bottom Up Embedded Processors

• Precision-Timed (PRET) Machines
• Make temporal behavior as important as logical
  function.
• Timing precision with performance Challenges
• Memory hierarchy (scratchpads?)
• Deep pipelines (interleaving?)
• ISAs with timing (deadline instructions?)
• Multicore (dedicated I/O real-time processors?)
• Predictable memory management (Metronome?)
• Languages with timing (discrete events? Giotto?)
• Predictable concurrency (synchronous languages?)
• Composable timed components (actor-oriented?)
• Precision networks (TTA? Time synchronization?)
• See S. Edwards and E. A. Lee, "The Case for the
  Precision Timed (PRET) Machine," in the Wild and
  Crazy Ideas Track of the Design Automation
  Conference (DAC), June 2007.

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PRET Project (Berkeley, Columbia)

• Funding from NSF, Toyota, National Instruments,
  plus cooperation with Xilinx, Synfora, and
  Tidorum
• Staffing
• Edward A. Lee (UCB PI)
• Stephen Edwards (Columbia co-PI)
• Jan Rabaey (UCB co-PI)
• John Wawrzynek (UCB co-PI)
• Christopher Brooks (Technical staff)
• Hiren Patel (postdoc)
• Hugo Andrade (NI VIF)
• Shanna-Shaye Forbes (UCB grad student)
• Sunjun Kim (Columbia grad student)
• Ben Lickly (UCB grad student)
• Isaac Liu (UCB grad student)

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Ptolemy Project Research

• Foundations Timed computational semantics.
• Bottom up Embedded processors (PRET).
• Top down Distributed real-time systems (PTIDES).
• Holistic Scalable model-based design.

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PTIDES Programming Temporally Integrated
Distributed Embedded Systems

• Distributed execution under DE semantics, with
  model time and real time bound at sensors and
  actuators.

Input time stamps are real time
Output time stamps are real time
Input time stamps are real time
Output time stamps are real time
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PTIDES Project

• Funding from NSF, Agilent, IBM, Toyota, and the
  State of California MICRO program, in cooperation
  with the University of Salzburg, Austria.
• Staffing
• Edward A. Lee (UCB PI)
• Christopher Brooks (Technical staff)
• Patricia Derler (Univ. Salzburg grad student)
• Slobodan Matic (postdoc)
• Thomas Feng (UCB grad student)
• Ben Lickly (UCB grad student)
• Stefan Resmerita (Univ. Salzburg technical staff)
• Yang Zhao (UCB grad student, Google technical
  staff)
• Jia Zou (UCB grad student)

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Ptolemy Project Research

• Foundations Timed computational semantics.
• Bottom up Embedded processors (PRET).
• Top down Distributed real-time systems (PTIDES).
• Holistic Scalable model-based design.

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Hierarchical MultimodelingHierarchical
compositionsof models of computation.
Maintaining temporal semantics across MoCs is a
main challenge.
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Multi-View ModelingDistinct and separate models
of the same system are constructed to model
different aspects of the system.
Functional model in Statecharts
Verification model in SMV
Deployment model in Ptolemy II
Functional model in Ptolemy II
This example is a test case for a collaborative
project with Lockheed-Martin
Reliability model in Excel
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Model Engineering Project

• Funding from AFRL, Army Research Office, Air
  Force Research Office, Bosch, Lockheed-Martin,
  and Thales.
• Staffing
• Edward A. Lee (UCB PI)
• Christopher Brooks (Technical staff)
• Chihong (Partrick) Cheng (TU Munich)
• Thomas Huining Feng (UCB grad student)
• Jackie Mankit Leung (UCB grad student)
• Eleftherios Matisikoudis (UCB grad student)
• Stavros Tripakis (Visiting Research Scientist)

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Addressing the Design Challenges for Cyber
Physical Systems

• Foundations Timed computational semantics.
• Abstract semantics on super-dense time
• Bottom up Make timing repeatable.
• Precision-timed (PRET) machines
• Top down Timed, concurrent components.
• Distributed real-time discrete-events (PTIDES)
• Holistic Model engineering.
• Mulimodeling, ontologies, property system,