Implementing Bully algorithm in Telelogic Tau

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Implementing Bully algorithm in Telelogic Tau

• Presented By
• Sadek Hamdan

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Outline

• Introduction to SDL
• Telelogic Tau
• Bully algorithm
• Project progress
• To be done
• Conclusion

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Introduction to SDL

• Specification and Description Language is a cross
  platform language targeted at the unambiguous
  specification and description of the behaviour of
  reactive and distributed systems.
• Defined by the International Telecommunication
  Union (ITU-T) as recommendation Z.100.
• The first version was issued in 1976, the latest
  in 1996
• The behaviour is modeled using states, input and
  output messages and decisions

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Introduction to SDL - Example
(c) Multimedia Communications Research Laboratory
(MCRLab) http//www.mcrlab.uottawa.ca
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Introduction to SDL - Example
(c) Multimedia Communications Research Laboratory
(MCRLab) http//www.mcrlab.uottawa.ca
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Telelogic Tau

• Is a UML modeling tool that supports automated
  code generation and model verification.
• Enables users to quickly visually develop large,
  complex information systems using Model Driven
  Development (MDD)
• On April 28, 2008, IBM completed its purchase of
  Telelogic

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Telelogic Tau

• We are interested in Telelogic Tau because it
• Simulates our designs and tests for errors as we
  develop
• Implements a requirements-driven approach
• Automates our document generation
• Designs, develops, and delivers high-quality
  software
• Automatically generates, executes, and manages
  test cases
• Extends and customizes our modeling environment

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Bully algorithm

• A method in distributed computing for dynamically
  selecting a leader.
• Used in networks of complete topology.
• Bully means the process with the highest ID
  number is the leader.
• A process run it when
• It joins the network OR
• When it detects that the current leader is down

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Bully algorithm - Steps

• Process i send Election message (I want to be the
  leader) to processes with larger ID.
• Wait for Reply message
• If a reply is received go to step 3
• If NO reply is received after time T1, then i
  elects itself the leader, and broadcast a leader
  message.
• Wait for Leader message
• If leader message is received, store the leader
  ID
• If NO message is received after time T2, then
  re-initiate election by sending election message

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Bully algorithm local variables

• failed Boolean variable true if the leader is
  failed.
• leader the ID of the leader.
• myID the ID of the process
• Array of processes IDs

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Project progress

• Getting familiar with the Telelogic Tau.
• Walkthrough of Telelogic Tau tutorial on how to
  design and test a coffee machine.
• Written specification of Bully algorithm
• Started implementation of the behaviour of a
  node.
• Started implementation of a Main process that
  initializes the other processes and requests any
  node to start the election

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Project progress Node SDL
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Project progress Node SDL
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Project progress Main SDL
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To be done

• Improve the SDL diagrams for Node and Main
• Create test cases and observing MSC charts to
  verify the model

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Conclusion

• This project was beneficial to
• become familiar with SDL and Telelogic Tau
• Improve the ability to design and test the
  specification of distributed system

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References

• Teleogic Tau web site http//www.telelogic.com/pr
  oducts/tau/tau/overview.cfm
• http//en.wikipedia.org/wiki/Telelogic
• http//en.wikipedia.org/wiki/Specification_and_Des
  cription_Language
• Course website
• http//www.site.uottawa.ca/bochmann/ELG7187C-2009
  W/CourseNotes/Literature/Overview20of20SDL.pdf

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Dankie
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