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blockchain_with_transactions.rb
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blockchain_with_transactions.rb
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###########################
# build your own blockchain from scratch in 20 lines of ruby!
#
# to run use:
# $ ruby ./blockchain_with_transactions.rb
#
# transactions (hyper) ledger / book:
#
# from: Dutchgrown to: Vincent what: Tulip Bloemendaal Sunset qty: 10
# from: Keukenhof to: Anne what: Tulip Semper Augustus qty: 7
#
# from: Flowers to: Ruben what: Tulip Admiral van Eijck qty: 5
# from: Vicent to: Anne what: Tulip Bloemendaal Sunset qty: 3
# from: Anne to: Julia what: Tulip Semper Augustus qty: 1
# from: Julia to: Luuk what: Tulip Semper Augustus qty: 1
#
# from: Bloom & Blossom to: Daisy what: Tulip Admiral of Admirals qty: 8
# from: Vincent to: Max what: Tulip Bloemendaal Sunset qty: 2
# from: Anne to: Martijn what: Tulip Semper Augustus qty: 2
# from: Ruben to: Julia what: Tulip Admiral van Eijck qty: 2
#
# from: Teleflora to: Max what: Tulip Red Impression qty: 11
# from: Anne to: Naomi what: Tulip Bloemendaal Sunset qty: 1
# from: Daisy to: Vincent what: Tulip Admiral of Admirals qty: 3
# from: Julia to: Mina what: Tulip Admiral van Eijck qty: 1
#
# from: Max to: Isabel what: Tulip Red Impression qty: 2
#
# (source: tulips on the blockchain - public distributed (hyper) ledger
# @ github.com/openblockchains/tulips )
require "digest" # for hash checksum digest function SHA256
require "pp" # for pp => pretty printer
class Block
attr_reader :index
attr_reader :timestamp
attr_reader :transactions
attr_reader :transactions_count
attr_reader :previous_hash
attr_reader :hash
def initialize(index, transactions, previous_hash)
@index = index
@timestamp = Time.now.utc
@transactions = transactions
@transactions_count = transactions.size
@previous_hash = previous_hash
@hash = calc_hash
end
def calc_hash
sha = Digest::SHA256.new
sha.update( @index.to_s +
@timestamp.to_s +
@transactions_count.to_s +
@transactions.to_s +
@previous_hash )
sha.hexdigest
end
## ruby note: the splat operator (that is, *) turns list of passed in transactions into array
def self.first( *transactions ) # create genesis (big bang! first) block
## uses index zero (0) and arbitrary previous_hash ("0")
Block.new( 0, transactions, "0" )
end
def self.next( previous, *transactions )
Block.new( previous.index+1, transactions, previous.hash )
end
end # class Block
#####
## let's get started
## build a blockchain a block at a time
b0 = Block.first(
{ from: "Dutchgrown", to: "Vincent", what: "Tulip Bloemendaal Sunset", qty: 10 },
{ from: "Keukenhof", to: "Anne", what: "Tulip Semper Augustus", qty: 7 } )
b1 = Block.next( b0,
{ from: "Flowers", to: "Ruben", what: "Tulip Admiral van Eijck", qty: 5 },
{ from: "Vicent", to: "Anne", what: "Tulip Bloemendaal Sunset", qty: 3 },
{ from: "Anne", to: "Julia", what: "Tulip Semper Augustus", qty: 1 },
