This releases adds GenStage event producers, a composable abstraction for consuming data from third-party systems and a behaviour for exchanging events with back-pressure between Elixir processes. GenStage integration makes Steemex usage simpler and easier: just start a GenStage Consumer with a following option: subscribe_to: Steemex.Stage.Blocks.Producer or subscribe_to: Steemex.Stage.Ops.ProducerConsumer. Both producers use BroadcastDispatcher -- every blockchain event will be broadcasted to all subscribed consumers.

GenStage is a great tool for blockchain related tasks and I'm nearly certain that GenStage is here to stay for a long time.

Repos and docs

• github
• hex.pm
• docs

Changelog

• breaking: previous Steemex.Streamer module was removed
• stream_to config option was removed
• new Steemex.Stage.Blocks.Producer module
• new Steemex.Stage.Ops.ProducerConsumer module
• new supervisor module for GenStage producers
• basic example of GenStage consumer for steem operation events
• updated readme

A GenStage consumer example

defmodule Steemex.Stage.Ops.ExampleConsumer do
  use GenStage
  require Logger

  def start_link(args, options \\ []) do
    GenStage.start_link(__MODULE__, args, options)
  end

  def init(state) do
    {:consumer, state, subscribe_to: state.subscribe_to}
  end

  def handle_events(events, _from, state) do
    for op <- events do
      Logger.info """
      New operation:
      #{inspect op}
      """
    end
    {:noreply, [], state}
  end

end

Roadmap

• Investigate using GenStage
• Add more utility functions
• Add more types and structs
• Add transaction broadcast

About Elixir

Elixir is a functional programming language with superior concurrency primitives, distributed computation and fault tolerance capabilities based on Erlang/OTP.
Personally, I am really happy with my bet on Elixir to build cryptotokens related apps and strongly recommend every developer to try it.

Learning resources:

• ElixirConf Jose Valim Keynote
• ElixirConf 2016 Chris McCord Keynote
• Elixir School
• Elixir Crash Course

(∩^o^)⊃━☆゜.*