Beambridge

Fork of Erlectricity by Scott Fleckenstein, Tom Preston-Werner (http://github.com/mojombo/erlectricity).

The original erlectricity gem doesn't seem to be supported and updated anymore, no commit in 4 years, a pull request pending for the last 3 years.

So I've forked the repository origin of the pending pull request and did cherry pick most of the pull request commits. And I had to rename the gem so I could publish it.

Development Status: port for 1.9.3, 2.0.x, 2.1.x in progress

Description

Beambridge allows a Ruby program to receive and respond to Erlang messages sent over the Erlang binary protocol.

Install

$ gem install beambridge

The Simplest Example

Ruby side (echo.rb)

require 'beambridge'

receive do |f|
  f.when([:echo, String]) do |text|
    f.send!([:result, "You said: #{text}"])
    f.receive_loop
  end
end

Erlang side (echo.erl)

-module(echo).
-export([test/0]).

test() ->
  Cmd = "ruby echo.rb",
  Port = open_port({spawn, Cmd}, [{packet, 4}, nouse_stdio, exit_status, binary]),
  Payload = term_to_binary({echo, <<"hello world!">>}),
  port_command(Port, Payload),
  receive
    {Port, {data, Data}} ->
      {result, Text} = binary_to_term(Data),
      io:format("~p~n", [Text])
  end.

Data Type Conversions and Matching

% Port is the port opened via open_port({spawn, Cmd}, [{packet, 4}, ...])
% Message is the Erlang term to encode and send to the port
send(Port, Message) ->
  port_command(Port, term_to_binary(Message)).

# Each triplet below represents:
# (line 1) the Erlang call
# (line 2) the Ruby matcher
# (line 3) the Ruby output

send(Port, test).
f.when(:test) { p :ok }
# :ok

send(Port, {atom, symbol}).
f.when([:atom, Symbol]) { |sym| p sym }
# :symbol

send(Port, {number, 1}).
f.when([:number, Fixnum]) { |num| p num }
# 1

send(Port, {string, <<"foo">>}).
f.when([:string, String]) { |str| p str }
# "foo"

send(Port, {array, [1,2,3]}).
f.when([:array, Array]) { |arr| p arr }
# [1, 2, 3]

send(Port, {array, [<<"abc">>, <<"def">>]}).
f.when([:array, Array]) { |arr| p arr }
# ["abc", "def"]

send(Port, {hash, [{key,val}]}).
f.when([:hash, Erl.hash]) { |hash| p hash }
# {:key=>:val}

send(Port, {object, {1,{2},3,<<"four">>}}).
f.when([:object, Any]) { |any| p any }
# [1, [2], 3, "four"]

Contribute

If you'd like to hack on Beambridge, start by forking my repo on GitHub:

https://github.com/mathieul/beambridge

To get all of the dependencies, install the gem first. The best way to get your changes merged back into core is as follows:

Clone down your fork
Create a topic branch to contain your change
Hack away
Add tests and make sure everything still passes by running rake
If you are adding new functionality, document it in the README.md
Do not change the version number, I will do that on my end
If necessary, rebase your commits into logical chunks, without errors
Push the branch up to GitHub
Send me (mojombo) a pull request for your branch