{ from: "Julia", to: "Luuk", what: "Tulip Semper Augustus", qty: 1 } )
b2 = Block.next( b1,
{ from: "Bloom & Blossom", to: "Daisy", what: "Tulip Admiral of Admirals", qty: 8 },
{ from: "Vincent", to: "Max", what: "Tulip Bloemendaal Sunset", qty: 2 },
{ from: "Anne", to: "Martijn", what: "Tulip Semper Augustus", qty: 2 },
{ from: "Ruben", to: "Julia", what: "Tulip Admiral van Eijck", qty: 2 } )
b3 = Block.next( b2,
{ from: "Teleflora", to: "Max", what: "Tulip Red Impression", qty: 11 },
{ from: "Anne", to: "Naomi", what: "Tulip Bloemendaal Sunset", qty: 1 },
{ from: "Daisy", to: "Vincent", what: "Tulip Admiral of Admirals", qty: 3 },
{ from: "Julia", to: "Mina", what: "Tulip Admiral van Eijck", qty: 1 } )
blockchain = [b0, b1, b2, b3]
pp blockchain
######
# will pretty print (pp) something like:
#
# [#<Block:0x2da3da0
# @hash="32bd169baebba0b70491b748329ab631c85175be15e1672f924ca174f628cb66",
# @index=0,
# @previous_hash="0",
# @timestamp=2017-09-24 11:40:15 UTC,
# @transactions=
# [{:from=>"Dutchgrown", :to=>"Vincent", :what=>"Tulip Bloemendaal Sunset", :qty=>10},
# {:from=>"Keukenhof", :to=>"Anne", :what=>"Tulip Semper Augustus", :qty=>7}],
# @transactions_count=2>,
# #<Block:0x2da2ff0
# @hash="57b519a8903e45348ac8a739c788815e2bd90423663957f87e276307f77f1028",
# @index=1,
# @previous_hash=
# "32bd169baebba0b70491b748329ab631c85175be15e1672f924ca174f628cb66",
# @timestamp=2017-09-24 11:40:15 UTC,
# @transactions=
# [{:from=>"Flowers", :to=>"Ruben", :what=>"Tulip Admiral van Eijck", :qty=>5},
# {:from=>"Vicent", :to=>"Anne", :what=>"Tulip Bloemendaal Sunset", :qty=>3},
# {:from=>"Anne", :to=>"Julia", :what=>"Tulip Semper Augustus", :qty=>1},
# {:from=>"Julia", :to=>"Luuk", :what=>"Tulip Semper Augustus", :qty=>1}],
# @transactions_count=4>,
# #<Block:0x2da2720
# @hash="ec7dd5ea86ab966d4d4db182abb7aa93c7e5f63857476e6301e7e38cebf36568",
# @index=2,
# @previous_hash=
# "57b519a8903e45348ac8a739c788815e2bd90423663957f87e276307f77f1028",
# @timestamp=2017-09-24 11:40:15 UTC,
# @transactions=
# [{:from=>"Bloom & Blossom", :to=>"Daisy", :what=>"Tulip Admiral of Admirals", :qty=>8},
# {:from=>"Vincent", :to=>"Max", :what=>"Tulip Bloemendaal Sunset", :qty=>2},
# {:from=>"Anne", :to=>"Martijn", :what=>"Tulip Semper Augustus", :qty=>2},
# {:from=>"Ruben", :to=>"Julia", :what=>"Tulip Admiral van Eijck", :qty=>2}],
# @transactions_count=4>,
# #<Block:0x2da1ee0
# @hash="a1c5e5035403214a7349c2dedb7858ed411a351d7cb23d196583687a9a019785",
# @index=3,
# @previous_hash=
# "ec7dd5ea86ab966d4d4db182abb7aa93c7e5f63857476e6301e7e38cebf36568",
# @timestamp=2017-09-24 11:40:15 UTC,
# @transactions=
# [{:from=>"Teleflora", :to=>"Max", :what=>"Tulip Red Impression", :qty=>11},
# {:from=>"Anne", :to=>"Naomi", :what=>"Tulip Bloemendaal Sunset", :qty=>1},
# {:from=>"Daisy", :to=>"Vincent", :what=>"Tulip Admiral of Admirals", :qty=>3},
# {:from=>"Julia", :to=>"Mina", :what=>"Tulip Admiral van Eijck", :qty=>1}],
# @transactions_count=4>]