Timed Patterns: From TCOZ to Timed Automata

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Timed Patterns From TCOZ to Timed Automata
J.S. Dong, P. Hao, S.C. Qin, J. Sun National
University of Singapore Y. Wang Uppsala
University
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Outline
Outline

• Motivation
• Introduction on TCOZ and TA
• Composable Timed Patterns
• Projection from TCOZ to TA
• Case study Railway Crossing System
• Conclusion Future Work

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Motivation

• TCOZ
• Powerful notation for modeling the state, process
  and timing aspects of complex real-time systems.
• Lacking of tool support for verification.
• TA
• Well-developed tool support
• Lacking of high level composable graphical
  patterns to support systematic design for complex
  real-time systems

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Our Approach

• Define and map TCOZ constructs into composable TA
  graphical patterns
• For TA, a possible set of composable graphic
  patterns can be defined based on the semantics of
  TCOZ constructs.

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Our Approach

• Based on the TA patterns, a set of transformation
  rules are given for projecting TCOZ models into
  TA models
• For TCOZ, TAs tool support can be reused to
  check timing properties.

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TCOZ

• Integration of Object-Z with Timed CSP
• Features
• A Model of Time
• Communication InterfaceChannels, Sensors and
  actuators
• Active objects
• Network Topologies

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Timed Automata

• A timed automaton A is a tuple lt S, S0, S, C, E
  gt, where
• S is a finite set of states
• S0 is a set of initial states and a subset of S
• S is a set of labels
• C is a finite set of clocks, and
• E, a subset of SSS2CF(C), is the set of
  transitions. An edge lts, s, a, ?,dgt represents a
  transition from state s to state s on input
  symbol a. The set ?gives the clocks to be reset
  with this transition, and dis a clock constraint
  over C.

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A Gate Automaton
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Tools for Timed Automata

• Uppaal
• Developed by Uppsala University, Sweden and
  Aalborg University, Denmark
• Kronos
• Developed by Verimag,France
• Timed COSPAN
• Developed by Bell Labs,USA

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Definitions
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Sequential Composition Pattern
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Deadline Pattern
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WaitUntil Pattern
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Recursion Pattern
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Composing TA Patterns
Task A is repeated every t0 time units provided
that A is guaranteed to terminate before t0 time
units
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Rules for Translating Dynamic Information
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Rules for Translating Static Information

• In TCOZ, each object is translated as an
  automaton
• Each operation schema is translated as an atomic
  state
• Init operation schema is used to identify the
  initial state in the corresponding automaton

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Tool Support
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Case Study The Railway Crossing System
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Model Checking with UPPAAL
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Conclusion

• Provide a proficient interchange media for
  transforming TCOZ specification into TA models
• Provide a reusable high level library that may
  facilitate a systematical engineering process
  when using TA alone to design timed systems
• Build up the semantic link between TCOZ and TA
• Developed a translation tool from TCOZ to TA

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Future Work

• Encode the TA patterns to assist building TA
  models in a more systematical way.
• Integration of Timed Automata and Z language and
  relevant tool support.

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Thanks!