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12 Fallacies of Distributed Computing

1. The network is reliable (Bill Joy, Tom Lyon)
2. Latency isn't a problem (Bill Joy, Tom Lyon)
3. Bandwidth isn't a problem (Bill Joy, Tom Lyon)
4. The network is secure (Bill Joy, Tom Lyon)
5. The topology won't change (Peter Deutsch)
6. The administrator will know what to do (Peter Deutsch)
7. Transport cost isn't a problem (Peter Deutsch)
8. The network is homogeneous (James Gosling)

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class SomeClass
  def some_method
  end
end

C = Class.new(SomeClass)

m = C.instance_method(:some_method)

pp m.owner

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Some useful Postgres configuration changes for a dev machine:

log_connections = on
log_disconnections = on
log_statement = 'all'

Optionally, set log timestamps to local time

log_timezone = 'US/Central' # Or whatever your timezone is

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GEM
  remote: https://rubygems.org/
  specs:
    confstruct (1.0.2)
      hashie (~> 3.3)
    eventide-postgres (1.0.0.0)
      evt-consumer-postgres
      evt-entity_snapshot-postgres
      evt-entity_store
    evt-async_invocation (1.0.0.0)

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class Consumer
  include Consumer::Postgres

  handler SomeHandler
  handler SomeOtherHandler

  def error_raised(error, message_data)
    if error.instance_of?(MessageStore::ExpectedVersion::Error)
      self.(message_data)
    else

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handle Deposit do |deposit|
  account_id = deposit.account_id
  sequence = deposit.metadata.global_position

  # Retry once if an expected version error is raised by the write
  Retry.(MessageStore::ExpectedVersion::Error) do
    account, version = store.fetch(account_id, include: :version)

    # Idempotence protection using sequence numbers
    unless sequence > account.sequence 

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handle SomeMessage do |some_message|
  post_data = PostData.build(some_message)

  Retry.(HTTPError, millisecond_intervals: [100, 200]) do
    SomeHttpAPI.post(post_data)
  end
end

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class Consumer

  # ...

  def error_raised(error, message_data)
    # Do something with the error
    raise error
  end
end

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ComponentHost.start(component_name) do |host|
  
  # ...
  
  host.record_error(error) do
    SomeErrorReporter.(error)
  end
end

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module Events
  class Opened
    include Messaging::Message

    attribute :account_id, String
    attribute :customer_id, String
    attribute :time, String
  end

  class Deposited