Tendermint state replication test project

An Elixir application which uses tendermint for replicating the state in blockchain.

Goal

Simulation of passing a ball between defined participants as a blckochain transaction.

Assumptions:

• There is an array of whitelisted participants ["a", "b", "c", "d"].
• The initial state of the app is that participant "a" is holding a ball. This information is stored in the state under the key :participant_who_has_the_ball.
• checkTX block is responsible for validating transaction against a merkle proof and the current state of the blockchain.
• deliverTX is responsible for updating the state of the blockchain.
• tx tendermint parameter for passing the ball transaction is sent as a value of two fields tx="from=a:to=b" which is later parsed in the app.

Instalation

• Install tendermint (instructions)
• Install elixir (recommend asdf)
• Clone this repository

git clone git@github.com:Skoda091/tendermint-state-replication-test-project.git

Usage

• Run tendermint

  tendermint init

  tendermint node

• Run elixir app

  mix deps.get

  iex -S mix

• To pass the ball to a whitelisted participant, run from interactive Elixir (IEx):

  iex(1)> TendermintStateReplicationTestProject.BallService.pass_ball("a", "b")

  Where the first argument is the current owner of the ball and the second argument is the recipient. This fuction will create an HTTP request to tendermint.

  http://localhost:46657/broadcast_tx_commit?tx="from=a:to=b"

  Expected result of this function.

  %{
    "check_tx" => %{
      "code" => 0,
      "data" => "",
      "fee" => "0",
      "gas" => "0",
      "log" => ""
    },
    "deliver_tx" => %{"code" => 0, "data" => "", "log" => "", "tags" => []},
    "hash" => "492AC2718137712A2733177090971DB28B71F23E",
    "height" => 4
  }

  Example of incorrect transaction result.

    %{
    "check_tx" => %{
      "code" => 1,
      "data" => "",
      "fee" => "0",
      "gas" => "0",
      "log" => "Current ball owner is incorrect, a participant doesn't have the ball."
    },
    "deliver_tx" => %{"code" => 0, "data" => "", "log" => "", "tags" => []},
    "hash" => "492AC2718137712A2733177090971DB28B71F23E",
    "height" => 0
    }

• To check the current state of the ball run from iex:

  iex(2)> TendermintStateReplicationTestProject.BallService.check_ball_owner()

  Expected result of this function.

  %{
    "code" => 0,
    "decoded_key" => "participant_who_has_the_ball",
    "decoded_value" => "b",
    "height" => "0",
    "index" => "0",
    "key" => "7061727469636970616E745F77686F5F6861735F7468655F62616C6C",
    "log" => "",
    "proof" => "",
    "value" => "62"
  }

  Result extended with keys decoded_key and decoded_value only for the purpose of convinience while testing.

Tech stack

• elixir 1.6.0
• tendermint 0.14.0
• abci_server 0.3.0
• merkle_tree 1.2.1

Todo

• Add unit tests unit and integration
• Add integration tests
• Add documentation