distributed_system_coursework/presentation/presentation.md

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A Paxos Implementation

Andre Henriques, Seoeun Lee

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Basis of the implentation

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Steps

receive do
  {:leader_elector, proc} -> ...
  {:propose, inst, value, t, pid_to_inform} -> ...
  {:prepare, proc, inst, ballot} -> ...
  {:nack, inst, ballot} -> ...
  {:prepared, inst, ballot, accepted_ballot, accepted_value} -> ...
  {:accept, inst, ballot, value} -> ...
  {:accepted, inst, ballot} -> ...
  {:decide, inst, value} -> ...
end

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Step 1 - "Requirements"

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Step 1 - "Requirements" non-trivial aspects

receive do
  {:propose, inst, value, t, pid_to_inform} ->
    ...
    broadcast({:other_propose, inst, value})
    ...
  {:other_propose, inst, value} -> ...
end

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Step 2 - "Prepare"

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Step 2 - "Prepare" non-trivial aspects

receive do
  {:nack, inst, ballot, new_ballot} ->
    ...
    broadcast({:abort, inst, ballot})
    ...
  {:abort, inst, ballot} -> ...
end

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Step 3 - "Accept"

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Step 3 - "Accept" non-trivial aspects

receive do
  {:accepted, inst, ballot} ->
    ...
    broadcast({:decide, inst, value})
    ...
  {:decide, inst, value} -> ...
end

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Step 4 - "Leader Crash"

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Application

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Atomas

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Safety

• If a game state exists, then it was created by a user
• The game state can not divert.

Liveness

• Eventually all users will have the same game state

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Questions?