Component Composition for Embedded Systems Using Semantic AspectOriented Programming

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Component Composition for Embedded Systems Using
Semantic Aspect-Oriented Programming

• Martin Rinard
• Laboratory for Computer Science
• Massachusetts Institute of Technology
• F33615-00-C-1692

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Problem Description

• Need for improved flexibility, reliability, and
  predictability of software for embedded and
  real-time systems
• Lack of real-time support in standard languages
  and systems
• Lack of real-time memory management support in
  Java
• Lack of real-time scheduling support in Java
• Need for better support for dynamic distributed
  computations
• Need to easily integrate new devices into running
  systems
• Need for implementations that survive failures
• Need to easily compose components on different
  platforms
• Need for better understanding of distributed
  implementations
• Understand communication patterns and their
  implications
• Support for fault propagation analysis

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Objectives Technical Approach

• System Architecture
• Distributed Object-Oriented Programming
• Java shared object space
• Dynamically deployed components
• Publish/subscribe event model
• Powerful event mechanism
• Open, extensible system
• Communication via shared objects

• Object Relationship Analysis
• Goal Match Object and Computation Lifetimes
• Pointer and escape analysis for multithreaded
  programs
• Goal Capture and exploit changing roles objects
  play
• Roles change as objects move between data
  structures
• Points-to relationships determine roles
• Role specifications at method boundaries
• Supplied by programmer or dynamically discovered
• Statically verified by role analysis
• Program analysis system statically knows all
  object references

• Real-Time Java
• Region-based object allocation
• Compiler-controlled scheduling
• Compile scheduling checks into generated code,
  check for
• Asynchronous event dispatch
• Preemptive thread scheduling
• Priority ceiling and inheritance for monitors

• Interaction Analysis
• Characterizes interactions between components
• Uses roles to extract detailed object usage
  information
• Matches role changes and movements between
  components
• Matches publishers and subscribers
• Matches roles with object usage patterns
  (migrating, inherited, shared, private objects)
• Extracts failure propagation information

• Transformations
• Replace general publish/subscribe mechanism with
• Point-to-point communication (when appropriate)
• Controlled multicast (when appropriate)
• Request/response (when appropriate)
• Preemtively move or replicate objects to close
  failure vulnerability windows

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Contribution to PCES Goals

• What we provide Automated understanding of
  distributed, embedded, and real-time software
• Pointer and escape analysis
• Role analysis
• Interaction analysis
• Some envisioned uses
• Safe memory management alternatives
• Verification of safe use of region-based
  allocation
• Roles enable explicit deallocation instead of
  garbage collection
• Interaction analysis
• Understanding and validation of synchronization
  interactions
• Understanding of communication patterns
• Understanding of how failures propagate
• Validations of ABSENCE of interactions
• Transformations
• Specialized, efficient communication
  implementations
• Close windows of failure vulnerability

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Contribution to Military Applications

• Basic Contribution More Flexible, Reliable,
  Predictable Real-Time, Distributed, and Embedded
  Systems
• Implementation technology to enable use of
  standard, widely used language (Java) in military
  applications
• Compiler-controlled event and thread management
• Memory management algorithms for real-time
  systems
• Potential application areas
• Real-time monitoring and control
• Information collection and presentation
• Integrating (distributed) systems of systems

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Project Tasks and Schedule

• Real-Time Java Implementation
• Scoped Memories (Year 1)
• Threads and Events (Year 3)
• Publish/Subscribe Implementation
• Initial prototype (Year 2)
• Final version (Year 4)
• Pointer and Escape Analysis (Year 1)
• Role Analysis
• Initial design and implementation (Year 2.5)
• Final design and implementation (Year 4)
• Interaction Analysis and Transformations
• Failure propagation analysis (Year 3)
• Transformations to close windows of failure
  vulnerability (Year 4)

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Technical Progress/Accomplishments

• Implementation of Real-Time Java Scoped Memories
• Scoped memory allocation primitives
• Pointer and escape analysis for multithreaded
  programs (PPoPP 01)
• Verify correct use of scoped allocation
• Eliminate dynamic checks
• Incrementalized pointer and escape analysis (PLDI
  01)
• Initial phases of distributed surveillance
  application
• Initial JavaCar prototype 1/6 scale car with
• 233 MHz StrongARM, 32 Mbytes, running Java on
  Linux
• Camera, wireless ethernet, USB, various sensors
• Speed and steering control
• Initial role design, specification language,
  analysis

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Next Milestones

• Progress in Following Areas
• Publish/Subscribe Design and Implementation
• Realization in Java (Event class)
• Event distribution mechanism
• Shared object space mechanism
• Real-Time Java Threads and Events
• Role Design, Specification, and Analysis
• JavaCar and Surveillance Applications

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Collaborations

• Washington University
• Real-Time Java Memory Management
• Dynamic Scope Generation (Washington)
• Static Scope Verification (MIT)
• Kansas State University
• Anyone else with Real-Time Java needs
• We provide open implementation
• We provide analysis

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Technology Transfer

• Real-Time Java
• Implementation available under GNU GPL
• Anyone can download it, use it, improve it
• Real-Time Java as Infection Vector
• Integrated pointer and escape analysis
• Correctness tool for region allocation
• Enables stack allocation (reduces memory
  footprint)
• Integrated role discovery and analysis
• Dynamic discovery leads to easy initial
  experience
• Roles become central abstraction for developer
• Roles publish/subscribe system easy,
  effective distribution
• Communication and failure propagation analysis
• Useful transformations
• Dynamic deployment
• Our system serves as prototype
• Illustrates key implementation techniques
• Helps others evaluate suitability for their
  application

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Funding Profile

• Current expenditures 150,000
• Current burn rate 30,000 per month
• Burn rate will rise as project continues to ramp
  up