Communicating Transaction Processes

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Communicating Transaction Processes

• P.S. Thiagarajan
• National University of Singapore
• Joint Work with
• Abhik Roychoudhury

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The Main Features

• To support System Level Design
• One Level of Abstraction higher than C, C, VHDL
  ..
• UML-compatible
• MSCS Asynchronous control flow
• Based on MSCs (Message Sequence Charts)
• Sequence Diagrams

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Why System Level Design?

• Closer to end-use(r) .
• Less detailed and more architecture-neutral.
• Easier reuse/adaptaton.
• Easier to verify.
• Safety-critical applications need to be correct.
• Catch design errors early.
• Coupling with a correct-by-construction synthesis
  method is an attractive option.

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What is Available?

• Data flow graphs.
• Automata of various kinds.
• Petri nets.
• State charts.
• Esterel, Lustre.
• SDL, UML.

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Why UML-compatible?

• UML is getting rapidly established as a standard.
• Mainly in software engineering projects
• Increasingly so in embedded systems domain.
• Offers a suite of graphical notations
• Multiple views
• Behavioral and structural diagrams.
• Object orientation.
• Reuse, adaptation

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An Idealized Design Flow
Requirements
High Level Description
Exec. Specifications.
Intermediate representation
SW/HW Implementation.
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Requirements and Exec. Specifications

• Requirements Message Sequence Charts (MSCs)
• Exec. Specifications
• State charts.
• UML supports both but no clear distinction made.
• Other Exec. Spec.
• Petri nets,
• MPAs (Message Passing Automata), .

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MSCs

• Message Sequence Charts
• Describe scenarios.
• A finite pattern of interaction between agents
  (object instances,..).
• A story

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Message Sequence Charts
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Message Sequence Charts
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Message Sequence Charts
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Message Sequence Charts
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Message Sequence Charts
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Message Sequence Charts
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Message Sequence Charts
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Message Sequence Charts
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Message Sequence Charts
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Message Sequence Charts
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Message Sequence Charts
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Message Sequence Charts
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Message Sequence Charts
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CTPs

• Communicating Transaction Processes.
• An executable spec. mechanism.
• Based on MSCs.
• A network of interacting agents.
• Agents interaction pattern behavior
• Standard distributed system model
• Interaction
• Guarded choice of MSCs.
• Transaction schemes.

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Distributed System Models

• Petri nets
• Data flow graphs
• Statecharts
• Distributed transition systems (many kinds!)
• Process algebras (CCS, CSP, )

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But the boxes will have internal structure. A
complex Transaction Scheme.
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Transaction Scheme
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P11 Transaction Scheme
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Analysis Issues

• Determine whether a CTP is bounded.
• Determine if a CTP can deadlock.
• Determine if a CTP is well-formed.

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Current Status
Case Studies
Modeling
The CTP Model
Verification
Analysis
SMV
ES Representation
Simulation Synthesis
Verilog
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Current Status
Pankaj Jain Nikhil Jain Kamrul Hasan
Talukdar Tran Tuan Anh Ge Zhiguo
Case Studies
Modeling
The CTP Model
Verification
Analysis
SMV
ES Representation
Simulation Synthesis
Verilog
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Future Work

• Add multiple instances of a process.
• Object features
• Add timing constraints.
• Develop the computational model.
• Interactions with environment (sense, actuate)
• Computational steps (control law)
• Schedulability is a key issue.
• HW/SW Partitioning Architectural mapping
  Synthesis?